For all you guys with the vibration at 1800 rpm and then again at 4000 rpm, come in
12-14-2010, 05:37 AM
#1
For all you guys with the vibration at 1800 rpm and then again at 4000 rpm, come in I did some reading through search on here, I was not the only one chasing this vibration. You could be sitting still, clutch in or out, rev the car and at 1800-2000 vibration and then go away and came back around 4000 and went away as the rpm went up. Did the same with the tach coming down with the foot off the gas.
Short story.... I recently bought a 99 Z28 on here from out of state. When I got it here and drove it for the first time it had a HORRIBLE vibration in the driveline. I diagnosed it as the pilot bearing. The car had alot of miles on it, a buddy had a stock 30k mile clutch assembly and a flywheel out of another buddies car.....so while the pilot bearing was being fixed I could put in another clutch.
Sure enough we pull it down and the pilot bearing is GONE, and had BEEN GONE for quite some time. So it goes back together and is much better but still has a vibration.
So after some reading on here I decide to pull the clutch and have the flywheel balanced. Keep in mind all these cars have "zero" balance rotating assemblies. I walk into my machinists place and he has my flywheel on the back of a LS1 crank on the spin balancer...I said holy ****, is that MY flywheel? Ha says yes, and buddy this thing has issues.
You could SEE the runout(wobble) in the flywheel,It had JUST been resurfaced..... he had been trying to balance for almost 2 hours, had drilled 7 EXTRA holes in the back to try and get it to balance.
I brought another flywheel with me in case he needed it. So after he got done we threw the extra one I brought on the crank and spun it, straight as an arrow. And was in balance, no drilling needed.
I had the other flywheel resurfaced, installed it and this baby is fixed!!!! Smooth as glass.
It appears the other flywheel was over torqued at some point or even originally. When you over torque metal it distorts it.
So there ya go, hope it helps some of you guys.
Short story.... I recently bought a 99 Z28 on here from out of state. When I got it here and drove it for the first time it had a HORRIBLE vibration in the driveline. I diagnosed it as the pilot bearing. The car had alot of miles on it, a buddy had a stock 30k mile clutch assembly and a flywheel out of another buddies car.....so while the pilot bearing was being fixed I could put in another clutch.
Sure enough we pull it down and the pilot bearing is GONE, and had BEEN GONE for quite some time. So it goes back together and is much better but still has a vibration.
So after some reading on here I decide to pull the clutch and have the flywheel balanced. Keep in mind all these cars have "zero" balance rotating assemblies. I walk into my machinists place and he has my flywheel on the back of a LS1 crank on the spin balancer...I said holy ****, is that MY flywheel? Ha says yes, and buddy this thing has issues.
You could SEE the runout(wobble) in the flywheel,It had JUST been resurfaced..... he had been trying to balance for almost 2 hours, had drilled 7 EXTRA holes in the back to try and get it to balance.
I brought another flywheel with me in case he needed it. So after he got done we threw the extra one I brought on the crank and spun it, straight as an arrow. And was in balance, no drilling needed.
I had the other flywheel resurfaced, installed it and this baby is fixed!!!! Smooth as glass.
It appears the other flywheel was over torqued at some point or even originally. When you over torque metal it distorts it.
So there ya go, hope it helps some of you guys.
Last edited by FASTFATBOY; 12-14-2010 at 05:50 AM.
12-16-2010, 03:36 PM
#2
What was the flywheel that had run-out....stock OE, or aftermarket OE-Type, or lightweight, or what?
Overtorqued? I've seen lots of guys use impact wrenches to install them because they're too lazy to do it the correct way....they say "oh, just as long as it's tight as possible that's all that matters".... I couldn't believe it!
Overtorqued? I've seen lots of guys use impact wrenches to install them because they're too lazy to do it the correct way....they say "oh, just as long as it's tight as possible that's all that matters".... I couldn't believe it!
12-16-2010, 10:58 PM
#3
What was the flywheel that had run-out....stock OE, or aftermarket OE-Type, or lightweight, or what?
Overtorqued? I've seen lots of guys use impact wrenches to install them because they're too lazy to do it the correct way....they say "oh, just as long as it's tight as possible that's all that matters".... I couldn't believe it!
Overtorqued? I've seen lots of guys use impact wrenches to install them because they're too lazy to do it the correct way....they say "oh, just as long as it's tight as possible that's all that matters".... I couldn't believe it!
Stock flywheels.
