How to Rebuild the Rear Axle

In recent years, rear axles have become so robust and reliable that most mechanics have long forgotten how to diagnose and repair them, much less modify them. The rear axle is one part of the vehicle that has evolved over time into a variety of designs but has never been replaced. We can’t say that about many other technologies in the vehicle. While ignition points, carburetors, and lever shocks have faded into obscurity as more precise and efficient devices gradually superceded them, today’s rear axle designs are not much different than they were 30 years ago.

 


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Yes, we have made huge advances in materials to increase strength, developed better mounting structures to control deflection and noise, and designed even better bearings and seals to ensure long-term durability. We have even developed suites of sophisticated tools to analyze and predict the math and physics behind gear reaction loads. But the same basic function and implementation is evident.

The most frequent complaint made of any rear axle is a gear-generated or bearing-generated noise. The next most common complaint is a fluid leak. Fortunately, actual gear failures are very uncommon on modern vehicles, so gears are typically serviced only when the vehicle owner desires a ratio change. Altering the axle ratio or swapping a limited-slip differential in place of an open differential can greatly change the performance and feel of the vehicle.

For instance, a 500-hp big-block with a 2.73:1 ratio axle will not launch anywhere near as hard as the same car with a set of 4.10 gears. However, you need to resist the temptation to install 4.10 gears simply because it’s a larger numerical ratio. First you must understand the effect of tire size on the overall ratio. And you must understand the basic structure and maintenance of axles.

The typical beam axle has to provide the structure to support the gears and differential. It also needs to provide mounting points for the brake hardware and suspension, and must react to loads imparted by every interfacing vehicle system. This chapter covers most of the in-depth processes required to rebuild the complete rear-axle assembly. I will also include references to specific topics that are covered in other chapters, namely hypoid gear set contact pattern (Chapter 6) and limited-slip differential rebuild (Chapter 4).

 

Common Axle Problems

To best diagnose an axle problem, it is always preferable to road test the vehicle before tearing it apart unless, of course, the part failed catastrophically and made its own exit through the axle housing. Most issues can be lumped into one of the following categories: noise, vibration, or leakage. Try to isolate the exact circumstances that exhibit the noise. Is it occurring during mild acceleration, heavy acceleration, during deceleration, or all the time? Does it get worse as you drive faster or slower? Listening is an important step as it can help guide your pursuit to answer the question, “What broke?”

Noise

Typically, noises that get worse as speed increases are related to bearings or to the wheel/tire assembly. Tire noise is usually most prominent around 60 to 80 mph. Noises that change with acceleration and deceleration are typically gear noises. (Vibrations usually point to the universal joints or to driveshaft balance issues.) Clunk noises or thumping noises in the vehicle occurring during direction changes (when shifting from drive to reverse, or when applying and releasing the throttle, or when cornering) are typically from excessive backlash in the hypoid gears, differential gears, or excessive wear in these components or bearings. Severely worn universal joints in the driveshaft can cause similar disturbances, which are often accompanied by clicking noises.

Clunks or noises that get louder during turns usually suggest that something is wrong with the differential gears or case. Believe it or not, even brand-new axles as well as improperly set up “rebuilt” axles will make noise that only gets worse with time. Interestingly, the blame for such issues is often shifted toward the gear manufacturer especially on Internet forums when the true cause can usually be traced to a flawed gear setup.

Whining noises or high-pitched sounds that vary with a vehicle traveling at speed in a straight line typically emanate from worn hypoid gears and bearings. Worn bearings usually have a lower pitched sound while worn or misadjusted gears generate a higher pitched sound. If you hear a whine during acceleration that gets noticeably quieter on deceleration, a worn pinion head bearing could be the cause. If the noise is present during deceleration and not acceleration, the pinion tail bearing could be the cause.

Wheel-end bearings are unique for semi-float axles (see Chapter 2) because the inner bearing race is the axle itself. Over time, this surface can wear considerably, and when it has significantly worn, this type of bearing or surface problem produces a rumbling or roaring noise while the vehicle is in motion. You may also notice that the tone changes as you turn back and forth.

Vibration

Vibration can be one of the trickier issues to diagnose. You want to first rule out a driveshaft problem (see Chapter 8); or it could even be something as simple as a wheel out of balance. You may remember that really cool, sideways burnout you did coming around the corner you remember, the one that ended with a hard slide into the curb. Well, in this situation, you may have bent your axle. This is far more common than you might think. One easy way to check if the axle flange is bent is to measure runout with a dial indicator.

 

Mounting a dial indicator on the axle housing and placing the indicator on the flange is the easiest method for measuring axle flange runout. As you rotate the axle shaft, make certain that shaft does not plunge in or out. I like to push the shaft inboard and then take the measurements. Typical values should not exceed 0.030 inch.

Mounting a dial indicator on the axle housing and placing the indicator on the flange is the easiest method for measuring axle flange runout. As you rotate the axle shaft, make certain that shaft does not plunge in or out. I like to push the shaft inboard and then take the measurements. Typical values should not exceed 0.030 inch.

 

If the axle shaft is bent, it is harder to detect. One indication is that the shaft is difficult to remove. You can also support the axle with V-blocks and measure shaft runout. Do not try to straighten axles that have been bent, as they were overloaded in the first case, and now you are just going to overload them more trying to get them straight. This continued overloading weakens the shaft. This is similar to bending a paperclip back and forth a few times; it ends up breaking in half. They need to be replaced.

Remember that time spent diagnosing a problem is time well spent. The reason to isolate the source of the noise allows you to eliminate the culprit for good. Even if you have already decided to replace all of the bearings and seals (which is highly recommended), you need to look for other problems that may have caused the bearings or seals to go bad in the first place, such as a bent axle or a worn seal surface.

Leakage

Leaks are easy to spot; just look very closely for any signs of fluid leakage. The easiest leak to repair is the rear-axle housing cover. Any of the radial lip seals that are on the pinion flange or wheel ends require the axle to be partially disassembled. Usually dirt and debris sticks to the leaking fluid, making it relatively easy to spot the source of the leak. As always, exercise common sense. I have worked on some vehicles where the engine has leaked so much oil that the entire floorpan is soaked with 30-weight engine oil. Most of the time, the source of the leak is obvious. Other times it may not be as obvious, such as when oil is pumped out of the axle vent. Unintentional overfilling of the axle, or ingesting water during operation, can overfill the axle and cause it to leak.

 

Radial lip-style seals are very common throughout the entire drivetrain to seal rotating shafts. This type of seal is used at the axle wheel ends and pinion shaft.

Radial lip-style seals are very common throughout the entire drivetrain to seal rotating shafts. This type of seal is used at the axle wheel ends and pinion shaft.

 

Vehicle Preparation

As discussed previously, the only minor repair is an axle cover leak. Just about any other repair requires removal of the axle shafts for access to the item(s) that need to be repaired or replaced. Before getting into the removal of these components, I need to address some basic items. First off, you need to have the vehicle supported on a flat surface with enough room around the sides of the car to allow the axle shafts to be completely removed.

