VCU Failure and Excessive RTV Leads to Bearing Failure

VCU Failure and Excessive RTV Leads to Bearing Failure

Transmission Sealant

Getrag used an anaerobic sealant in their 3000GT and Dodge Stealth Transmission builds. An equivalent that can be used today is Permatex 51813.

Many of the transmissions we rebuild here have been rebuilt in the past at least once and its very common to see black, grey, or orange RTV sealant used instead of the anaerobic sealant.

The RTV sealant will seal up the transmission case, but there are some disadvantages. The #1 problem is excess RTV sealant will circulate through the transmission, clogging up synchros, hub/slider splines, and needle bearing oiling holes like the one below.

The oiling groove hole is completely blocked in this transmission. This will lead to the failure of the gear’s needle bearing.
This is the hole unclogged. You can also observe orange RTV on the needle bearing that has migrated from the sealant used on the case.

Anaerobic Sealant Advantage

The biggest advantage to the anaerobic sealant is that it will not cure in the presence of oxygen, so it only hardens in between the metal surfaces. Any excess sealant will be harmlessly carried away on your first trans fluid change, rather than hardening and clogging up the transmission.

VCU Failure

The viscous coupling unit in the 3000GT and Dodge Stealth AWD cars is designed to limit the amount of slip between each axle set. It is a limited slip unit for the center differential. When they get old, or are abused by running with a broken output shaft, or towing with the car not on a flat bed they will leak out all of their viscous fluid. This fluid will often color the entire inside of the transmission black and contaminate everything in the trans. This is why its so important to clean every component and while you should not just replace parts that appear bad when taking the time to disassemble one of these transmissions.

In this picture you can see VCU good was clogging up the sleeve/slider splines.
 This VCU goo came out of the center of a counter shaft and illustrates how a VCU failure necessitates a full rebuild.

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