C1 Driveline vibration revisited

[Ed Jennings]

I posted a thread on this subject a few days ago, and got several responses to the effect that I needed to shim the transmission down to reduce the angle of the u joint. Today I installed four 1/4" shims between the frame and the transmission mount and then test drove the car. There was a big difference. The vibration can only be detected in a narrow speed range around 30 MPH. Above 35-40 it disappears altogether. I'm guessing a bit at the actual speed because my speedometer reads high. I need to change the gear, but that hasn't worked it's way up to the top of the pile yet. The remaining vibration seems to be most noticeable when accelerating. Question: Should I attempt to shim the transmission down another 1/8 or 1/16?

Any additional advise would be appreciated.

[John H.]

Re: C1 Driveline vibration revisited

Ed -

Have you checked your front motormounts and your trans mount? Generally when a driveline vibration is only apparent under acceleration load, it's traceable to a problem with mounts grounding out due to rubber wear or deterioration.

John

[Ed Jennings]

Re: C1 Driveline vibration revisited

John, I've had the mounts out and they APPEAR to be ok. Good and tight on both ends. I'm probably going to have to pull the trans and go through it. I suspect I've got some wear in the output shaft bearings. Got some lube leaks that need attention anyway. I may try to nurse it through this season though.It's apparently been like this for quite a while. I don't thik another few months wil hurt it. If it gets worse, I'll bite the bullet and pull it.