Each axle shaft is typically about 3 feet long and needs to be removed to access the wheel-end bearings and seals. You would hate to have the vehicle parked close to one side of the garage and have the axle shaft hit the garage wall before it completely clears the axle housing. It’s similar to removing a camshaft with the motor still installed in the vehicle; you need to clear the radiator and air conditioning condenser. So give yourself plenty of room, ample time, and patience. Place a jack on the center section of the axle and raise the rear wheels off the ground. Be careful, as each axle housing is unique and you want to avoid damaging the stamped steel cover if so equipped.

 

It is important to make certain that you have adequate clearance around the vehicle when you begin to disassemble rear axles. I like to place the car in the middle of the garage for maximum work space on both sides.

It is important to make certain that you have adequate clearance around the vehicle when you begin to disassemble rear axles. I like to place the car in the middle of the garage for maximum work space on both sides.

 

The cast center is a good place to lift the entire rear axle and vehicle. Just make certain that the jack is on the casting and not pressing on the stamped-steel cover; otherwise, you could damage or puncture it. And if the covers are made out of composites, they will crack. This Ford axle actually has clearance between the cover bottom and the axle housing, so there is little danger of damaging the cover.

The cast center is a good place to lift the entire rear axle and vehicle. Just make certain that the jack is on the casting and not pressing on the stamped-steel cover; otherwise, you could damage or puncture it. And if the covers are made out of composites, they will crack. This Ford axle actually has clearance between the cover bottom and the axle housing, so there is little danger of damaging the cover.

 

If you do enough axle work, a fabricated axle stand that supports the axle by the tubes is very helpful. This basic stand raises the axle far enough off the floor, so you don’t have bend over the housing to work on it. You may also want to add casters with locks, so you can easily roll the axle around the shop.

If you do enough axle work, a fabricated axle stand that supports the axle by the tubes is very helpful. This basic stand raises the axle far enough off the floor, so you don’t have bend over the housing to work on it. You may also want to add casters with locks, so you can easily roll the axle around the shop.

 

If you are only working on axles once in awhile, you can use jack stands. This is a little trickier and care should be taken because it is easy to knock them over. Nonetheless, this is an excellent way to support an axle that has been removed from the vehicle and is easy on the budget.

If you are only working on axles once in awhile, you can use jack stands. This is a little trickier and care should be taken because it is easy to knock them over. Nonetheless, this is an excellent way to support an axle that has been removed from the vehicle and is easy on the budget.

 

Alternatively, you can simply raise the vehicle from the frame rails and support the vehicle with jack stands. I like to get the vehicle as high as possible and use jack stands to support the frame rails. Then the axle will hang as low as possible. Just one quick comment about complete axle assembly removal: If you are going to remove the entire axle assembly to work on it separately, leave the wheels in place so that you can roll the axle around the garage. Otherwise, you will fight to balance it on a floor jack. Completely removing the entire axle and servicing it on a stand preserves much sanity.

Or you can use a few jack stands to help hold it in place. If you have access to a vehicle hoist, then the above doesn’t apply to your situation and you should consider yourself fortunate that you don’t have to crawl around on the ground and work on your back. If you are just going to be repairing items and not completely stripping, sand blasting, and repainting the axle housing, it is best to avoid the hassle of removing brake lines and parking brake cables and suspension to remove the axle. The hoist allows you to comfortably work under the car, so take advantage of that.

 

Axle Disassembly

With the vehicle safely supported, you can get underneath. Carefully examine the axle, propshaft, brake lines, and even the suspension mounting points. I have worked on some vehicles that have a horrible clunk noise, only to find that the suspension bushings are excessively worn or the sub-frame mounting brackets have ripped out of the sub-frame. Never look past the obvious culprits. I am not going to cover every axle here, but rather the foundations of a complete “typical” axle disassembly.

I have chosen the Ford Mustang 8.8- inch axle, which is similar to the Chrysler and GM axles. The first step is to drain the axle fluid. Some axles actually have drain plugs, but these are few and far between; you might get lucky, so be sure to check the bottom for a drain plug. Most V-8-powered vehicles do not have drain plugs.

Without the advantage of a drain plug, you need to remove the rear cover in order to drain the fluid; this is similar to removing the transmission pan. As will be discussed more later (in Chapter 6), gear oil is extremely smelly and nearly impossible to get off your clothes and skin. Make sure that you have planned for that; some folks like to wear latex gloves for this part of the work. First, remove every other bolt, and then remove all of the bottom bolts. Next loosen and back out the remaining few top bolts but do not remove them completely, to prevent the cover from falling into the drain pan. The covers are usually held in place and sealed with a paper gasket or a bead of Room Temperature Vulcanizing (RTV) sealant. Slip a standard flat-blade screwdriver between the cover and the axle and lightly pry the cover away. Be careful not to score or damage the mating surface of the housing and the cover because this would prevent these two parts from sealing properly.

 

Once all of the cover bolts have been removed, a little persuasion with a screwdriver and hammer is often required to separate the cover from the housing. Just a light tap with the hammer usually does the trick. (Randall Shafer)

Once all of the cover bolts have been removed, a little persuasion with a screwdriver and hammer is often required to separate the cover from the housing. Just a light tap with the hammer usually does the trick. (Randall Shafer)

 

Once the cover is removed, you get your first glimpse on the internals of the axle. The ring gear is on the left, and the differential is bolted in place. This is a Ford-style traction lock differential (see Chapter 4). (Randall Shafer)

Once the cover is removed, you get your first glimpse on the internals of the axle. The ring gear is on the left, and the differential is bolted in place. This is a Ford-style traction lock differential (see Chapter 4). (Randall Shafer)

 

A single bolt holds the differential pin in place. If you do not see it on your application, rotate the differential 180 degrees because chances are it is on the opposite side. Once the differential retention bolt is removed the pin can be pushed out. (Randall Shafer)

A single bolt holds the differential pin in place. If you do not see it on your application, rotate the differential 180 degrees because chances are it is on the opposite side. Once the differential retention bolt is removed the pin can be pushed out. (Randall Shafer)

 

For most applications, the differential pin slides out. In some instances, especially a heavily worn differential, grooves may be worn into the pin, which makes the pin much more difficult to remove. This particular pin shows the usual wear marks (the two ovals in the middle of the shaft) from the axle shaft hitting it. (Randall Shafer)

For most applications, the differential pin slides out. In some instances, especially a heavily worn differential, grooves may be worn into the pin, which makes the pin much more difficult to remove. This particular pin shows the usual wear marks (the two ovals in the middle of the shaft) from the axle shaft hitting it. (Randall Shafer)

 

The fluid will begin pouring out of the gap that you have created. Have a drain pan in place to catch the fluid. Now you can remove the remaining bolts and the cover can be completely removed. At this point, you should see the ring gear and the internals of the axle itself.

The next step is to rotate the differential and ring gear assembly in order to gain access to the differential pin retaining bolt.

