Nasty Vibration

[Mike Voth]

The "lug" was welded just past center, more towards the outside of the hat than the inside. There was a small one on the opposite side that was cut off to balance properly. Something doesn't add up...without breaking a finger, etc., how can a pressure plate be that far out of balance?

The mainshaft appears straight, but we'll know later today for sure when we get it back from the machine shop.

[Adger Smith]

Mike,
It could have something in the clutch failing and the plate be way off center.
I'm not familar with your clutch, but the old Long style and Borg & Beck I used back in the 70's would shift the pressure plate off center if a stirup or a hat hold down bolt would/was failing.

Good Luck

[Jim B]

I really can't explain the driveshaft change and temporary vibration reduction having anything to do with what you have going on in the pressure plate but pay attention to Adger. If it's a failing eyebolt the plate will shift and cause what you found. (assuming the balance has changed) Definitely double check your finger height at whatever compressed thickness your disc is before reusing the pressure plate. I'm also assuming there is no centrifugal weight malfunction going on. Good luck....

[Casey Miles]

I went through a vibration problem with my car and it ended up being the universals that the drive shaft company installed were .040 too short in the sleeve that they sat in. Another words, if you messure the end to end of the universal, they might not fit exactly the way they are supposed to. I found it by going under the car, when getting myself back out, I grabbed the drive shaft and it went clunk. It was only .030 to .040 too short, but I went crazy looking for the vibration. The manufacterer was I believe Splicer and they were the 1350 solid joints.

Casey Miles
248H

[Jeff Lee]

I have heard of clutch surfaces being machined (improperly) at an angle and accounting for such out of balance numbers as you are reporting. You won't be able to see the problem either. It will also make your runs horribly inconsistent and a vibration. Measure all of your friction surfaces from side to side across 4 corners.
If you find your pilot bearing (I hope you use a bearing and not a bushing) is bad, I wouldn't jump to the conclusion that was the initial problem until I measured the clutch parts.
While on the subject, I've also heard of heat shields being ground but the back side remains warped from excessive heat. That will also cause problems because the friction side has inconsistent depths of material.
And while your at it, make sure your bellhousing to trans mounting surface is still parallel. Years of bolting down a trans can take it's toll on this. And re-dial indicate the run out of everything too.

[Jeff Lee]

Originally Posted by Mike Voth

The Monte has developed a very bad vibration in high gear. Changed driveshafts and the problem seemed to lessen temporarily, but it's back as bad as before. The driveshaft is straight. Dad can barely hold the shifter back in 4th as he crosses the finish line. We are taking the tranny apart to see if the mainshaft is bent or ???. Can a ring gear be out of balance? We are sending the clutch and disk away to get balanced. Axles ???.

Any help would be appreciated as we're really scratching our heads on this one.

Many thanks in advance!!

I bought an aluminum driveshaft with the trans yoke still attached and put it in my car. It came out of another Jerico equipped AMX and we both had Dana 60 rears so I figured it would be an easy swap.
The new shaft / trans yoke did not engage as far as my old driveshaft. I thought it wasn't a big deal, maybe 1/4" shorter than before.
That thing shook the car so bad when I pulled it out of my driveway I couldn't believe it. Then I tried to load the car on the trailer. I never got above 5 MPH and it sounded like the car was going to fall apart. I changed back to the MW CM driveshaft in the street as I didn't want to put it in gear and move it again. Took care of the problem.
Something to think about...

[Jeff Stout]

Had a rifle drilled axle bent in housing. It was twisted and curved half way down axle. Low speed was noticable but top end it was bad.

[Mike Voth]

Two things:

1. Found out that the pressure plate was balanced without the disc in place. In doing so, the floater can move around causing this inbalance and also, adding weight to the pressure plate where it was added is a no-no. Clutch is going back to Hyatt to get fixed.

2. Took the rears to get high speed balanced, and the results were not good! We have egg shaped slicks that were produced in 2001, and we just bought them!!

As John Force would say..."Bottom line is..." we may not have found the problem yet. The search continues...

[Dyno]

Where did you buy "new" 9 year old tires? Send them back. Dyno

[Jeff Lee]

Shelf life on slicks is 3 years...may vary by manufacturer but that's approximate. I always make sure I'm getting the freshest sets available.
Find out what your mfg says about shelf life and demand a new set from the vendor you bought them from.

And do get that clutch fixed by Hyatt!