vibration

[devilfish]

I have changed the clutch on my 1991 vette. I also put new u-joints on my drive shatf. Now I have vibration at around 130 km/h and abow.
First I thougt My new clutch set-up could be out of balance. BUT I tried to disengage the clutch at 130km/h and I still get the vibrations. So that should leve it to the drive shaft, right? Must I rebalance the driveshaft when installing u-joints?
WHats your feedback?

Regards

 

[Ken]

When you changed your clutch assembly, did you surface the flywheel or anything? From what I understand, the dual-mass flywheel used with the ZF 6-speed transmission should not be resurfaced as you would with a one-piece unit. That could be a cause of your problem.

Normally, a simple u-joint replacement would not create a need for rebalancing the driveshaft.

More of the members will respond with suggestions soon.

_ken

 

[devilfish]

Yes I did machine my FW and yes I know what they say about machin the ZF FW. The shop that did the machine work know about this also and used a waterbased kind of "oil" to machine with, just to save the material between the masses.
And I have checked the "FW lash measurement" like they say in the GM factory manual, and its whitin spec.
And if it whas the FW that was out of balance , shouldent I the vibrations follow RPM more then speed? When I press down the clutch at 130km/h where i got my vibration the rpm drops to ide and i still got vibrations?

 

[muddywaters]

Dev, I'm not familiar with the newer vette drive shafts, but on other autos drive shafts can be assembled out of phase, meaning the yokes are not in perfect alignment. The yokes must be on the same plane, some driveshafts are welded units and cannot be misaligned. Also, try disconnecting the shaft at the rearend and rotate it 180 degrees and reinstall,hope it helps you out. Muddywaters

 

[tkrphxr]

Vibration

Dev you didn't mention how many miles on your car. I have seen a couple of higher milage cars develop a similar vibration due to the tailshaft bushing in the trans wearing. I hope this helps good luck. Charlie

 

[devilfish]

well the car has 90000km on the ODO.
Do you agree that I can count out the clutch/FW to be bad part here? Cause I still got the vibration at 130km/h when I disengage the clutch and engine goes down to idel?

Regards

 

[vette-dude]

I think Muddywaters' response is right on the money. If you did not have the vibes before and do now after the u-joint change then I would suspect that the yokes are out of phase. They have to be re-installed in the same position (plane) as when you disassembled them. Did you mark them before disassembly? If not and you reassembled them 180 degrees out of phase this will give you a vibration. The tailshaft bushing suggestion is another area that could do this but if the vibration wasn't there before the repair work, I doubt it is the cause. Think about how you did this and if you might have put the yoke on 180 degree out. Disassemble, rotate yoke 180 degrees, assemble and reinstall properly and then see what happens. Good luck.

Randy
:cool

 

[devilfish]

ok sounds like a plan..

I whas a bit worrie that I mounted the FW wrong. WHats your feedback on that?

 

[vette-dude]

I believe you can only mount the flywheel in one position as the bolt holes will not line up with the crankshaft holes if it is incorrectly indexed. The mounting holes are purposely drilled offset for this reason. Anybody else want to chime in as it has been awhile since I worked on a clutch set up.

Randy

 

[devilfish]

yeah you know I machined my flywhell ( se abow posts ) im whas affraid It got screwd up..
But if it is the FW setup is should get vibration at a certin RPM range, I dont. I just got he vibe abow 130km/h.

 

[vette-dude]

The FW was only face milled or ground ( I hope). This should have no effect on the bolt hole locations. You have to dress a FW by milling or blanchard grinding after you burn up the clutch plate to remove the gouges, nicks, and burnishing caused by the clutch plate failure. This work does not affect the bolt holes!! It will give the FW a clean, flat , surface for the new clutch plate to break into per se. My opinion, for what it is worth, is that the u-joints are out of phase. The only other thing I think it could be is the ujoints themselves were damaged while being installed ( i.e., needles lost, needles crushed, or yoke damaged during pressing in or caps). Good luck and hope you get it running smoothly again.

Randy
:cool

 

[devilfish]

ok thanks. i keep you posted