QikEnuf

Ever since I had the Stillen y-pipe installed and the UDP, flywheel,and clutch I have noticed a vibartion throughout the whole car, it gets even worse with the a/c on. I have also noticed that the car idles normal without the a/c on (aound 650) and then when the a/c is engaged the idle goes up for a sec then back down and then up to about 900 and stays there, that's also when the vibration becomes horrible. Any ideas?

Thanks

Daniel B. Martin

Temporarily remove both accessory drive belts. Since the 4Gen water pump is driven by the timing chain it is safe to run the engine without those drive belts.

If the vibration remains unchanged it is probably caused by the flywheel.

If the vibration vanishes it is related to the UDP, the belts, or the belt-driven accessories. Inspect the belts for wear or damage. Spin the tensioning idler and the accessories (power steering pump, air conditioner pulley, alternator) by hand to see if they turn freely. Examine the mounts for these accessories for looseness.

Raise the car, support it on sturdy jackstands, and slide under. Make a careful visual examination of the Y-pipe. Look for signs of contact between the Y-pipe and the vehicle body. Remember that the flexible engine mounts permit the engine/transmission unit to move (within limits) during normal operation. Pipe-to-body contact usually makes more noise than vibration, so this is not the most likely cause of your symptom.

Dave B

Seeing that you have heavy duty engine mounts, vibration is much more apparent. This is the down side to running urethane mounts.


Dave

QikEnuf

Last week I did lose the tensioner while driving on the highway so the second part of your troubleshooting was done and the vibration still did exist, I was able to spin all the accessories freely and everything appears to be tight.

How or Why could the flywheel cause such horrible vibration?

I have not had a chance to examine the Y-pipe.

QikEnuf

Do you know why this would happen...does it just transfer the vibration to the body of the car?

How did you tweak the HKS intake?

ericdwong

Are these the new motor mounts with the fabricated bodys or the older ones which were core exchange?

Also, without the UDP did you have the poly mounts before? If so, how did vibration, etc feel? From my experience stick cars dont have as much of a problem with vibration at stoplights then autos do.. probbly cause when we're "clutched in" the engine is "suspended" in the engine bay, unlike an auto with it idling against a torque converter.

I want to get the mounts as well but I'm poor. I'm trying to stop my off the line wheelie hop and am prepared to sacrifice some finesse for some performance.

Daniel B. Martin

Losing the tensioner performed only part of the belts-off experiment. The tensioner does not bear on the power steering belt.

An unbalanced flywheel can cause a vibration the same way as an unbalanced road wheel. For that matter, foreign matter caught inside the clutch cover (the pressure plate) can cause an unbalance and consequential vibration.

QikEnuf

They are the fabricated ones..from Place Racing...they are awesome and no I didn't have them installed before the UDP, everything was done at once.



[QUOTE]Originally posted by ericdwong
[B]Are these the new motor mounts with the fabricated bodys or the older ones which were core exchange?

Also, without the UDP did you have the poly mounts before? If so, how did vibration, etc feel?

QikEnuf

Hmm..ok

What would you suggest now..take it back to the mechanic and have them check the installation of the flywheel?

I don't think it's the belts causing this vibration...

Thanks for your help

Daniel B. Martin

Checking the clutch and flywheel requires removing the transaxle. That's a lot of work so you first want to be sure the vibration isn't coming from some other part of the engine. You could take a broomstick and touch the power steering pump, a/c compressor, and alternator while the engine is idling. This must be done carefully to avoid contact with moving parts. You may have to do part of this diagnostic evaluation from beneath the car. This broomstick test might reveal the source of the vibration. It is a process of elimination. The Spotlight Of Suspicion falls on the flywheel if you can't find the source elsewhere.