Loosen and remove the bolt in order to allow the differential pin to come out. On most axles the differential pin can be lightly pushed out. With some axles subjected to hard use, and as a result the differential pinion gears have worn into the pin, removal is difficult, but the differential pin nevertheless needs to come out for servicing. Worst case scenario is to get in there with a torch and cut it out. This is extremely difficult, so take your time and try to force stubborn pins out. You may need to get creative. Usually if you tap the opposite end of the pin where the bolt went in you can drive the pin out slightly and then rotate the differential 180 degrees and insert the bolt in the pin hole to try to pry it out of the case.

With the differential pin out of the way, the axle shafts can now be pushed inboard to give access to the C-washer that holds them in place. First, you need to remove the wheels.

Then the brake hardware needs to be removed. This can be as simple as removing the drums or as involved as removing the brake calipers, caliper brackets, and rotors.

At times, especially on off-road vehicles that have had the wheel ends submerged in water and mud, the brake drums are corroded in place. There are a few methods to coerce the drums off. You can drive them farther on with a hammer by striking them on the flat part between the stud holes. A trick that works quite well is to place one hammer on the flat surface of the drum between the studs and hit it with another hammer. You can use a puller to yank them off or you may have to resort to heating them with a torch to get them off. I have seen some drums and rotors that actually end up cracking before they come off. In those extreme cases, the drum or rotor needs to be replaced.

 

Before working on the axle itself, first remove the wheels. Use an impact gun to remove the lug nuts. (Randall Shafer)

Before working on the axle itself, first remove the wheels. Use an impact gun to remove the lug nuts. (Randall Shafer)

 

Most muscle cars have factory drum brakes. While many of the newer vehicles, such as this Mustang rear axle, come equipped from the factory with rear disc brakes. There are, of course, aftermarket disc brakes available for most common applications.

Most muscle cars have factory drum brakes. While many of the newer vehicles, such as this Mustang rear axle, come equipped from the factory with rear disc brakes. There are, of course, aftermarket disc brakes available for most common applications.

 

Some brake drums or rotors that have not been removed for decades or are corroded, rusted, and almost always difficult to remove. As a last resort, you may need to bring out the “gas ax” and apply some heat. (Randall Shafer)

Some brake drums or rotors that have not been removed for decades or are corroded, rusted, and almost always difficult to remove. As a last resort, you may need to bring out the “gas ax” and apply some heat. (Randall Shafer)

 

This tone wheel provides a speed signal back to the anti-lock brake system that measures speed of the wheel. Be careful so you don't damage this sensor. However, if you do, they are relatively inexpensive and most chain parts stores have them in stock.

This tone wheel provides a speed signal back to the anti-lock brake system that measures speed of the wheel. Be careful so you don’t damage this sensor. However, if you do, they are relatively inexpensive and most chain parts stores have them in stock.

 

This particular sensor requires an inverted torx socket in order to remove it from the axle. If you don’t have this tool, you may have difficulty removing the sensor. You really want to avoid using vise grips.

This particular sensor requires an inverted torx socket in order to remove it from the axle. If you don’t have this tool, you may have difficulty removing the sensor. You really want to avoid using vise grips.

 

If your last resort was to apply heat to the drum or rotor, you may end up with some damage. Typically, the seals are ruined, but they should be replaced anyway so this isn't a concern. In this situation, we actually ended up melting the speed sensor.(Randall Shafer)

If your last resort was to apply heat to the drum or rotor, you may end up with some damage. Typically, the seals are ruined, but they should be replaced anyway so this isn’t a concern. In this situation, we actually ended up melting the speed sensor.(Randall Shafer)

 

Depending on what year Ford 8.8-inch you are working on, you may have to deal with the ABS tone wheel sensors first. This style first went into production on the Mustang SN95 chassis.

The sensor needs to be moved slightly inboard so that the axle can travel inboard the correct amount to expose the C-washer. Remove the sensor retaining bolt from the back side of the sensor, and then push the sensor inboard about 1/4 inch. The plastic sensor is very delicate and easy to damage. Since the sensor may be corroded in place, be very careful because it may be difficult to move. If you break it, just replace it with a new one. In the case where a torch was required, we ended up melting the sensor.

Now the axle should freely slide inboard. It will go in about 1/2 inch or so. This is enough to expose the C-washer from its retention pocket in the side gear. In some cases, the washer simply falls out. In others, it may be held in place with an O-ring or just stuck from the lube film. The clip is tricky to remove if you are working on a limited-slip differential, so it’s helpful to use a magnetic pick-up tool to reach in and grab the washer.

Repeat this process for the other side. Then the axle shafts can be removed from the axle housing. It is best to support the shaft at the wheel end because this helps protect the bearing and seal from damage. You need to keep in mind that the seal has likely been damaged from the years of brake dust and rust, accumulated on the axle shaft, that was forced into the seal surface to get the C-washers out. It is good practice to always replace the seals with highquality replacements any time the axle is disassembled.

The end of the axle has a relief or notch machined into it to accommodate the C-washer. Keep in mind that this is the only thing holding the axle and wheel in place laterally on most beam-axle vehicles.

Carefully inspect the axle shafts in the seal and bearing area, especially if you are going to re-use them. Refer to Chapter 7 for more details on this inspection.

 

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At this point, you may want to check the gear pattern and backlash before the axle is disassembled any further. (Backlash and pattern checks are discussed in detail in Chapter 6.) This is only required if you are planning to re-use these components, and this information can be helpful to identify a problem area. Now you can re-install the differential pin and thread the retention bolt a few threads just to keep everything together. This step is not required, but it helps keep clutter to a minimum, which is especially important if you are working on multiple projects at once.

The ring gear and differential bearing caps are next in line to be removed. These caps are like engine main bearing caps and are machined in place, so mark them before removal to make certain they are returned to the correct orientation.

 

The C-washer can be difficult to grab and extract from inside the differential. Needle-nose-style pliers can be helpful or a simple magnet on a stick like this green unit work quite well for this task. (Randall Shafer)

The C-washer can be difficult to grab and extract from inside the differential. Needle-nose-style pliers can be helpful or a simple magnet on a stick like this green unit work quite well for this task. (Randall Shafer)

 

1)As you remove the axle shafts from the housing, it is always a good idea to support them with two hands. This stops the spline end from falling in the axle tube and dragging across the tube, wheel bearing, and seal. The seals will be replaced as a matter of course. (Randall Shafer)

1) As you remove the axle shafts from the housing, it is always a good idea to support them with two hands. This stops the spline end from falling in the axle tube and dragging across the tube, wheel bearing, and seal. The seals will be replaced as a matter of course. (Randall Shafer)

 

The C-washer slides into the groove that is machined into the end of the axle shaft. This groove is just past the splines and retains the axle shafts in the housing. (Randall Shafer)

The C-washer slides into the groove that is machined into the end of the axle shaft. This groove is just past the splines and retains the axle shafts in the housing. (Randall Shafer)

 

Mark the bearing caps and housing so you know which side they came from. You need to mark them so you know which end is up. These caps must go back in place exactly as they were removed; they are machined in place with the housing. (Randall Shafer)

Mark the bearing caps and housing so you know which side they came from. You need to mark them so you know which end is up. These caps must go back in place exactly as they were removed; they are machined in place with the housing. (Randall Shafer)

 

The differential case bearings are preloaded, and therefore installed with an interference fit, so they can be difficult to remove and install. The beveled edge of the shim is installed toward the axle housing. You want to have the full surface against the bearing cone. (Randall Shafer)

The differential case bearings are preloaded, and therefore installed with an interference fit, so they can be difficult to remove and install. The beveled edge of the shim is installed toward the axle housing. You want to have the full surface against the bearing cone. (Randall Shafer)

 

Since the differential is installed with an interference fit, it can be difficult to remove. Usually prying is required to remove the differential, but you need to be careful here and not pry on the ring gear teeth. There is a high probability if creating micro fractures and cracks or damaging the tooth contact surface. Also, if you are performing this step while the axle is still in the vehicle, be careful that the differential does not fall out of the axle and hit the ground. This is a sure recipe for damaging the gear teeth.

