lowered car = drivetrain vibartion??????

Ok here is my problem I recently had some suspension work done Eibach
pro kit springs, Bilstein shocks & struts, Steeda aluminum upper and lower
rear controll arms , steeda ball joints and bump steer kit, offset rack & pinion
bushings and maximum motorsports cc plates (installed 2 weekas ago). Obviously the car handles much better But now I have a vibration in the drivetrain I believe, feels/sounds sounds alot like tire roar but only hapens when on the throttel as soon as you get off the throttle it goes away and comes back as soon as you get back on the throttle again not real loud kinda harmonic. My car is a 2003 GT automatic with no track time YET I have a chip (JMS) that corrected my speedo with gear install 3.73 (10 months ago) and has three settings all settings have improved shifts and the most agressive has pretty firm shifts my questions are as follows.

1) I run in the most agressive chip setting almost all the time, shifts even at low rpm's are firm and fast could I have worn out my U-joints already

2) Could my aluminum d/s be out of ballance

3) are there any aftermarket u-joints, upgrades = better than stock
4)Do carbon fiber drive shafts absorb more sound and vibration than aluminum
and are they lighter

Any help or suggestions on this would be greatly appreciated and remember I didn't notice this before suspension upgrades

THANKS

jfranci3 said:

1) did you have your car aligned after your CC plate install?

2) Did you change your pinion snubber?

3) Are the Control arms adjustable? Your pinion angle could be off

4) Did you buy cheap gears? The rear end in our Chevy van did exactly as you are describing. It had a defective rear end.



Carbon Fiber does not asorb shock at all. If fact, a lot of people believe there ds's are too stiff.

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1) yes it was aligned after install

2) I don't know if they changed the pinion snubber ( the install was done by a "reputable shop")

3) control arms are non adjustable

4) FRPP 3.73 gears installed w/ FRPP aluminum d/s same or less vibration than stock.

5) on the carbon fiber d/s I would like more opinions because I thought that
they were supposed to absorb more vibration than aluminum?
here is a link with info unless it's www.need-4-speed.com/pst.htm

Thanks for your help anyone else

Islander03GT said:

sounds like your pinon angle is off to me. that happens alot on lowered vehicles.

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1)How do I check

2)How do I fix

any other opinions on carbon fiber d/s ( read posts above) and vibration even if it's not my problem Im considering it.

c2see21 said:

well i just lowered my car & had a similar problem. it ended up being the front wheels were out of balance. i took it back to sears (where i got it aligned) & they fixed it right up, & viola.... no more shimmy hope it works for ya, cause i know it gets real annoying, real quick

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Thanks but I don't think that can be my problem it happens when your on the throttle lets say 50 55 mph but if you get off the throttle it goes away until you get back on the throttle

p.s. it happens at all speeds but is worse at some speed than others.

HELP IT'S DRIVING ME NUTS!!!!!!!!!!!!!!