to the lack of roller bearings and thrust washers.
Malfunctions and Fixes
The A-833’s most popular claim to fame, is that it rarely broke. Most often, these transmissions needed a rebuild because they were worn out. The strength factor causes you to see an A-833 modified to fit into many GM cars. Using an adapter plate and shortening the input shaft tip accomplishes this. One must also decrease the diameter of the tip to 5/8 inch.
This plate manufactured by Passon Performance adapts the A-833 to the standard Muncie bellhousing. The four threaded holes are where the A-833 attaches to the mount plate. The four larger holes that are generally equidistant from each other are where the adapter plate is bolted to the GM bellhousing.
The upper input shaft pictured is modified for use with a 1-inch-thick adapter plate. The typical GM pilot tip diameter is 5/8 inch. The lower input shaft is a stock untouched Chrysler input shaft. Notice how much longer the pilot tip is. Also, the diameter is 3/4 inch.
Popping Out of Gear
The most common misdiagnosis is how to fix an A-833 that is popping out of gear. When we get a call that this is happening, I will ask some specific questions and the customer will often say, “I just had synchros put in, and that didn’t fix it!” Replacing the brass synchronizer rings will not fix a pop-out condition. Synchronizer rings get the transmission into gear. They do nothing to keep it in gear.
Popping out of gear can happen for a myriad of reasons:
This is an example of how an operating lever in the shifter mechanism itself can become worn, causing the transmission to pop out of gear. The lever on the left has the correct diameter hole. The lever on the right exhibits significant wear. This allows the arm to “run out of travel” before moving the shift fork the correct distance.
• A slider that is not fully engaging onto the synchronizer teeth of the gear. This can happen due to a worn shift fork; the forks are in constant contact with the slider and can become worn in the area of contact.
• A bad rear bearing or broken snap ring groove in the bearing pocket.
• A missing snap ring. We have seen this after some inexperienced people have been in an A-833. The reason that this is important is because, by its design (helical drive tooth), there is forward and backward thrust on the bearings whether accelerating or decelerating. When a rear bearing is allowed to move forward and backward (for whatever reason), the entire mainshaft moves. This will affect staying in gear because the sliders (which are attached to the stationary housing via the forks) will try to stay stationary while the mainshaft moves independently.
• The drive-side of the synchronizer teeth is worn. This can cause pop out under power.
• Misalignment of the bellhousing.
• Worn synchronizer teeth. This is by far the most common thing that causes a transmission to pop out of gear. This can happen in a couple different ways. As a synchronizer ring becomes worn and eventually fails, a grind occurs during shifting into that particular gear. This grind is the result of the splines on the slider being at a different speed than the gear. When this grind occurs, it wears the synchronizer teeth. As the teeth recede back and the slider wears, they will no longer stay in gear when not under power. Another action that will cause worn synchronizer teeth is sloppy driving. This is when the driver drags the shifter out of gear instead of pushing the clutch in and shifting. All of the weight of the car is stacked up against the side of the synchronizer tooth of whatever gear the transmission is in. When the slider is dragged off the gear, it wears the side of the synchronizer teeth. After thousands of times, the teeth will show wear and the unit will pop out.
• The gear selector shafts are worn. This can cause a pop-out condition because the shifter is completing the allowable travel and the slider is not moving far enough because of the worn shaft.
• A worn or misadjusted shifter. This will be covered in the shifter section, later.
This gear shows excessive wear on the synchronizer teeth. Note how they have receded. If installed into a transmission, this gear will almost definitely pop out of gear when the driver lets up the accelerator. Once a gear is this worn, it must be discarded, unfortunately, because there is no fix for these.
Grinding During Shift
When a transmission grinds during a shift, it means that the brass synchronizer rings are not functioning correctly. Synchronizer rings can malfunction for reasons ranging from a broken or spread synchronizer ring to a bad gear cone and many things in between. Incorrect clutch adjustments can also have an adverse effect on the function of the rings. If the clutch is not completely releasing, the engine is still transmitting power through the transmission. This will require the synchronizer rings to undergo extra abuse to get the gear speed matched to the slider. After extended periods like this, they will fail prematurely. The harder a transmission is driven, the more wear is to be expected on the synchronizer rings.
A grind typically shows up in reverse initially if there is a clutch problem and you are not getting complete release. Since reverse is the only gear that is unsynchronized, the geartrain must be stopped to engage it. The old trick back in the day was to put it in first gear to briefly stop the geartrain and then quickly put it into reverse before the gears start spinning inside the case.
Notice that the stretched, worn synchronizer ring (top) is darker in color than the new ring (bottom). Also notice the fine grooves that are in each ring. The worn ring shows much more space between the grooves. Essentially, the material between the grooves is worn and it makes the grooves shallow, appearing as if there is more material between them.
The marks on the synchronizer ring to the left indicate that it was bottoming out on the face of the gear instead of applying braking pressure to the gear itself. The ring to the right is a new, unused ring. Notice the lack of marks.
The fitment of a brass synchronizer ring on the cone of the gear is shown here. Notice that there is almost no clearance between the ring and the gear. This ring is both worn and stretched. When pressure is applied to the brass ring via the synchronizer strut keys, the ring will bottom out before the inner part of the brass ring applies braking to the cone of the gear. The end result will be a grind when shifting into that gear.
Bad Bearings
It helps if you can properly diagnose the problem with the transmission before tearing into it. Since some parts for the A-833 are difficult to obtain, it may take some time to acquire them. Typically, a bad bearing will make a growling sound. Usually, there are two main bearings, with the exception of the 1964–1965 flange-type output. They have a bearing at the extreme end of the tailhousing as well. A bad input shaft bearing will make noise with the unit sitting in neutral or in all the gears.
