We think the motor is toast in my cousins coupe.In a nutshell,very bad vibration only at 4000rpmsand up,other than that very smooth,thought it was a clutch problem,put a Spec stage 3 in with new pressure plate and a billet steel flywheel,not the clutch.Also the tranny (TKO) bearing retainer was broke,fixed it also.Still the same vibration at 4000rpm.He also checked the balancer and no signs of spinning,and it's in the same place as installed 2 months ago.And ran the motor without the belts on,same.It does it weather the clutch is in or out so it's not coming from the clutch back.We gonna put a different ballancer on it tonight just for piece of mind before we tear the motor apart.Were starting to think it might be a rod possibly the crank.Any idea's.The motor only has about 600 miles on it. Thanks

 

it could be the crank..I had a vibration in my motor. I changed the balancer to a ATI took it for a test drive and at 2,500 rpm's the crank decided it wanted out....see ya..buh bye.

 

Sorry to hear it Bryan.... Let us know what you find out...

 

is there a miss along with the vibration?... like its running on 7cyls?... Thats very close to what my car was doing. Did you check the plugs yet?... how about compression test?... Did u get the clutch in a go driving and it started? Or is that the reason you put the clutch in to begin with?...

 

The car didn't do it till the night we raced Ray,on the way home we felt it and thought it was the clutch,well the new one's in and the vibration is still there.Compression is fine and no missing,I think it's a bent rod or a broke crank.The funny thing is no vibration and the car runs smooth as hell till 4000rpm,then it shakes real bad,almost like a spun balancer.

 

I'm sittin here thinking,could it in any way be a bent input shaft?Or would it vibrate at any rpm?

 

Does it do it on a dead rev?... or only when your driving it?....

 

It can be in neutral and still do it.

 

i'd find a balancer first and put it on, before you tear into the motor... other than that I'd be looking at a rod..