T56 shifter seal correct fit

[CarlC]

Like many others, the Magnum shifter started to leak after a few months of use. It was the seal as shown above tearing at the shaft interface.

The seal is not replaceable. Tremec sent a new shifter, and after inspection, the seal is stretched too far. The high stress in the seal caused premature failure once exposed to heat and oil. This same type of seal failure also occurred on another aftermarket shifter that also had too much seal stretch. The seal on that shifter was much smaller, hence making the problem worse. The Tremec seal is far superior, but with an excessive interference fit on the seal.

The fix was to machine the groove where the seal seats to a smaller diameter. It's been over a year so far with, visually, good results. There is no oil on the top or around the top boot, whereas before it was making a big mess.