Car vibrates after new clutch???

[Guest 50silverstreak]

I have my '50 chieftain 6 in the shop to have the transmission serviced and clutch rebuilt. The car drives very smooth with the exception of a worn out clutch.

This is a Drivetrain shop that was rec and does work on older cars as well as bigger trucks. The transmission was in good shape except for some seals that were replaced. Bearings, gears, etc were all fine and the fluid looked good. They sent the stock clutch out to be rebuilt because they are so hard to find/purchase without sending in a core first. The fly wheel was turned, the pressure plate was balance, the new clutch installed,etc. (The rear axle seals were also replaced)

When I test drove the car there was an immediate and significant vibration when I pressed the accelerator while driving and while the clutch was pushed in while in neutral. The steering wheel and whole car seemed to shake which it had never done prior. They have taken the tranny back apart to check that the pressure plate plate was balanced, the flywheel was flat, etc. None of the obvious things were out of order.

Does anyone have any suggestions on what could be the problem? They were not able to balance the flywheel b/c the machine does not have a machine that would fit it. However, I was told that if it was not unbalanced before, turning it would not make it unbalanced? Was there possibly a counter weight used on these cars that could have been knocked off?

thanks, Christopher

[Guest kaycee]

Is the pressure plate assy. rebuilt too, or just the disc? Did they install a new throwout bearing? Does the clutch pedal vibrate with the car standing still in nuetral ( clutch pedal out)?

kaycee

[Guest 50silverstreak]

Kaycee,

Sorry for the delayed response to your question. I have been dealing with other issues...brakes, exhaust and intake manifolds, oh boy!

Yes the pressure plate assy is rebuilt too. new throw out bearing. yes the car vibrate while standing still while in nuetral, with the clutch out.

After the shop put it back together (and could not find anything out of place), the violent shaking was gone. What is left is just a slight vibration I feel at low speed up to about 35 mph. After that is gets less and less noticeable. The vibration is still there at rest with the clutch in or out, although far less than it was initially.

It was suggested to me by some of the "old guys" at the cruise ins that the rebuilt clutch media may not be soft enough and therefore not slipping properly on the flywheel causing it to "chatter slightly." I was told to drive it for a while and it might go away after 500-1000 miles.

It does not seem to have resolved or diminished but it is tolerable. It is not too noticeable with just a slight vibration notiecable at lower speeds. The issue I have is that it was not like this prior to the new clutch. Sometimes I think that I should just leave it and enjoy it with the slight imperfections.

Any thoughts with the new information?

Should I have the shop put a softer compund in that would allow that clutch to slip appropriately and to not chatter? (The shop will honor its work for a year) Do you think that the chatter would get progressively worse over time? Do you think this slight vibration will cause other issues long term with the flywheel, trans, bearings, etc? Or just enjoy it and make the changes the next time it needs a new clutch?

Thanks,

Christopher

[F&J]

It sounds like a balance problem, not a slippage problem.

If the shop is a good place, they would have replaced the pilot bushing in the end of the crankshaft and made sure it was the correct size with no slop. That slop can cause a vibration because the clutch disc would act like it is out of balance.

So if not that, then a minor imbalance can be helped or nearly eliminated by a painstaking test fitting of extra washers on one or two of the clutch mounting bolts. You need to start adding a washer, one at a time, and mark the spot where you had it. If it is worse, move the washer to the opposite side. Keep marking your changes, and you may get to the point of having two washers on one bolt, or a single washer on two adjacent bolts.

it's tedious work, starting and running the engine on each change, but might be worthwhile.

A slim chance, but are all the clutch bolts exactly the same? meaning maybe one or two bolts got replaced by longer/heavier bolts?

[Guest]

Did the shop index the driveshaft??

D.

[Guest 50silverstreak]

Not sure what you mean by "index" the drive shaft. Could you elaborate?

Also, what exactly does the pilot bushing do?

[Guest]

Before you remove a driveshaft from the rear end you always mark it at the third member so it goes back the same way . Sometimes if you don't do this (index it) you will get vibration because it would be 180 degrees off. Sometimes even wild vibration and this will cause worn out trans tail shaft seal, universal joints, pinion bearing wear, pinion seal leakage and if it's really bad a thrown driveshaft.

A pilot bushing in the end of the crankshaft guides and centers the mainshaft of the transmission/ or a transaxel to the flywheel of the engine when they are bolted together.