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. A bad mainshaft bearing will only make noise when the output shaft is turning (driving condition).
Whining Noise
A whine is usually caused by a problem with the gear teeth themselves. These can be caused by a lack of proper lubrication or improper bearings being used. Since the A-833 uses an application-specific 308 SG8 bearing, this tolerance is important. We have taken apart units in the past that have had 308 LOE bearings in them and have observed improper wear on the helical teeth because of it. These 308 LOE bearings are too thin. This moves the mainshaft forward and the input shaft back, which causes a misalignment with the cluster gear. This can create a whining noise and will eventually wear the gears irregularly. Mishandling or a catastrophic event, such as an internal part failure, cause dings that result in gear tooth irregularities. If the ding makes a high spot on the side of the gear tooth, it can cause a whine. If on the drive side, the whine will be noisy under power. If it’s on the coast side, it will be noisy when the driver lets off the accelerator pedal.
Visualize the face of this bearing as a clock; look at the eight o’clock position. You will notice that the cage that retains the correct spacing of the balls has broken. This will completely destroy the bearing in short order. As the cage breaks up, it will go through the transmission, likely causing significant damage. This bearing was caught before any of the cage broke free and destroyed the transmission.
If you focus on the inner race of this ball bearing, you will see significant brinelling. The surface hardening has left this area of the bearing. This will cause a growl and, eventually, the bearing will fail completely. This will get louder as the surface keeps getting worse and worse.
Banging Noise
This is typically an easy noise to diagnose. Very often, a jarring feeling in the vehicle is associated with the noise. It is caused by one or more teeth being knocked off either the mainshaft speed gear or the cluster gear. The transmission should not be driven when this happens. When pieces are floating around inside, they can get caught between other teeth and do further damage.
Typically, loss of teeth happens from overpowering a transmission. The usual weak point of the 23-spline A-833 is the input shaft. They will generally twist before something breaks inside. In order to take care of this issue, Chrysler engineers increased the input shaft diameter from 1 inch to 1
Many of the transmissions that end up in people’s hands now have led a tough life. The stress that this puts on the gears is incredibly high. Also, everyone did burnouts in third gear. This was to allow the most tire speed to heat the tires up faster. However, this is very hard on the transmission. We sell a 2.65 ratio third gear that is manufactured from 9310 alloy, which is notably stronger than the standard 8620 material assembly line gears. We have had good results with this improved material gear and have had almost no breakage.
Vibrations
Most times, vibrations are caused by something outside the transmission. These can range from driveshaft balance issues to universal joint wear issues to a bent driveshaft. Even axle bearings or tire/wheel issues can resonate up through the transmission and shifter.
The A-833 was designed to be used with a pilot bushing in the rear of the crankshaft. This supports the pilot tip of the input shaft to keep the mainshaft aligned. The driveshaft slip yoke keeps the mainshaft aligned as well. When these become worn, vibrations can develop.
In some instances, if a solid mount is used, it can transfer vibrations. There are 16 loose rollers present inside the bore of the input shaft. They support the front of the mainshaft. They do not have a super tight fit because assembly would be nearly impossible. This is an area of deflection under very high power loads. In addition, if a polyurethane mount with a high durometer is used, it can also transfer vibrations.
This gear shows just two teeth knocked off. This would still move the car, but every time the bad spot in the gear comes around and meshes with the cluster gear, you would get a bang and likely a loss of forward movement until the gear rolled past the bad spot. (Photo Courtesy Sawmill Garage-Sweden)