Since the differential is installed with an interference fit, it can be difficult to remove. Usually prying is required to remove the differential, but you need to be careful here and not pry on the ring gear teeth. There is a high probability if creating micro fractures and cracks or damaging the tooth contact surface. Also, if you are performing this step while the axle is still in the vehicle, be careful that the differential does not fall out of the axle and hit the ground. This is a sure recipe for damaging the gear teeth.

 

Once the differential and ring gear are removed, you should have a good view of the pinion head. This factory gear actually has the 3.73:1 ratio stamped into the pinion head along with the part number. (Randall Shafer)

Once the differential and ring gear are removed, you should have a good view of the pinion head. This factory gear actually has the 3.73:1 ratio stamped into the pinion head along with the part number. (Randall Shafer)

 

The transmission tool simply slips in the end of the transmission and stops the fluid from draining out. According to NHRA regulations, a driveshaft safety loop needs to be installed on this vehicle. (Randall Shafer)

The transmission tool simply slips in the end of the transmission and stops the fluid from draining out. According to NHRA regulations, a driveshaft safety loop needs to be installed on this vehicle. (Randall Shafer)

 

This tool is a plastic plug of the proper size and can be helpful to keep the transmission from leaking fluid once the driveshaft has been removed. (You can purchase an assortment of these to cover most common applications.) An old driveshaft can work or even a small plastic bag that is held in place with a rubber band can work in the short term. (Randall Shafer)

This tool is a plastic plug of the proper size and can be helpful to keep the transmission from leaking fluid once the driveshaft has been removed. (You can purchase an assortment of these to cover most common applications.) An old driveshaft can work or even a small plastic bag that is held in place with a rubber band can work in the short term. (Randall Shafer)

 

An air impact gun is used to remove the pinion nut. We just need to lightly grab the pinion flange in order to stop it from rotating, which makes quick work of removing the pinion nut.

An air impact gun is used to remove the pinion nut. We just need to lightly grab the pinion flange in order to stop it from rotating, which makes quick work of removing the pinion nut.

 

Since the pinion spline typically has a slight helix, the flanges may require a puller to remove them. You can fabricate this tool for the GM half-round-style pinion flange. It is a 3 x 4-inch piece of steel stock with the bolt pattern drilled in and nut welded in the center. This unit has a dual pattern for multiple-size U-joints.

Since the pinion spline typically has a slight helix, the flanges may require a puller to remove them. You can fabricate this tool for the GM half-round-style pinion flange. It is a 3 x 4-inch piece of steel stock with the bolt pattern drilled in and nut welded in the center. This unit has a dual pattern for multiple-size U-joints.

 

At times, the pinion may require some force to overcome the bearing fits. Here we left the pinion nut partially threaded in place to keep the pinion from completely coming out the other end of the axle. (Randall Shafer)

At times, the pinion may require some force to overcome the bearing fits. Here we left the pinion nut partially threaded in place to keep the pinion from completely coming out the other end of the axle. (Randall Shafer)

 

Depending on the flange type, you may be able to use a traditional jaw-style puller. The GM half-round requires a tool that bolts to flange, and the center bolt actually extracts the flange. This tool uses the same working principle as a harmonic balancer remover for an engine.

Depending on the flange type, you may be able to use a traditional jaw-style puller. The GM half-round requires a tool that bolts to flange, and the center bolt actually extracts the flange. This tool uses the same working principle as a harmonic balancer remover for an engine.

 

Once the pinion is removed, the bearing races or cones can be easily seen. The top port in the housing is what feeds the bearing with oil while the port on the lower left is the return port.

Once the pinion is removed, the bearing races or cones can be easily seen. The top port in the housing is what feeds the bearing with oil while the port on the lower left is the return port.

 

You need a long punch and hammer to drive the pinion head bearing race out of the housing from the front of the axle. (Randall Shafer)

You need a long punch and hammer to drive the pinion head bearing race out of the housing from the front of the axle. (Randall Shafer)

 

Drive out the pinion tail bearing race from inside the axle housing. Again, you need a suitable-length punch and hammer. When performing this step in the vehicle, it may be difficult to get a straight shot to hammer the punch. Be careful; you do not want to accidently hit the suspension components or dent the fuel tank. (Randall Shafer)

Drive out the pinion tail bearing race from inside the axle housing. Again, you need a suitable-length punch and hammer. When performing this step in the vehicle, it may be difficult to get a straight shot to hammer the punch. Be careful; you do not want to accidently hit the suspension components or dent the fuel tank. (Randall Shafer)

 

Once all of the gears and bearing races have been removed, you should be left with just the cast center section. On this unit, the magnetic fill plug is still in place as seen in the 10 o’clock position. Notice that there is metal debris stuck to it that needs to be cleaned off. (Randall Shafer)

Once all of the gears and bearing races have been removed, you should be left with just the cast center section. On this unit, the magnetic fill plug is still in place as seen in the 10 o’clock position. Notice that there is metal debris stuck to it that needs to be cleaned off. (Randall Shafer)

 

Now remove the differential carrier and ring gear assembly. Be careful here because this is a heavy piece. If you are uncomfortable doing the removal yourself, get some help. Compounding the difficulty, the differential should be preloaded or have an interference fit to the axle housing that prevents it from being easily removed. If you look closely, you should be able to see the shims between the bearing races and the housing. Now pry the differential case out of the axle. You can typically place the end of a prybar in the window of the differential case to help pry the assembly out. Or you can pry on the ring gear mounting bolts and the axle housing. Just don’t pry on the ring gear teeth because you may damage them. Also, be prepared for the weight of the unit when it comes out. You don’t want it to fall on the ground.

You need to keep track of which side the shims came from. This is important later when you re-assemble the axle. At this point, you should have a good view of the last internal gear left in the axle housing.

In order to remove the pinion, first remove the driveshaft. On most vehicles, this is bolted to the pinion axle flange and its opposite end just slips into the back of the transmission. It is a good idea to mark the position of the propshaft flange relative to the axle flange. From the vehicle assembly plant, the axle and propshaft imbalances are offset to cancel any vibrations. (For more information on propshaft joint styles, see Chapter 8.)

