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Argess 10-20-2011 07:31 PM

Transmission Mount / Driveshaft Angle Question
I changed my transmission mount a while back in an effort to cure some clutch chatter. Didn't help very much, but I finally traced the problem down to air in the hydraulics due to a leaky slave cylinder. Replaced the slave cylinder and chatter went away.

But then I noticed a new problem. Some tapping or knocking while engaging the clutch. That turned out to be the clutch fork hitting the inside of the transmission tunnel. Turned out this was caused by the new transmission mount which was about 1/4" higher than original.

Re-installed the old mount and the tapping/knocking went away, but now I have a clunk when I shift. Happens almost 1/2 the time, and only when engaging 1st and a little bit when shifting from 1st to 2nd.

The old transmission mount was a bit soft from age and oil, and I know it will flex a bit more than the new one.

The puzzle is, whether the clunk is from the old soft mount causing things to move about, or is it from the old mount being 1/4" shorter than the new one and that makes the transmission center-line and differential centerline no longer parallel. Or maybe both?

So I think I'm looking at either adjusting the pinion angle or trying to source a shorter and stiffer tranny mount such as a polyurethane one.

Any thoughts?

Further info:

1/ I'm using IRS with a rigid mounted diferential and a driveshaft not much longer than a tall-boy beer can. I can raise or lower the diff pinion angle a little bit if required.

2/ Old mount is a GM part which is no longer available. New mount was Auto-Parts store after-market replacement.

3/ I'll know more once I get hold of some sort of bubble protractor and can make some measurements.

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