Chrysler formed a manufacturing alliance with New Process in 1964, and from this alliance the A833 4-speed was created. Over the years, the transmission evolved, but it provided reliable and efficient performance until its discontinuance in 1979. The fully synchronized transmission was offered in most Chrysler cars, such as for A-, B-, C-, E-bodied cars from 1964 until the mid-1970s. During this time, the A833 established a reputation for outstanding performance and reliability.
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A tail-mounted shifter and retangular 10-bolt side cover clearly distinguishes the A833 transmission from many other manual transmissions. The A833 is a side-loaded transmission with all gears situated in the main case. In addition, the A833 has a 73⁄8-inch bell housing, and its internals are different than other gearboxes. By comparison, the T10 and Muncie 4-speeds use a reverse gearset outboard of the main case. The outboard design requires an additional mid plate. Use of the additional mid section can create stability and alignment issues. The A833 not only eliminated the mid section, but it added a larger center-to-center distance to the gearset. The T10 and Muncie had 3.25-inch center-to-centers. The A833 was elongated to 3.375 inches, and the A833 became the strongest 4-speed in its class. Not much time passed before people began adapting this transmission to other makes.
From 1975 on, Chrysler released an A833 with an overdrive gear for its range of manual-transmissionequipped vehicles. The New Process overdrive 4-speed was installed on cars, such as the 225 Slant Six Duster, for improved fuel efficiency. In the older four-speed gearbox, fourth gear had a 1:1 ratio, the new gearbox’s third gear became .73:1 for overdrive, and the forth gear remained 1:1 direct drive. The 3-4 shift lever was turned over to accommodate this new gearset arrangement.
Input shafts came with 23 or 18 splines. Output shafts in early versions had 23, 26, or 30 splines. Only 18-spline inputs came with 30-spline outputs. These were typically dubbed “Hemi” boxes. The 18-spline unit was used with 426 Wedge, 426 Hemi and 440 while the 23-spline shafts were used for 361, 383, 400, and other engines. As a note, if you want to swap the input shafts or gearsets, you can use the bearing retainer and front input bearing, which definitely saves times. It was easy to swap in an A833 for automatic-equipped Mopars and hence became a common procedure for muscle car owners.
These transmissions are cast-iron and very stout, and it is very important that you understand that these transmissions are extremely heavy. The A833 built through the 1960s and early 1970s were cast-iron; aluminum cases were introduced in the mid 1970s. These cast-iron units can weigh more than 115 pounds—a heavy transmission, such as this, if not supported correctly can break your fingers if it rolls onto them. Chrysler’s New Process Gear manufactured the A833. It was also the only transmission ever offered from the factory with slick-shifted gears. Besides incorporating the slick-shift process, race Hemi-style transmissions came with better alloy gears and bronze bushed speed gears to reduce frictional losses as well as gear-to-mainshaft seizures.
New Process Gear once touted itself as “The Largest Gear Manufacturer in the World.” Located slightly north of the city center of Syracuse, New York, this large manufacturing plant has now been converted to modernly appointed loft apartments. Interestingly, the company’s water tower still stands, rusting away, in the middle of it all. A company called Passon Performance has reproduced just about every part of the A833 transmission, which has been a major undertaking because so many variations exist. Popular race sets are available. For weight savings, all case configurations have been meticulously reproduced in aluminum—an iron A833 can tip the scales at 125 pounds.
General Motors also used aluminum and iron versions of the A833 from 1981 to1985. Many parts from these versions interchange with older units. Typically found in GMC Sierra pickups, the A833 was renamed the NP440 and has been a popular 4-speed conversion for GM muscle cars because it has the same bolt pattern and splines as a Muncie 4-speed. Step-by-step procedures and general parameters for rebuilding the A833 is covered here, but keep in mind, there are several variations in bearing combinations as well as types of side covers. Therefore, there may be some variation in the rebuilding procedures depending on the A833 you’re rebuilding.
