Chrysler A-833 Transmissions: How to Rebuild and Modify

INTRODUCTION

Chrysler’s A-833 4-speed transmission was manufactured from 1964 until 1986. It went through several design changes and upgrades throughout its extensive manufacturing run. A mid-1980s version was even offered in both two-wheel drive and four-wheel drive. This GM iteration was commonly known as the MY6; Chrysler never offered it as a four-wheel drive transmission. I will focus on the original Chrysler version of this transmission. New Process Gear in Syracuse, New York, (which Chrysler had purchased in 1934) manufactured all of the A-833 manual transmissions that Chrysler offered.

The A-833 was built in two versions: standard duty and heavy duty. The standard-duty unit used a 1-inch-diameter 23-spline input shaft. The heavy-duty version used a 1 -inch-diameter 18-spline input shaft. Along with this larger-diameter input shaft, the internal speed gears (mainshaft) used bushed gear bores to prevent seizure to the mainshaft. This design worked well; I have never had an 18-spline gear seized to the mainshaft. However, I have had a number of 23-spline transmissions with this issue through the years.

Chapter 1 focuses on the different component and design changes throughout the production run of the A-833 to provide a detailed explanation of how the A-833 evolved. It also describes the different gearsets, synchronizer designs, component changes, and how the unit has improved through the years.

Chapter 2 outlines the basics of function in the A-833, some of which are exclusive to this gearbox design. It explains how the external and internal parts work together to transmit power through the unit. It also identifies the most common ailments of the A-833 and provides the common remedies for these problems.

I describe how to identify the A-833 transmission in Chapter 3. This chapter offers complete casting number information for all main components and lists the vehicles that these different components fit. Also included is date code information for the different components. In addition, it provides a detailed description of the various fasteners that were used during the production of the A-833 transmission. Finally, the VIN pad stampings are explained.

In Chapter 4, I dig into the actual rebuilding of the A-833 transmission. I begin with tips on creating a clean, efficient work area and explain what tools are needed to accomplish the actual rebuild job. Each section of the transmission is detailed: disassembly, cleaning, inspection, and reconditioning. The final section is reassembly.

I delve into different performance upgrades that are available for the A-833 transmission in Chapter 5. These range from lightweight housing parts to gears of different materials and different gear ratios. I also explain different synchronizer designs for improved performance.

Chapter 6 breaks down all aspects of the shifters that were used on the A-833 from the beginning until the end of production. It describes the various shifter handles, the vehicles in which they were used, and the years. It also covers the different shifter linkage rods and the shifter mount pads, providing the specifics of what types of vehicles and years they fit.

Finally, Chapter 7 identifies the bellhousings that were used from 1964 through the end of production. It provides the details for each bellhousing regarding which engine and vehicle it fits. In addition, it separates small-block from big-block. It also covers the different materials from which these bellhousings were constructed.

Writing this has been quite a journey. It is, without a doubt, the most difficult thing that I have ever undertaken on a professional level and I have learned an incredible amount. One thing for sure is that when you think that you know everything about a subject, you don’t! I hope that the readers use this book to keep these transmissions working properly and thereby continue the hobby of restoring the old vehicles so that they can be driven and enjoyed. You’ll feel a tremendous sense of pride when you grab second gear knowing that you brought that A-833 back to life with your own two hands!

CHAPTER 1

HISTORY OF THE A-833

The years 1962 and 1963 marked the beginning of serious horsepower packed into a plain package at Chrysler Corporation. With the advent of the 413 and 426 Max Wedge and later, the 426 Hemi, Chrysler found itself behind the eight ball when it came to manual transmissions. Particularly when it came to 4-speed transmissions. Chrysler typically used the BorgWarner T-85 3-speed transmission. However, most of its dragstrip competitors had manual transmissions with four forward speeds. This put Chrysler at a disadvantage.

At the time, the current offering in a 4-speed was the BorgWarner T-10 transmission. This unit proved to be a disaster, as it could not take the horsepower that the 413 and 426 Max Wedge engines were creating. With the new 426-ci Hemi on the horizon, Chrysler engineers knew that they needed to create a stronger 4-speed transmission. The engineers at New Process, part of the driveline division of the Chrysler Corporation in Syracuse, New York, put their heads together. In 1964, they released the A-833 4-speed manual transmission.

