This transmission case is from a 1970 vehicle. Note the evenly spaced and straight VIN stamped on the case. By this time (actually 1969), character sets were being used to make numbers easily readable. You will notice a different font than was used on either of the earlier VIN pads. This became the standard font used on all A-833 4-speeds built from 1969 forward.
This is a service replacement transmission. It has only the transmission assembly information on it with no larger VIN. It is obvious that it has not been tampered with.
The Plymouth A.A.R. `Cuda and the Dodge Challenger T/A were the first vehicles to receive the new 2.47:1 gearset.
In addition to gear ratio change, the A-833 also received a synchronizer design update. One of the recurring issues with the previous two synchronizer designs (that used the exact same brass synchronizer stop rings) was cracks forming at the sharp corners of the slots in the rings. These slots were used to prevent the synchronizer ring from spinning by using a strut key that fit into the slot and kept it stationary. The new design used a tapered slot and included a brass lug around the outer circumference of the ring. This required a shorter strut key. Therefore, the key was shortened from .950 inch to .778 inch and increased in width from .216 inch to .382 inch.
All A-833 transmissions behind big-block engines received 308 front and rear bearings beginning in 1970. This required a new bearing retainer yet again. It shared all dimensions of the 1968 and newer 18-spline bearing retainer except the tube diameter, which was the same as the standard 23-spline.
1971–1974
This marked the first full year of production for the 2.47 (23-spline) and 2.44 (18-spline) gear ratios, interlocking lever sidecover, and lug-style synchronizers. Beginning with these gears, efforts were made to reduce costs. The gears were now single carburize–hardened instead of double carburize–hardened. In 1971, the “ball and detent” interlock mechanism was changed to the “double interlocking lever.”
The ball and detent design used a tube with a pair of spring-loaded balls with a dowel in between them. The shift forks are not part of this interlock mechanism. The interlocking lever design used two flat steel plates stacked and spring loaded, and the shift forks are part of this mechanism. Therefore, brass alloy was not up to the task, and forged steel forks were used to stand up to the repeated surface abuse of the levers. The idea behind both interlock types is so that the transmission cannot be put into two different forward gears at the same time. These interlock styles are the subject of some debate among enthusiasts. The double interlocking lever–type had better steel shift forks. However, it can be argued that the ball and detent type allowed easier and smoother shifting.
This shows the difference between the early and late sidecover interlock design. Top is later interlocking lever design; bottom is the earlier ball and detent design. It is generally accepted that the earlier type was better for racing. However, the later type used a more durable steel shift fork. Very often, people cut the pin off the later steel fork and use it in the earlier cover.
Note the additional pin on the stem of the 1-2 fork (top). This extends out farther than the earlier shift fork and becomes part of the interlock mechanism. This is, in part, why the material changed from brass to steel. The 3-4 fork is below the 1-2.
The last full year of production for the 18-spline transmission was 1971. With decreasing power outputs and the elimination of the 426 Hemi from the engine lineup, this heavy-duty unit was no longer needed. It continued to be installed in 440 and 440 six-pack cars into 1972; then it was phased out.
One final 1971 change was a provision for a switch for the 1971 sidecover that was activated when the transmission was put into fourth gear. This retarded the timing for decreased emissions. I am not aware of exactly which vehicles received this switch. Many of the interlocking lever–type sidecovers had this provision drilled and tapped with a plug instead of a switch.
The A-833 went on until 1974 largely unchanged in B- and E-Body cars. The long tailhousing configuration with a 1:1 final drive ratio ended in 1974 with the official end of the E-Body vehicle platform.
1975
The transition into the overdrive version of the A-833 began in 1975. This year was the end of the 1:1 final drive A-Body unit. This limited-production 1975 1:1 transmission was unique, as it still retained the small 307 front bearing. But it had a bearing retainer that was 5.125 inches in diameter to mate with the bellhousing for the overdrive version of the A-833. The bearing retainers eliminated the need for an adapter ring to use an overdrive bellhousing. However, they were very scarce. This was the only year (apart from 1964–1965) that the steep 3.09 first gear was used with a 1:1 final drive.
1976–1986
From 1976 until 1986, only the overdrive version of the A-833 was available. There were several changes during the last decade of production. There were two gearsets and output shaft designs in the F-body transmission. The F-Body version began with a cast-iron main case, tailhousing, and sidecover and a 30-spline output shaft. In 1977, an aluminum main case and tailhousing was used on the F-body cars, but it retained a cast-iron sidecover. The output shaft on some units was reduced to 26-spline, similar to the 1966–1967 A-Body 1:1 mainshaft.
The year 1986 heralded the end of the A-833 in passenger cars. The truck version began with a cast-iron main case, sidecover, and tailhousing. It evolved into an aluminum main case and sidecover with a cast-iron tailhousing. There were two different aluminum truck sidecovers. Their functions were identical, the casting just varied slightly.
In 1982, the synchronizer assembly was redesigned for the A-833. This redesigned assembly shares only strut keys and strut key springs with the mid-1970 version. The slider and hub are different and used the lug-style synchronizer rings. The sliders began a torque lock design that was similar to the design used in other 4-speed transmission models throughout the years.
In addition, the 1-2 shift fork design changed during this time. The 1-2 fork was enlarged to extend deeper into the slot in the 1-2 slider.
The difference between the early 1-2 interlocking lever shift fork and the late design is shown here. The early design fork (top) stamped F99385 was redesigned for the release of the overdrive version of the A-833 transmission. The design change is obvious, as there is more “meat” on the later design fork (bottom) stamped F-13636.
A-833 GEAR RATIOS
The A-833 has had a number of different gear ratios throughout its 23-year production run.
I would like to point out some notes regarding the gearsets mentioned below. First, all 18-spline speed gears have a dimpled oilite material bushing inside the bore of the gear. This is present in the first, second, and third gears. On 23-spline transmissions, the internal gear bores are not bushed. Both designs rarely have problems unless lube levels are allowed to drop too far.
In addition, a set of reverse idler teeth is present on all cluster gears. These always number 17. These are the same on all Chrysler A-833 cluster gears, whether in regular production or race gearsets. There is, however, a different reverse idler gear in some overdrive transmissions. These are