For the most part, you can reverse the disassembly of the transmission to put it together. I’ve included some techniques that may help you make assembly a little easier. Installation of bushings, seals, and needle bearings have already been covered.
Step 1: Remove Side Cover
Use a ratchet and socket to remove the 12 bolts that secure the side cover to the case. Take note of where each bolt comes from, because some units have different length bolts for certain positions. Fish out the forks and check them for wear.
Step 2: Remove Front Bearing Retainer (Special Tool)
Remove the 4 bolts that hold the front bearing retainer. Use a snap-ring pliers to expand and remove the snap ring that locates the input shaft to the front bearing. My method for disassembly is based on the fact that most people do not have a special front bearing puller.
Step 3: Remove Speedometer Gear
Use a ratchet and socket or (as shown) a drill with a socket and extension to remove the bolt and hold-down for the speedometer gear. Take note of the location of the fitting, so you can easily install it when the time comes.
Step 4: Align Speedometer Gear (Important!)
The A833 uses an offset speedometer fitting for the speedo driven gear. The numbers correspond to the range of tooth counts for the gear. The raised index mark on the gear lines up with an alignment mark on the extension housing. You must reinstall this fitting in the correct position. If it is reinstalled in the wrong position, your speedometer will not to work or it will strip the gear.
Step 5: Remove Extension Housing Bolts
Unlike the Muncies and T10s, this extension actually holds the complete gear assembly. This design eliminates the mid plate bearing support and the extra parting line, so a stronger case is effectively built. It will not pull out, so don’t try to force it.
Step 6: Remove Countershaft
Pry on the extension housing with an old screwdriver just enough to break it free. Rotate it 180 degrees, so the countershaft is exposed. This allows you to remove it and drop the countergear out of the way of the upper geartrain.
Once you start removing the countershaft, support the countergear with your other hand to take pressure off the shaft. This helps it come out. These components are really heavy, so use work gloves rather than thin surgical gloves to protect your hands. There is a small woodruff key that will come out.
Step 7: Remove the Extension and Geartrain
With the countergear dropped, you can remove the extension and geartrain assembly.
Step 8: Drive Input 8 Shaft into Case
Use snap-ring pliers to remove the front bearing’s outer retaining snap ring and use a mallet to carefully tap the input shaft with the bearing through the case. Units that have the larger-style bearing are not able to use this technique. Instead keep the bearing supported by the outer ring on the case and press the input shaft of the bearing using the case as a support.
Step 9: A) Remove Countergear
Now you have a clean shot at removing the countergear. If you’re going to reuse the needles, you may want to do this over some sort of tray to avoid losing any. However, in many cases, it’s a good idea to replace the needles, especially if it is a highermileage transmission that is being rebuilt.
B) Broken Shifter Shaft
This unit has a broken reverse shifter shaft. It is quite common for these to strip and break because they have a very small 5/16-inch coarse thread. The reverse light switch is located here as well as the reverse detent fitting assembly.
Step 10: Remove Detent Assembly
I’ve removed the complete reverse detent assembly and reverse switch. These simply unscrew from the main case. Don’t bother trying to take the upper part of the detent assembly apart because it’s easier to do that off the transmission and supported firmly in a vice. A 3/8-inch detent ball and spring will fall out.
Step 11: Remove Reverse Idler Shaft
Punch out the reverse idler shaft. Sometimes a long punch or an offset pry bar will work when going in from the front of the case. This shaft also has a woodruff key. Notice the slot for it.
Step 12: Remove Reverse Idler Gear and Parts
Once the idler shaft has been removed, you can remove the reverse idler gear, reverse fork, and shifter shaft.
Step 13: Disengage Rear Bearing Retaining Ring
Start disassembling the upper geartrain by squeezing the rear bearing retaining ring ends together. You can use a regular set of adjustable pliers to do this. Move it forward to dislodge the retaining ring from the groove in the extension housing.