Now simply unbolt the propshaft from the axle flange (some prying may be required for removal) and then slide the yoke out of the transmission. When the yoke comes out of the transmission, chances are that the transmission will begin leaking fluid. Be prepared for this with your drain pan. You can slide a plastic cap tool in place to stop the transmission from draining.

You can even leave the propshaft in the transmission; just move the axle end portion of it out of the way and secure it there.

Before we remove the last part of the geared axle assembly we need to loosen the pinion flange nut.

Once the nut is removed the flange can be removed. On some axles the flange slides off, but most require some force. There are two methods for removing a stubborn flange. The first is to use a puller tool.

The second method is to use a punch on the pinion to drive the pinion into the axle and subsequently off the flange. This will probably damage the bearings but you should replace them anyway. If you use this method, make certain that you support and grab the pinion from inside the axle. As always, do not let these parts to fall on the ground, which will surely damage the gear teeth. Once the flange is removed, you can slide the pinion out with the head bearing and the crush sleeve still in place.

Now that the pinion is out, you have access to the bearing cones and pinion seal.

 

Use a large pry bar or even an old axle shaft to remove the axle shaft wheel end. Chances are pretty good that your wheel end and brakes are rusty and dusty like the axle, so you may need to replace some of this hardware.  (Randall Shafer)

Use a large pry bar or even an old axle shaft to remove the axle shaft wheel end. Chances are pretty good that your wheel end and brakes are rusty and dusty like the axle, so you may need to replace some of this hardware. (Randall Shafer)

 

The wheel end bearing can be tricky toremove. With this foot, the tool sneaks behind the bearing, so you can remove it. (Randall Shafer)

The wheel end bearing can be tricky toremove. With this foot, the tool sneaks behind the bearing, so you can remove it. (Randall Shafer)

 

The foot on the tool swivels and slides inside the bearing. Once past the bearing, the foot folds down and catches on the bearing. (Randall Shafer)

The foot on the tool swivels and slides inside the bearing. Once past the bearing, the foot folds down and catches on the bearing. (Randall Shafer)

 

The foot will firmly catch on the backside of the bearing race, so you can remove the bearing. (Randall Shafer)

The foot will firmly catch on the backside of the bearing race, so you can remove the bearing. (Randall Shafer)

 

It is just a matter of a few hits with the slide hammer and the bearing will usually pop out. Some of the more stubborn bearings require more effort, but this large slide hammer makes quick work of removing the bearing. It sure beats trying to cut and grind the bearing out. (Randall Shafer)

It is just a matter of a few hits with the slide hammer and the bearing will usually pop out. Some of the more stubborn bearings require more effort, but this large slide hammer makes quick work of removing the bearing. It sure beats trying to cut and grind the bearing out. (Randall Shafer)

 

Once the bearing and seal are removed, you should have a clear view of the inside of the axle tube.(Randall Shafer)

Once the bearing and seal are removed, you should have a clear view of the inside of the axle tube.(Randall Shafer)

 

Place this type of bearing removal tool around the back side of the bearing race, and tighten the two halves together. Pull just on the race and not the roller or cage. This tool works well when you can get behind the bearing race. (Randall Shafer)

Place this type of bearing removal tool around the back side of the bearing race, and tighten the two halves together. Pull just on the race and not the roller or cage. This tool works well when you can get behind the bearing race. (Randall Shafer)

 

This multi-piece clamshell-style bearing-removal tool works great. This specialized tool is just for pinion bearings. Here the tool is partially installed so you can see the clamshell portion. (Randall Shafer)

This multi-piece clamshell-style bearing-removal tool works great. This specialized tool is just for pinion bearings. Here the tool is partially installed so you can see the clamshell portion. (Randall Shafer)

 

Once both of the clamshell halves are in place, an outer sleeve (blue collar) is installed, which keeps the halves in place while you remove the bearing.(Randall Shafer)

Once both of the clamshell halves are in place, an outer sleeve (blue collar) is installed, which keeps the halves in place while you remove the bearing.(Randall Shafer)

 

Use standard micrometers to precisely measure the thickness of the pinion head bearing shim. Make sure you get an accurate measurement of this shim as this shim thickness will be adjusted by very small increments of 0.002 inch. (Randall Shafer)

Use standard micrometers to precisely measure the thickness of the pinion head bearing shim. Make sure you get an accurate measurement of this shim as this shim thickness will be adjusted by very small increments of 0.002 inch. (Randall Shafer)

 

Now you can thread the lead screw and the tool draws the bearing off the pinion head as you tighten the bolt. Here, we are using an air impact gun to rapidly remove thread the lead screw. This is similar to the function of most typical bearing pullers. (Randall Shafer)

Now you can thread the lead screw and the tool draws the bearing off the pinion head as you tighten the bolt. Here, we are using an air impact gun to rapidly remove thread the lead screw. This is similar to the function of most typical bearing pullers. (Randall Shafer)

 

Once the pinion head has been removed, you should see the head bearing shim. Look closely, the shim is thin and may stick to the pinion head from the oil and blend in. (Randall Shafer)

Once the pinion head has been removed, you should see the head bearing shim. Look closely, the shim is thin and may stick to the pinion head from the oil and blend in. (Randall Shafer)

 

The best way to remove the bearing races from the axle housing is to use a punch and drive them out from the opposite end. The pinion seal can be removed with a pry tool or driven out with the pinion tail bearing race.

Now the center section of the axle should be completely disassembled. The remaining parts installed on the axle are the wheel-end bearings and seals. The seals can be pried out, just like the pinion seal above.

Now you can access the wheelend bearings, which are cylindrical roller bearings. The axle shaft is the inner bearing race, so with the axles removed, you can see the rollers. We are using a tool with a foot inserted behind the bearing to apply the force necessary for removal.

This tool has a slide hammer on the other end to allow removal of the bearing.

Usually, bearings pop right out with a few strikes from the slide hammer.

At this point, the axle’s internals have been completely disassembled and are almost ready for cleaning. Before I cover cleaning, let’s remove the final bearings from the differential case and pinion shaft. The tapered roller bearing can be removed in a few ways. The destructive method is to cut the cage with a set of side cutters and remove the cage and rollers. Then cut off the inner race with a small cutoff wheel tool. Cut the race at a 45-degree angle to avoid the cutter wheel nicking the gear or differential case. Another method is to use any one of a variety of bearing tools.

Or, you can remove the pinion bearings with the clamshell-style tool. This tool is very helpful but not everyone has one. If you are going to be working on many axles, you can probably justify the expense of such a tool.

The main reason to remove the bearing, besides the obvious goal of replacing the bearing, is to gain access to the pinion head shim.

Most pinions have the shim behind the bearing to properly locate the pinion. Dana axles are an exception, where the shim is located between the pinion bearing race and the axle housing itself. Even some of the newer Dana axles have pinion shims behind the head bearing on the pinion and behind the head bearing race in the housing. Now is a good time to measure the thickness using a micrometer, and record it. (For more information on shims and gear patterns, see Chapter 6.)

The differential bearings can typically be removed with a bearing spreader or cut off as described above. (For instructions on ring gear removal, see Chapter 6.)