This transmission was created out of necessity due to the weakness of the BorgWarner T-10, and it filled the void perfectly. It was arguably the strongest passenger car manual transmission ever made. This strength is due, in large part, to the 3.5 inch center distance between the input shaft and the cluster gear. It was initially designed with a 23-spline input shaft, as well as a cast-iron main case, tailhousing, and sidecover.

The A-833 4-speed transmission went through many design changes and enhancements throughout its production run from 1964 until 1986. Without a doubt, the A-833 is the most varied design transmission during the muscle car era. Just one example of this is the entirely different front bearing retainers that were used. But there were many other changes as well.

One of the many design changes of the A-833 was the front bearing retainers used. Six common bearing retainers that are used on the A-833 transmission (shown here) were made of cast iron and used a seal that was pressed into the retainer itself. The retainer used a paper gasket to seal against the case. The four bolts used to fasten the retainer must have sealing compound applied to their threads, as the holes extend into the interior of the main case. The only one not pictured is a 1975-only that used a small 307 bearing and had the large 5.125 inch OD.

A-833 Design and Component Changes

The A-833 went through a few platform changes throughout the years. Along with these external changes, there were a myriad of internal ones. They will be explored in the following pages.

1964–1965

The initial A-833 configuration had a 23-spline input shaft and a splined output shaft with a threaded section at the end. The flange slid onto the splines and was retained by a special serrated locking nut and washer. A flange connected to a driveshaft equipped with a booted universal joint, called a ball and trunnion, via four 3/8 -24 studs and a special tall corresponding nut. No washer was used. The A-Body flange was smaller than the B- and C-Body versions.

All three 1964–1965 tailhousings are displayed here. The top is for an A-Body, the middle is for a C-Body, and the bottom is for a B-Body. Notice the speedometer gear keeper bolt location at four o’clock on the B-Body versus one o’clock on the C-Body. The transmission mount flange is also wider on the bottom of the housing on the C-Body.

There were two versions of this configuration. The A-Body had a tailhousing length of 10½ inches less the flange. The B-Body and C-Body version had a length of 16¼ inches less the flange.

There were also different first-gear ratios for each of these configurations. The A-Body had a 3.09, and the B- and C-Bodies had 2.66. The 1964 and some 1965 production units used an oil slinger between the input shaft drive teeth and the front bearing. The initial shift fork design (in 1964) was a very small paddle-type 1-2 made of a brass alloy and a steel 3-4 fork.

These forks were used in 1964. The top fork is the small paddle-type 1-2 fork that caused problems with power shifting because of unequal pressure on the slider. The lower 3-4 fork was steel and worked well.

This shift fork design proved to be an issue for power shifting, as it did not spread the force out over the circumference of the slider, loading one side of it. The fork was redesigned for 1965, and this fixed the problem. The 3-4 fork was also switched from steel to a brass alloy that year. The 18-spline input shaft also was introduced in late 1965.

The 23-spline front bearing retainer had a casting number of C-94796. This was the only retainer used on 23-spline units until 1967. The B- and C-Body units used a 307 bearing in the front and mid location. A 206 bearing supported the rear of the output shaft very solidly. This design was favored for competition in NASCAR, even after the slip yoke output shaft replaced it in normal production.

As you can see, the improved 1-2 fork design for 1965 (top) has a wider span to equalize pressure to move the slider more evenly. The 3-4 fork (bottom) was changed to a brass alloy material that was consistent with the 1-2 fork. This was likely done in order to streamline manufacturing so that two different materials were not needed.

1966–1967

There were several changes for 1966. One was the elimination of the slinger on the input shaft. Another change was that the sidecover bores were a heavier casting with improved gusseting. These were initially a very thin casting in 1964 and 1965 and were prone to cracking. The input and main bearings stayed the same (307) size as the previous years.

The largest change was the output shaft design. It went to the much more common slip yoke type. This change occurred on the 727 Torque-Flite automatic transmissions in 1965. The slip yoke had splines at the rear end of the output shaft. This allowed a yoke attached to the driveshaft via a universal joint to slide on the shaft depending on driving conditions and suspension travel.