Step 14: Remove Output Shaft
Sometimes the bearing gets stuck in the bore, so gently tap the output shaft with a hammer to start removal. Be careful not to overdo it and damage the shaft.
As the whole output shaft assembly comes out of the tail, make sure you don’t knock off the 3-4 synchro hub. Some of the synchro strut keys are not readily available parts, so you don’t want to lose any of these keys.
Step 15: Remove 3-4 Synchro and Third Gear
Use a snap-ring pliers to remove the snap ring that secures the 3-4 synchro assembly and third gear to the mainshaft. Once the snap ring has been removed, the 3-4 synchro assembly and third gear slide off the mainshaft.
Step 16: Note Position of 3-4 Assembly (Documentation Required)
Once the 3-4 assembly has been removed, take note of the position of the slider because it needs to be assembled in the same position. The A833 later-style rings have the indexing dog built into the ring. This reduces side load on the strut key.
Step 17: Remove Rear 17 Bearing Snap Ring
Notice that the speedometer drive gear is actually part of the main shaft. This is a great design feature simply because you never have to pull the transmission apart for a speedometer gear failure.
Step 18: Press Off Rear Bearing
Support the assembly under first gear. You can use a press or just tap the output shaft to press off the rear bearing. An old Muncie case is used to support the main shaft, so the work can be performed.
Step 19: Remove FirstGear Synchro Ring
Once the rear bearing has been pressed off, the first gear and first-gear synchro ring simply slide off the mainshaft.
Step 20: Remove 1-2 Synchro Snap Ring
Use a snap-ring pliers to remove the 1-2 synchro snap ring. The complete 1-2 assembly, second-gear synchro ring, and second gear lift off the shaft once the snap ring has been removed.
Step 21: A) Press Off Input Shaft Bearing
Press off the input shaft bearing using a shop press. This image shows the smaller 307-style bearing. Other units have the larger 308SG8 bearing.
B) Bearing Styles
These are the two style bearings of the A833. Units can have two small- or two large-style bearings or a combination of small and large.
C) Synchro Assembly Parts
The hubs and sliders of both synchro assemblies are laid out, so you can see the correct order of these parts. The right side of the picture would be the rear of the transmission. Note that the hubs are offset toward the front. Notice that the 1-2 hub has a longer offset than the 3-4 hub. For complete synchro ring assembly instructions, refer to page 26.
The ring on the left is the later style that has a built-in dog; the early style is shown on the right. These rings use different strut keys and synchronizer assemblies. Because the transmissions are so old, it is not uncommon to see a mix of early and later assemblies in an A833.
Step 22: A) Install Side Cover
This side cover uses a comb detent and interlock system as on a Muncie 4-speed. I’ve chosen to use this cover in the buildup, but it is more difficult of the two styles to install.
B) Interlock System
This side cover uses a sprung-ball type of interlock similar to the ones used in all T10-style transmissions.
Step 23: Shift Fork Ends (Professional Mechanic Tip)
This image illustrates the two basic style shift fork ends. The fork on the left is iron and is used with the comb-style cover. The bronze fork on the right is used in the ball detent cover. I actually used an iron 3-4 T10 shift fork as a replacement for the bronze 3-4 fork. You simply space it in with hardened washers.
Step 24: Inspect Shifter Shaft
This shifter shaft shows wear at the end. If the linkage arm does not fit tight on the rectangular tab, it will always work loose. After inspecting the shafts, deburr the ends and replace the O-rings.
Step 25: A) Disassemble Reverse Detent
Secure the reverse detent in a vise and use a ratchet and socket to disassemble it.
B) Order of Countergear Bearings and Spacers
This is how the countergear needle bearings and spacers stack. Use assembly gel to hold the needles inside the gear.
Step 26: Inspect Reverse Gear
This design, which incorporates the reverse gear as part of the countergear, has at least one disadvantage. If the reverse section is damaged, you need to replace the entire countergear because reverse is a non-synchronized gear. After inspecting this gearing, we found out that it is still useable.
