Mopar A-833 Transmission: An In-Depth Guide

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With the development of new and more powerful engines in the early 60s, Chrysler knew it needed a four-speed transmission to carry the load.

The Chrysler A-833 was a four-speed manual transmission manufactured by New Process Gear for 1964 - ‘86 Mopar vehicles. The four-speed found its way into many Max Wedge, 440, and Hemi-powered muscle cars. An overdrive variant was developed in 1975 and used in many Mopar cars, trucks, and vans.

Think of the early muscle car era during the sixties, and you might think of the 426 Hemi, the 440 Six-Pack, or even the Max Wedge Ramcharger 413. Still, the truth is that none of those beautiful engines would have obtained the claim to fame without a quality transmission backing them up. When Chrysler needed a new 4-speed manual to handle to load levels of these new high-performance engines, it turned to New Process Gear for answers. Over the next decade and a half, Mopar would see the A-833 take off and be used on the track and on the street in almost every vehicle they made. Let’s look at the Mopar A-833 to see what made this transmission so reliable and famous for many years.

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The Factors That Prompted The A-833 Transmission

With the rising popularity of motorsports in the early sixties and the growing demand for high-output engines, Mopar sought to capitalize on the trend by competing with Ford and GM to develop ever-increasingly powerful engines. The success of Chevy’s 409 and Pontiac’s 421 forced Chrysler to follow suit by introducing its Max Performance Wedge and a revamped Hemi engine.

Chrysler’s concern centered around the fact that the three-speed transmission (A745 and T85) was not strong enough to handle the increased torque these new engines could produce. To rectify this problem, Mopar attempted to use the Borg Warner T-10, tacking it onto the 413 Ramcharger Max Wedge, but shortly after doing so, they discovered that the new four-speed was inadequate. Left with a host of high-performance engines but without reliable four-speed manual transmission to support it, they turned to New Process. After a short time, the Chrysler A-833 was born. It was first used on various Mopar production vehicles in 1964. Later, the A833 would be found in most of the A and B body Mopar lineup, not just to back up V8s. (The transmission was also valuable in supporting the Slant Sixes in the mid-’60s and again with the ‘75 overdrive unit). In addition, the A833 found its way into plenty of use in drag racing, including the 1970 Ronnie Sox’s Plymouth Hemi ‘Cuda, which might be one reason he was nicknamed “Mr. Four-Speed.”

The Features Of The A-833 Transmission

The A833 was a heavy-duty transmission with a cast iron main case (until 1975, when it made the switch to aluminum), and it was designed to provide durability and strength. While the TorqueFlite was wrapped in an aluminum casing, NP built the A-833 with just as strong of internals. The transmission used wider and taller gears with nearly 3.5 inches of length between the input shaft and the cluster gear. The length was the largest Mopar had ever attempted to use. Still, the increased distance allowed for more power for low wheel speed, which aided in acceleration and made the A833 perfect for cars that needed quick take-offs (whether racing from a red light or drag racing on the track).

For the first year of production, the A-833 had a ball and trunion setup to connect with the driveshaft, but this was modified post-1965 to the more efficient spline output that accepted a slip-yoke. The transmission used various sizes of tail shafts depending on the type of car it was needed on. The smaller A-body passenger cars utilized a shorter version (23.1875) with the shifter mounted on the tail shaft. From 1966, the short tail shafts employed a 26-spline input shaft with a slip yoke (the A904 automatic had the exact spline count). More extended tail shaft versions of the A833 utilized 27-inch with 30-spline input shafts, matching the A727 automatic TorqueFlite.

The A-833 used two different kinds of access covers during its production. Earlier models built before 1970 had a ball and detent shift linkage cover, while the post-'71 models had an interlock shift linkage cover. Casting numbers were stamped on the extension housing or, on some models, placed on the front. During the 1968 production, the identification numbers were stamped on a raised pad on the transmission's passenger side.

The A833 was manufactured with multiple gearing options and spline counts. The 23-spline input shaft was suited for early Barracuda (‘64-’66), with a 3.09:1 first gear, and the A-body models (‘67 - ‘79), B-body and full-sized models (‘64 - ‘70) and few ‘66 426 Hemis used a 2.66:1. The A833 transmission used on ‘66 - ‘79 Hemi V8, 440 V8s had a 2.65:1 first gear, while the ‘70 B and E Body cars with the 340, 400, and 440 had a 2.44:1 first, both using 18-inch spline input shafts.

In 1966, several changes were made, not the worst of which was the Hurst shifter being replaced by a cheaper, less sturdy hollow shaft. Most reviewers hated the change, and Mopar owners complained about breakage, so Mopar brought it back soon after they had changed it. In addition, the transmission was made more precise in calibration with larger pinions. A gearset was added to the Street Hemi models, with new angles for the gear teeth, a thicker input shaft, and a larger bearing and retainer.

For 1967, Mopar eliminated the brass stop rings, to keep the amount of breakage that seemed to be occurring during hard shifts. (Imagine that, someone shifting hard in a 426 Hemi). The changes made the transmission smooth out the shifts and enhanced the internal components' strength.

Another change occurred in 1970 when somebody on Mopar suggested that they put a “pistol-style grip” handle that was standard on all E-body 4-speeds. The faux wood-grained strips were bolted on either side of the primary shift stock, with a top cap emblazoned with the shift pattern keeping it all together. The pistol grip is highly sought after by restorers and is extremely hard to find, although there are lots of aftermarket substitutes fashioned to resemble them. Also, in 1970, the E-body AARs and the T/A models were given a new 2.47-low close-ratio gearset (which would later become standard across much of the Mopar lineup)

A significant change occurred in 1971 when the transmission received a revamp of the side cover and interlock mechanism. New steel interlock levers replaced the old ball and pin type. The switch required new shifting forks, now made of steel rather than brass.

The most significant change to the Mopar A833 transmission occurred in 1975 when it received an aluminum case and added an overdrive gear (the third gear ratio was reduced to .73:1 so that it could be used as an overdrive, and the fourth gear became the new third gear). The changes increased the A833’s usage, as fuel economy became a concern for the buying public (having just gone through an oil embargo).

For the next few years (until 1986), Mopar used the transmission over a broad section of its cars and for Dodge trucks and both Dodge/Plymouth cars and vans. These vehicles had a 23-spline input and a 3.09:1 first gear. The A833 would continue to be used until 1986 when Mopar retired the transmission.

Chevrolet used the factory overdrive transmission in ‘81 - ‘86 as an option for their Suburban, two-wheel, and four-wheel drive trucks. GM eventually replaced the A-833 with an SM465, which was more equipped for use in light-duty truck platforms.

What Should Be Considered If Rebuilding An A833?

There are several things to know if you decide to rebuild an A833. Since the automatic transmission was used in various cars with different input shafts and spline counts, it is best to know exactly what kind of A833 you have. Double-check the transmission id numbers to ensure you have the right internals that go with the transmission. Another suggestion is replacing the snap ring and bearing retainer because they are thin and tend to get damaged when removed.

The A-833 Mopar transmissions that were built pre-1975 (cast iron case) are generally the units that are the most sought after and considered the most dependable. Many aluminum-cased transmissions with overdrive are not built for high-performance engines like the 440 or 426 Hemi.