I once had a 1991 GMC truck.
The pressure plate failed.
The clutch pedal would go to the floor, but the clutch wouldn't disengage.
I shut off the truck and stuck it in 2nd gear.
I started the truck and it took off down the road.
I pulled into the nearest GM dealer.
They put in a new pressure plate, clutch, throw-out bearing and resurfaced the flywheel.
After driving the truck awhile I noticed a vibration.
With the truck parked and in neutral if I pressed the gas pedal slowly,
gradually increasing RPM, I could feel a shake in the gas pedal.
I told the GM Dealer that did the repair about it.
They told me that I drove the truck to their garage and they have
no way of telling if the truck had the vibration before the repair.
I complained to the owner of the dealership and he said if they took it all apart
again and nothing they did was wrong, I would have to pay for the labor.
I said do it and that it did not vibrate before the pressure plate failed.
Well, it ended up that the New Genuine GM pressure plate was 18 grams out of balance.
The service adviser told me they asked the machine shop that resurfaced the flywheel,
to check both the flywheel and pressure plate together for balance.
I guess the only way to check a pressure plate for balance is to mount it to the flywheel.
The machine shop said they could weld a weight on the pressure plate to balance it.
The service adviser told them not to touch it, because they needed it as proof so they could get reimbursed for their labor.
When I picked up the truck, I told them that if the rear main bearing seal starts
to leak or if a tranny bearing starts making noise, I'll be back.
Lesson learned:
It might be a good idea to check if the flywheel, pressure plate and clutch all mounted together, are balanced before installation.
I'm not sure if you can balance, with the clutch disc sandwiched between the flywheel & pressure plate.