Step 1: Insert 1 Strut Keys in Hub
Use assembly gel to hold the strut keys in place in the hub. The later style can fall out of the hub if you move the slider to far.
Step 2:Align Synchro Ring with Slider
You need to catch the later-style synchro ring’s dog section in the key slot of the slider and hold the ring in place with assembly gel.
Step 3:Install Retaining Ring on Mainshaft
Remember to place the rear bearing retaining ring on the mainshaft before reinstalling a new rear bearing. It’s a lot easier to install it now than later in the process.
Step 4:Install Rear Bearing in Extension Housing
Support the output assembly in a vise. Always clean the rear housing bearing bore with emery cloth and then spray WD-40 in it, so the extension housing slides back onto the rear bearing much easier. You must compress the snap-ring tabs together to work it back into place.
Step 5: Seat Rear Bearing Retaining Ring
Use a small screwdriver to make sure the rear bearing retaining ring is fully seated in the extension housing.
Step 6: Install Fork, Idler Gear and Idler Shaft
Install a new O-ring on the reverse shifter shaft. In addition, install the fork, idler gear, and idler shaft. The fork groove of the idler gear faces toward the rear. Notice that I have installed the detent sleeve but have not fully assembled the rest of it.
Step 7: Install New Needle Bearings Inside 7 the Input Shaft
As seen in other transmission rebuilds in this book, use assembly grease to hold the needle bearing inside the input shaft. Place the input shaft on the front of the output shaft and push the 3-4 slider forward to keep them together. Notice the position of the keys and slider. Pushing the slider too far will cause the keys to fly out, so be extra careful.
Step 8:Install Upper Geartrain (Torque Fasteners)
Now that the counter gear has been placed back in the case, we are ready to install the upper geartrain. I tend to favor gluing the gasket on the main case to make it stay in place during assembly. This is my basic angle of approach to get the whole upper geartrain back in place. Once the extension is installed, I bolt it in place. Torque the rear bolts to 40 ft-lbs.
Step 9:Install Front Bearing (Torque Fasteners)
To install the front bearing, hold and pull the input shaft outward while using a punch to tap the bearing into place. Work the bearing down, side to side. Once seated, install both the outside locating snap ring and the inside rings with a snap-ring pliers. Install the front bearing retainer with a new seal and gasket. Torque the four front bearing retainer bolts to 20 ft-lbs.
Step 10: Install ShifterForks and Shafts (Important!)
The 1-2 shift fork must be correctly positioned on the 1-2 slider. Install both forks, along with their corresponding shifter shafts, in the case when working with a combstyle cover. Use plenty of assembly gel to hold all the parts in place.
Use plenty of gel or grease on the shifter shafts. Locate the shafts on the cover and wiggle it down into place. Be careful not to cut up the O-rings and do not force or hammer it!
Step 11: Install Side Cover Over Detent Combs (Torque Fasteners)
The cover drops down and stops when the ends of the forks butt up against the detent combs. You usually have about a 3/8-inch gap at this point. Use a small screwdriver to push the comb ends over the forks, which allows the cover to drop into place. If this were a ball-style detent cover, you would simply install the shift forks and drop the cover assembly down onto the forks. Torque the cover bolts to 20 ft-lbs.
Step 12: Install Reverse Detent Ball and Parts
Install the reverse detent ball, spring, detent end cap, and the reverse light switch. The factory had little paper gaskets for these parts, which are not easily available. The 51813 gasket eliminator works well.
Step 13: Install Speedometer Gear
This is a 32-tooth speedometer gear. Rotate the 32-38 index mark until it aligns with the mark on the tail. Then install the hold-down and bolt.
The A833 has been completely rebuilt. Typically, Dextron II or Dextron III lubricant is used in the A833. That’s what was in this box and that is what I will use to refill it.
Written by Paul Cangialosi and Posted with Permission of CarTechBooks