mean vibrations....

[SicMonte]

i know that this a very vague topic...but i just want to get some opinions....

The symptoms:
1) vibration in the car...not the steering wheel...at around 60-75mph. not rpm related but SPEED related. I cam feel the vibration through my harness shoulder straps alot!!!..which are connected to the cage
2) very very very violent vibration at around 110mph. This was so bad...the noise from my floor boards vibrating made me immediatlly let off the gas and pull over.

This all started to occur after I got my cage insatlled and all my body mounts replace.

Solutions:
1) balance tires...already done that.
2) balance driveshaft
3) new harmonic balancer on the motor...I have a pro-race one on there now but it is over 5 years old.
4) any sugestions?

[4MuscleMachines]

I would check my driveline angles.

[big gear head]

Is this a stock drive shaft or after market? Stock drive shafts tend to distort at higher RPMs. This shows up a lot after a rear gear change or when going to an over drive transmission. The drive shaft might be in perfect ballance at lower speeds, but at higher speeds it will start to flex and go out of ballance very quickly. The fix is usually a larger diameter shaft or a more rigid shaft. Check with www.iedls.com and see what they have to say about it.

[SicMonte]

it is a stock driveshaft. I read that article on the website you posted a link to....that mentions low rpm/speed vibrations...mine was at high speed and high rpm's.

[MonzaRacer]

Before it comes through the floor.
Give Dennys or one of the other companies a call and get a DS made that can take high rpm. IF not you may have the old one up your behind.
The stocker in perfect shape is only good to about 80 -85 mph at best
Good luck
Lee