 

Cleaning and Inspection

Start from the inside and work your way out in the cleaning process. I use a liberal amount of cleaning solvent in this process. Brake cleaner is a good choice because it does not leave a residue. Spray the entire inside of the axle housing, taking special attention to clean the lube ports for the pinion and all of the bolt holes.

 

Liberal amounts of cleaning solvent should be sprayed inside the housing to thoroughly rinse out debris and oil. We like to use brake cleaner because it is relatively inexpensive and dries without leaving a film. (Randall Shafer)

Liberal amounts of cleaning solvent should be sprayed inside the housing to thoroughly rinse out debris and oil. We like to use brake cleaner because it is relatively inexpensive and dries without leaving a film. (Randall Shafer)

 

Standard shop rags and a long bar work great to clean the inside of the axle tubes. This is similar to cleaning a gun barrel. We thoroughly wet down the rag with solvent and push it in the axle tube. (Randall Shafer)

Standard shop rags and a long bar work great to clean the inside of the axle tubes. This is similar to cleaning a gun barrel. We thoroughly wet down the rag with solvent and push it in the axle tube. (Randall Shafer)

 

We first remove the old sealant, clean out the old thread holes, rinse every-thing, and finally blow everything dry with shop air. This ensures that we have a good clean surface to seal the cover back in place. (Randall Shafer)

We first remove the old sealant, clean out the old thread holes, rinse every-thing, and finally blow everything dry with shop air. This ensures that we have a good clean surface to seal the cover back in place. (Randall Shafer)

 

We keep pushing shop rags through the tubes until they no longer are dirty. Just like a surgeon does, we need to make sure that all of the rags are accounted for. We do not want to leave one inside the axle tube.(Randall Shafer)

We keep pushing shop rags through the tubes until they no longer are dirty. Just like a surgeon does, we need to make sure that all of the rags are accounted for. We do not want to leave one inside the axle tube.(Randall Shafer)

 

This bearing driver tool is the correct diameter to match the bearing. With this type of tool, it’s far easier to get the bearing straight during installation and the process goes quickly. We can even have the other bearing on our finger, so we just go to the other side and quickly install it. (Randall Shafer)

This bearing driver tool is the correct diameter to match the bearing. With this type of tool, it’s far easier to get the bearing straight during installation and the process goes quickly. We can even have the other bearing on our finger, so we just go to the other side and quickly install it. (Randall Shafer)

 

The wheel end bearing should be driven to the shoulder. Notice that the bearing is below the end of the axle housing tube. The seal is pressed into place on the extra part of the tube. (Randall Shafer)

The wheel end bearing should be driven to the shoulder. Notice that the bearing is below the end of the axle housing tube. The seal is pressed into place on the extra part of the tube.
(Randall Shafer)

 

If you do not have the correct size of bearing race driver tool, you can use a punch to install the pinion bearing races. Alternate between top, bottom, and side to side in order to drive the race straight in the housing. You should hear a definite solid sound as you fully seat the race. Make sure that you are tapping on the edge of the race and not the bearing running surface. (Randall Shafer)

If you do not have the correct size of bearing race driver tool, you can use a punch to install the pinion bearing races. Alternate between top, bottom, and side to side in order to drive the race straight in the housing. You should hear a definite solid sound as you fully seat the race. Make sure that you are tapping on the edge of the race and not the bearing running surface. (Randall Shafer)

 

We want to pre-lube the wheel end seal with grease before installation. We need to grease the surface that will be in contact with the axle shaft.(Randall Shafer)

We want to pre-lube the wheel end seal with grease before installation. We need to grease the surface that will be in contact with the axle shaft.(Randall Shafer)

 

In order to avoid any types of leaks, we apply a sealant to the outside diameter of the seal surface, which is the part of the seal that will be in contact with the housing. (Randall Shafer)

In order to avoid any types of leaks, we apply a sealant to the outside diameter of the seal surface, which is the part of the seal that will be in contact with the housing. (Randall Shafer)

 

Here we are using a hammer to drive the seal into place. Care must be taken to not tilt the seal during installation. A seal driver can also be used for this task. (Randall Shafer

Here we are using a hammer to drive the seal into place. Care must be taken to not tilt the seal during installation. A seal driver can also be used for this task. (Randall Shafer)

 

The seal has been properly installed flush with the end of the axle tube. Now you repeat the bearing and seal installation for the other side of the axle. (Randall Shafer)

The seal has been properly installed flush with the end of the axle tube. Now you repeat the bearing and seal installation for the other side of the axle. (Randall Shafer)

 

Just as with the wheel end seals, you grease the pinion seal inner lip before installation. This seal also has a lip to make it easier to install. You just need to install it flush with the housing. (Randall Shafer)

Just as with the wheel end seals, you grease the pinion seal inner lip before installation. This seal also has a lip to make it easier to install. You just need to install it flush with the housing. (Randall Shafer)

 

As before, apply some RTV to the outer edge of the seal to fill in any damaged areas on the housing. This extra step goes a long way to avoid leaks. (Randall Shafer)

As before, apply some RTV to the outer edge of the seal to fill in any damaged areas on the housing. This extra step goes a long way to avoid leaks. (Randall Shafer)

 

Once properly installed, the pinion seal should look like this. Notice that the pinion tail bearing is now trapped in place. This means that you installed the tail bearing before the seal. (Randall Shafer)

Once properly installed, the pinion seal should look like this. Notice that the pinion tail bearing is now trapped in place. This means that you installed the tail bearing before the seal. (Randall Shafer)

 

The pinion head bearing is pressed onto the pinion stem. Notice that we are using a traditional hydraulic press and an old bearing inner race as a guide to press on the new bearing. As you accumulate old bearings, you can use them as press tools. We already had the pinion shim on the shaft before we installed the bearing.

The pinion head bearing is pressed onto the pinion stem. Notice that we are using a traditional hydraulic press and an old bearing inner race as a guide to press on the new bearing. As you accumulate old bearings, you can use them as press tools. We already had the pinion shim on the shaft before we installed the bearing.

 

We are pushing the pinion in from the open end of the axle and installing the flange from the other end. On some axles, like the GM 12-bolt, the pinion is a very tight fit to the tail bearing and you will need to tap the flange on while holding the pinion. (Randall Shafer)

We are pushing the pinion in from the open end of the axle and installing the flange from the other end. On some axles, like the GM 12-bolt, the pinion is a very tight fit to the tail bearing and you will need to tap the flange on while holding the pinion.(Randall Shafer)

 

Here is the pinion ready to install into the axle housing. Notice that the shim, head bearing, and new crush sleeve were already installed prior to putting the pinion in the axle housing.(Randall Shafer)

Here is the pinion ready to install into the axle housing. Notice that the shim, head bearing, and new crush sleeve were already installed prior to putting the pinion in the axle housing.(Randall Shafer)

 

Now clean off the cover sealing surface. It is important to get this surface clean and free of any old gasket material and oil. This helps ensure a good seal surface for the gasket or RTV. Perform a similar operation on the wheel end and inside the axle tubes. Thoroughly rinse the seal and bearing bores on the wheel ends and then rinse the inside of the axle tubes. Wet down rags with solvent and push them down the axle tubes and retrieve them from the center section of the axle. Do this a few times on each axle tube to make certain that they are clean. You can use a long screwdriver or even a broom handle to push the rag down the tube.

