91 T/A, 305, TPI: I feel a strong vibration coming thru the shifter handle when RPM's reach 3,000 rpm and higher. Doesn't matter which gear and is not present if out of gear and just reving engine over 3k. Any ideas would be appreciated.

I know there has got to be some good ideas out here. After re-reading all the posts I'm thinking it may be related to:
1. Pilot Bearing?
2. Transmission mount?
3. Drive shaft?
4. U-Joints?

Since vibrations start at 3,000 rpm regardless of which gear, does this mean the problem has to be between the flywheel and 1st gear ... as these are the only things that would be turning at the same rpm as engine?

[This message has been edited by Jcpstrat (edited September 19, 2001).]

 

Now this is getting weird! I replaced rear shocks tonight and when I drove it the vibration has moved from 3,000 rpm to 3,500. I thought I was getting somewhere with thinking it had to be near the flywheel or 1st gear to always follow engine rpm but this is starting to mess with my mind.

Come on people ... I need brain power and/or experience! Not to mention that its lonely just talking to yourself!

[This message has been edited by Jcpstrat (edited October 01, 2001).]

 

I agree with you about the vibrations being only a function of the motor, flywheel, or clutch. Does it vibrate when it is in neutral? If so, then it has to something before the transmission. Actually, I have this same problem with my car, although my vibration may not be as bad. Unfortunalely I haven't fixed it yet. But I suspect that it is either the pilot bearing or the flywheel. If the pilot bearing is worn out, then the transmission shaft and clutch can become eccentric with the centerline and cause a vibration. The flywheel can also be out of balance or warped. If the flywheel is worn a lot or has been cut, there is a chance that it is warped. I believe that this is the problem with my car. I've had my flywheel cut twice and it tends to chatter when I heat it up. Hope this helps
-Chris

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1990 Formula WS6 - 305 - T5
14.3 @ 96.5 mph
MSD 6AL
Strut tower brace
Subframe connectors
MAC headers
Underpulleys

 

Chris90Formula ... thanks for the question. I checked it in neutral with clutch out and in gear with clutch depressed and there seems to be more vibration neutal and clutch out. I would think that this would lean more to the theory of pilot bearing since the clutch would also be spinning and possibly mis-aligned slightly. Maybe the new shocks just had a damping effect. I also have been noticing a small amount of clutch chatter after being driven ... usually not there on cold starts. Anyone else have some thoughts on this?