This photo shows the eight different A-833 shaft configurations throughout the entire production run. Unlike other auto manufacturers, the A-833 had many different configurations. The shafts from top to bottom are: 1. 1964–1965 B- and C-Body 1:1 final drive ball and trunnion type, 2. 1964–1965 A-Body 1:1 final drive ball and trunnion type, 3. 1966–1974 B- and E-Body 1:1 final drive 30-spline output, 4. 1966–mid-1967 A-Body 1:1 final drive 26-spline slip yoke type, 5. mid-1967–1975 A-Body 1:1 final drive 30-spline output, 6. 1975–1986 truck overdrive 30-spline output, 7. 1977 F-Body overdrive 26-spline slip yoke output, and 8. A- and F-Body overdrive 30-spline slip yoke type.

This design did not allow for a support bearing as the previous trunnion design had. A bushing was now installed in the tailhousing. This slip yoke–type output shaft was available in two different configurations, a 26-spline design for the 1966 and early 1967 A-Body and a 30-spline for the later A-, B-, and C-Body cars.

In 1966, the 3.09 first-gear ratio was discontinued. This would be shelved until the mid 1970s. It was the first year of regular production of the 18-spline A-833 as well. This was standard equipment in vehicles equipped with the 440 and 426 Hemi engines. This is how the 18-spline A-833 became known as a hemi 4-speed. The 426 Wedge (Street Wedge for 1964–1965 and Max Wedge for 1964) were not equipped with the 18-spline A-833.

The early speedometer gear on cable design was also ditched for 1966. In this new design, the cable and driven speedometer gear were independent of each other. This change allowed much more precise speedometer calibration as well as the ability to produce and supply fewer parts by sharing the design with the automatic.

1968–1969

The first major redesign regarding internals of the A-833 occurred in 1968. At this time, the synchronizer assemblies were redesigned. The neutral detent in the slider was much wider and deeper than before. In addition, the strut keys were redesigned to match the slider detent. They were shortened from 1.175 inches long to .950 inch long. The keys stayed the same width at .216 inch wide. The change in strut key design required a synchronizer hub design change as well. The slots where the keys ride needed to be machined deeper to compensate for the taller strut key. Even with the changes, the brass synchronizer stop rings stayed the same.

Another significant change was the bearing size increase on the 18-spline A-833. This was increased to a 308 series bearing. New Process used MRC as the OEM bearing supplier throughout the run of this transmission. The upgrade to the 308 series bearing was a simple design change. The standard 308 bearing had a larger internal bore than the 307 bearing, and it was actually slightly thinner at .795 inch thick. The 307 that was being used in the A-833 was .825 inch thick. The issue was that everything was already designed for a specific bore diameter and bearing thickness. Therefore, the 308 bearing instantly became an application-specific bearing design. This spelled availability troubles several years ago when SKF Corporation bought the MRC Corporation. Ultimately, the 308 was dropped from production. Several aftermarket offshore vendors picked up production. However, there have been quality issues with some of these regarding size tolerances.

This shows the 307 bearing (top left), 308 bearing (bottom left), 206 bearing (top right), and output shaft bushing (bottom right).

Bearing retainers also changed in 1968. Until that year, all bellhousings had a register hole of 4.354 inches. Beginning in 1968, all big-block bellhousings received a register diameter increase to 4.805 inches. This required casting of a new bearing retainer. The new bearing retainer still had a 3.70-inch bolt circle, but it now had an outside diameter of 4.807 inches. This new bearing retainer was used in 1968 and 1969 on big-block 23-spline A-833 units because they still had the 307 bearing.

The 18-spline version got a new retainer as well due to the new 308 bearing. The bolt circle was increased to 4.16 inches.

The last noteworthy change for 1968 was the introduction of the vehicle identification number (VIN) to the transmission case. This information was stamped on pads and began showing up as a rough casting on the passenger’s side of the main case toward the front about one-third up from the bottom in mid-1967. However, they were not machined flat or stamped until 1968. There were two different size pads. The early one was 7/8 inch tall and about 2¼ inches long. Beginning in 1969, the pad length was increased to 3 inches long.

Take note that only transmission assembly information is present. This is the