Give the internal section another final rinse of solvent and blow it out with shop air. You can’t make things too clean here.

 

MuscleCarB

 
 
 

Axle Reassembly

The wheel ends can be tackled next. First, drive each bearing into the axle housing until it is completely seated.

Then the seals can be installed. Grease or liberally apply gear lube on the inside of the seal lip before installation.

Then apply RTV sealant to the outside surface of the seal.

Now the seal can be driven into the axle housing.

With the wheel end completed, concentrate on assembling the gears and differential. First, drive the pinion bearing races into the axle housing.Just line up the bearing races and, with a suitable size punch, drive them into place. Tap evenly around the race in order to install it straight.

You need to repeat this procedure for the pinion tail bearing race on the front of the axle. Now set the pinion tail bearing in place. Be sure to lightly lubricate it, along with every subsequent bearing you install, with the correct gear oil. At this point, the pinion seal can be installed.

Notice that the pinion seal keeps the bearing in place. You can no longer remove the pinion tail bearing without removing the seal first. Put the correct shim on the pinion and press the pinion bearing in place. Be careful here to make sure that you press on the bearing inner race and not the cage.

Next, install a new crush sleeve. Now you can reinstall the pinion into the axle housing.

 

Since there are no shims behind the differential bearings, we need to make certain to fully seat them. Again, we are using an old inner bearing race as a spacer to press the new bearing in place. These are just the right size to make certain that we do not accidentally press on the bearing cages. (Randall Shafer)

Since there are no shims behind the differential bearings, we need to make certain to fully seat them. Again, we are using an old inner bearing race as a spacer to press the new bearing in place. These are just the right size to make certain that we do not accidentally press on the bearing cages. (Randall Shafer)

 

The differential is partially installed in the axle housing. The bearing cups are in the axle housing, and we are lightly prying the bearing in place to allow access to push the shim in place. This is one of the more difficult tasks and requires some finesse. (Randall Shafer)

The differential is partially installed in the axle housing. The bearing cups are in the axle housing, and we are lightly prying the bearing in place to allow access to push the shim in place. This is one of the more difficult tasks and requires some finesse. (Randall Shafer)

 

The shim has a light-green stripe painted on it and is partially inserted in place at an angle. At this point, you should get the other side shim in place. The beveled edge of the shim goes toward the housing. (Randall Shafer)

The shim has a light-green stripe painted on it and is partially inserted in place at an angle. At this point, you should get the other side shim in place. The beveled edge of the shim goes toward the housing. (Randall Shafer)

 

This tool can be homemade; it is basically a semi-circle that matches the shim diameter cut out of a piece of flat steel plate. These tools are also available from most axle parts suppliers but not typical auto parts stores, so you want to plan ahead. The tool drives the shims into place. Then the plate just needs to be trimmed like this one. After some use, the end mushrooms over, which can easily be ground off.

This tool can be homemade; it is basically a semi-circle that matches the shim diameter cut out of a piece of flat steel plate. These tools are also available from most axle parts suppliers but not typical auto parts stores, so you want to plan ahead. The tool drives the shims into place. Then the plate just needs to be trimmed like this one. After some use, the end mushrooms over, which can easily be ground off.

 

Here is another option to drive the shims and bearings home. Notice that this tool has GM 12-bolt stamped on it. We are using it on a Ford 8.8-inch axle. Both axles are quite similar and actually use the same bearings, and there-fore, one tool works for both. You want to make sure that the bearing and shims are fully seated. (Randall Shafer)

Here is another option to drive the shims and bearings home. Notice that this tool has GM 12-bolt stamped on it. We are using it on a Ford 8.8-inch axle. Both axles are quite similar and actually use the same bearings, and there-fore, one tool works for both. You want to make sure that the bearing and shims are fully seated. (Randall Shafer)

 

Once the shims and bearings are in place, we can install the caps and torque the bolts. Just as with any other fastener, tighten the fastener in stages. (Randall Shafer)

Once the shims and bearings are in place, we can install the caps and torque the bolts. Just as with any other fastener, tighten the fastener in stages. (Randall Shafer)

 

A billet bearing cap for a GM 12-bolt rear axle is on the left; the OEM cap is on the right. Mark Williams Enterprises made the billet cap, which requires machining to fit the axle and cannot be installed out of the box.

A billet bearing cap for a GM 12-bolt rear axle is on the left; the OEM cap is on the right. Mark Williams Enterprises made the billet cap, which requires machining to fit the axle and cannot be installed out of the box.

 

The factory stamped-steel cover is on the right; an aluminum structural cover is on the left. Notice the fill and drain plugs (top and bottom) along with the bearing cap preload bolts at the 3 and 9 o’clock positions.  (Randall Shafer)

The factory stamped-steel cover is on the right; an aluminum structural cover is on the left. Notice the fill and drain plugs (top and bottom) along with the bearing cap preload bolts at the 3 and 9 o’clock positions. (Randall Shafer)

 

On the inside of the structural cover you again can see the bearing preload pads that are adjusted after the cover is installed. These structural covers are a great upgrade to the axle. (Randall Shafer)

On the inside of the structural cover you again can see the bearing preload pads that are adjusted after the cover is installed. These structural covers are a great upgrade to the axle. (Randall Shafer)

 

Some of these covers even come with cooling fins to help reduce the lube temperatures. This unit comes painted.

Some of these covers even come with cooling fins to help reduce the lube temperatures. This unit comes painted.

 

The covers can also incorporate lube-level dipsticks. This is neat but not required. How often do you check your axle oil level, or need to?

The covers can also incorporate lube-level dipsticks. This is neat but not required. How often do you check your axle oil level, or need to?

 

Apply a small amount of RTV on the flange spline area. This keeps oil from wicking past the splines and leaking later. Then slip the flange on the pinion, install the nut, and tighten until you achieve the correct pinion bearing preload (see Chapter 6). One method to make certain that the bearing races are completely seated is to tighten the pinion nut until the correct preload is achieved and then with a soft punch (usually brass or aluminum), tap the pinion head, not the teeth, and the opposite side of the pinion stem into the axle housing. Then check the pinion torque-to-turn again and adjust accordingly.

Next, install the bearings on the differential case. There are no shims behind these bearings.

Now you just need to install the ring gear. Notice that the ring gear slips over most of the differential case; only the last 1/2 inch is a slight press fit that locates the gear relative to the carrier. Slip the ring over the differential case, start threading the bolts to make certain that the holes are lined up, and press it into place. (Refer to Chapter 6 for the detailed steps required to properly install the ring gear.)

With the ring gear bolted to the differential, install the differential assembly with the proper shims in the axle housing. As it was to remove, the differential assembly can be a little tricky to install because of its weight and the slight interference fit between the shims and the housing. It is helpful to first place the differential loosely in the axle housing, and set the bearing cups and shims in place.

