and its not hott. at about 4,000 - 4,500 rpms, it starts to vibrate really bad. clutch chatter? i just put one in without machining the flywheel. what do i do?

 

Clutch chatter would be while you're slipping the clutch.

 

Check driveshaft ujoints

 

can u replicate at any speed, if its at 4000rpm while sitting still it wont be drive train

 

It could be a lot of things man you're best bet is to look at the engine while someone in your car is revving it to around those rpms and see if anything is visibly loose or needs replaced

 

it was the bolts that held the fan onto its pully, one was missing and another was loose. None of them were really tight either. I couldn't see anything on the motor vibrating... crazy. It took a lot of power and throttle response. I fixed it with new shiney steal bolts and its awesome now.

 

Is it vibrating at idle or going down the road ?