Dean98TA

How many of you with heads and cam, or with a stroker notice your motor vibrates at RPMs quite a bit more, as if it's not balanced correctly?
Mine does, but the funny thing is, it doesn't do it all the time. Sometimes it's smooth, but I'll shift a few times and it's rough. Now you may be thinking Aha! There's your answer - the drivetrain, but it doesn't vibrate when I push in the clutch, only when the drive train is attached to the motor.

I had my motor dynoed and it's over 400 RWHP, and the dyno plot was really smooth compared with others that day that had very wiggly plots, so I don't think it's a cylinder not firing or a low compression problem.

I'm curious if it's just a normal manifestation of more power, or if there's a subtle problem that needs attention.

Anyone else notice this?

Nine Ball

iTrader: (38)

I haven't noticed anything like this with any of my setups Deano. Could it be driveshaft related perhaps? I've heard of some of those being out of balance.

Tony

Slow Z28

iTrader: (19)

if it doesn't happen when the clutch is pushed it, could it be something having to do with the clutch disk or pressure plate? maybe something with the throwout bearing? cause then when the clutch is released and the gear is engaged, all those things start spinning again along with the motor. anybody have the same thoughts?

Chris

Nine Ball

iTrader: (38)

Chris, the flywheel and pressure plate are always spinning with the motor, they are bolted directly to the crank. Its just the input shaft, disk, and drivetrain past the tranny that is not turning anymore when the clutch is disengaged.

Tony

LS1derfull

Extra cam duration at the same lower rpm under a load will shake more from being less efficient in this lower range of use.

Slow Z28

iTrader: (19)

got ya tony. youre right. i wasn't thinking fully about it. been out of the 6speed game a while and into the auto <img src="gr_stretch.gif" border="0">

chris

Dean98TA

The vibration occurs at higher RPMs (> 3000) but only at part-throttle. Let's say I'm at 1/2 throttle and easily accelerating to 4000-4500 RPMs - thats the range where I get lots of vibration coming up through the floor, the tranny, and it even makes my rear hatch latch squeak. But it doesn't do this all the time, I'd say it does it about half the time. Its almost like I have a cylinder out, but when I go WOT, the power feels smooth.

Anyhow, seems like only a couple other folks I've talked with have experienced what I am so I'm starting to think I need to do a leakdown or compression test just to satisfy my curiousity. <img src="gr_stretch.gif" border="0">

Thanks again!

Dean