Push the differential in place and be careful that the shims don’t fall out. This can be difficult and usually the shims need to be tipped in slightly.

Once everything is in place, use a tool to tap the shims and bearing into place.

Now install the bearing caps in their correct location and torque them accordingly.

It is a good idea to double-check the backlash and pattern at this point, just to be on the safe side.

There are some companies that sell aftermarket billet bearing caps for popular axles. The cap should be installed on the ring gear side (driver’s side) of the axle where the highest forces are reacted. These are not direct bolt-up parts. Just as the axle manufacturer machines the OEM bearing caps at assembly, a replacement cap must also be machined to fit properly.

If the differential pin is installed, temporarily remove it. Carefully slide the axle shafts into the axle tubes, making certain to guide them over the new wheel-end seals and bearings. You don’t want the axle shaft spline to damage the new seals. Once the axle shafts are lined up with the side gears and installed deep enough to expose the C-washer groove, simply install the C-washers and push the shafts back outboard. This allows the C-washers to fully seat in the counter bores in the side gears. Repeat for the other side and then install the differential pin and differential pin retaining bolt. Make sure that you use thread locker on the differential pin bolt and torque accordingly.

 

When the preload bolts are completely loosened from the outside, the stud should stick out like this. Notice the jam nut on the stud; this will be important to maintain the correct adjustment later. (Randall Shafer)

When the preload bolts are completely loosened from the outside, the stud should stick out like this. Notice the jam nut on the stud; this will be important to maintain the correct adjustment later. (Randall Shafer)

 

Here is a view of the bearing cap preload pads from inside the cover. They should not contact the bearing caps at this point. (Randall Shafer)

Here is a view of the bearing cap preload pads from inside the cover. They should not contact the bearing caps at this point. (Randall Shafer)

 

Make certain that you have the correct cover for your application. Here, you can see the depth difference of two covers for the same axle. One vehicle application has a panhard bar for the suspension while the other does not. The panhard bar application requires a shorter cover.

Make certain that you have the correct cover for your application. Here, you can see the depth difference of two covers for the same axle. One vehicle application has a panhard bar for the suspension while the other does not. The panhard bar application requires a shorter cover.

 

Some gasket adhesive is applied to the cover surface, so the gasket stays in place during installation for a good seal. (Randall Shafer)

Some gasket adhesive is applied to the cover surface, so the gasket stays in place during installation for a good seal. (Randall Shafer)

 

We also apply the gasket adhesive on the axle housing. The black horizontal bar is the rear anti-sway bar and makes the cover a little more complicated to install. (Randall Shafer)

We also apply the gasket adhesive on the axle housing. The black horizontal bar is the rear anti-sway bar and makes the cover a little more complicated to install. (Randall Shafer)

 

Once the gasket is set in place on the cover, we are ready to install the cover on the axle housing, so we put a couple of bolts in the holes to help line it up. (Randall Shafer)

Once the gasket is set in place on the cover, we are ready to install the cover on the axle housing, so we put a couple of bolts in the holes to help line it up. (Randall Shafer)

 

For the bearing preload bolts, we apply some black RTV on both of them. We removed the jam nuts at this stage in order to gain clear access to the threads. (Randall Shafer)

For the bearing preload bolts, we apply some black RTV on both of them. We removed the jam nuts at this stage in order to gain clear access to the threads. (Randall Shafer)

 

Here is the cover in place with some of the bolts started. Again, note the washers under the bolts and the fill and drain plugs. (Randall Shafer)

Here is the cover in place with some of the bolts started. Again, note the washers under the bolts and the fill and drain plugs. (Randall Shafer)

 

We are now ready to tighten the preload bolts to the correct specification, then holding them in place while we tighten the jam nuts. Notice that we use a unique socket with a hex on the back end that allows for a boxed end wrench and still allows the hex wrench to be inserted in the center.(Randall Shafer)

We are now ready to tighten the preload bolts to the correct specification, then holding them in place while we tighten the jam nuts. Notice that we use a unique socket with a hex on the back end that allows for a boxed end wrench and still allows the hex wrench to be inserted in the center.(Randall Shafer)

 

The typical stock fill plug location is on the front side of the pinion portion of the housing. It's typically on the forward-facing surface of the axle and has a square drive that requires a 3/8-inch ratchet extension to access them. Make certain that you clean the internal square of rust and grime and lightly tap in the extension before you attempt to loosen it. They can be stubborn at times, and you do not want to strip out the square drive.(Randall Shafer)

The typical stock fill plug location is on the front side of the pinion portion of the housing. It’s typically on the forward-facing surface of the axle and has a square drive that requires a 3/8-inch ratchet extension to access them. Make certain that you clean the internal square of rust and grime and lightly tap in the extension before you attempt to loosen it. They can be stubborn at times, and you do not want to strip out the square drive.(Randall Shafer)

 

Adding a replacement structural cover helps support the bearing caps and the axle housing. Think of the axle as a box without a lid on it. The box is not very strong until there is a lid properly attached to it. Castaluminum aftermarket covers can provide that additional support and structural integrity. The stock stamped steel covers provide some support, but very little when compared to the aluminum covers. Furthermore, many of the aftermarket structural covers are equipped with a drain plug for convenient fluid removal.

Whether you choose to re-use the old cover or upgrade to a structural cover, you need to seal the cover back to the axle. This is a great upgrade that you may want to perform on your axle during a normal lube change. The structural covers typically provide better fill and drain plugs, better cooling, and more lube capacity plus the additional structure. These covers are factoryinstalled on many of the larger truck axles. Most kits come with a replacement gasket, but keep in mind that most axles from the factory are just sealed with gasket sealer. Make sure that both surfaces are clean of any old sealant, gasket material, and gear oil.

For the structural cover, we chose to use the gasket. We first loosened the bearing caps preload fasteners, Later, these preload bolts will be lightly tightened to provide additional support between the bearing caps and the cover, after the perimeter bolts are tightened.

We sprayed a gasket adhesive on the axle housing and cover to help hold the gasket in place during installation.

Now it is simply a matter of installing the cover and bolts. Don’t forget to put washers under the heads of bolts. Then torque them to the required specification.

Apply sealant to all of the threads on the cover. Remove the drain plug and apply a dab of RTV sealant on the threads. You need only a pea-size amount to do the trick.

Now set the bearing cap preload. Apply some RTV to these threads.

The last step is to fill the axle with the correct amount and type of lubricant. Don’t forget to add friction modifier if your differential requires it. (See Chapter 6 for more information on gear oil and friction modifiers along with proper break-in procedures.)

Re-install the fill plug and install the drums and wheels. Torque the lug nuts and lower the vehicle to the ground.

 

Summary

You have been shown the major and minor steps required to completely disassemble, clean, and reassemble a typical beam axle. You can see that it is a fair amount of work, and this work needs to be performed carefully in order to obtain ideal results. The details are very important but the task is very achievable with the correct tools and time for the job.

 

Written by Joe Palazzolo and Posted with Permission of CarTechBooks

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