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-   -   vibration (front end) (http://forums.pelicanparts.com/911-930-turbo-super-charging-forum/455549-vibration-front-end.html)

Tomy 02-05-2009 12:31 PM

vibration (front end)
 
I have new problem:

I have replace front and rear brake rotors as well as pads. (just made 80 miles)
I have some vibration at 65-75 mph on steering wheel.
During braking from this or higher speed I have even more vibration.
I have balance front wheel and result is the same.
Tires are OK too.
Bearings are Ok ( I checked it when replace rotors).
What it is?
What about running in rotors? (but it should be only when braking yes?)
I have made geometry as well all factory (without camber that I set to rear -1.5 and front -1.0)
Any idea?:(

A930Rocket 02-05-2009 03:41 PM

Not sure if it relates, but when I'm at the track with "broken" in rotors and pads, the front brakes pulse and vibrate until they have really broken in. Could be you need to drive it more.

If that doesn't work, then I'd re-check the wheel balance and bearings. Heck, maybe check them first.

Where did you get the rotors from? Aftermarket rotors suck imho and they might be your problem.

Good luck.

willtel 02-05-2009 04:01 PM

Were the wheels and tires balanced while they were on the car or on a separate machine? Floating rotors?

These cars have so much steering feel I think on car high speed balancing is worth it.

Benny771 02-06-2009 05:42 AM

Im a believer in the offset of your wheels has a lot to do with it.
Have you checked your wheels for a bend on the inside(damage).

Dynamohum 02-06-2009 06:54 AM

Quote:

Originally Posted by Tomy (Post 4466875)
I have new problem:

I have replace front and rear brake rotors as well as pads. (just made 80 miles)
I have some vibration at 65-75 mph on steering wheel.
During braking from this or higher speed I have even more vibration.
I have balance front wheel and result is the same.
Tires are OK too.
Bearings are Ok ( I checked it when replace rotors).
What it is?
What about running in rotors? (but it should be only when braking yes?)
I have made geometry as well all factory (without camber that I set to rear -1.5 and front -1.0)
Any idea?:(

Seems like you already ruled out the wheels and tires with balancing.

Does your vibration change at all with a slight application of the brakes?

Providing your bearings are good and properly installed and you haven't changed or done any other work outside of replacing the rotors (I'm assuming with new rotors that have not been previously machined?) If these are used rotors or if they have been machined check and make sure they are running true.

Mount a dial gauge to measure the surface of your rotors while mounted on the car, rotate them by hand and check for run out. (sorry don't know the spec off the top of my head but its very small) (it only takes a few thousands run out to cause vibration that will be felt in the steering wheel)

This type of problem is often traced to dirt or rust on the hub. Check your rotor mounting flanges, make sure they are clean, true and free of any dirt rust, nicks or bumps. It only takes a small amount of crap to cause this type of problem.

If they measure within spec, on run out, check that the 2 rotor faces are concentric, (a few thousands will cause feedback via a pedal vibration)


Hope this helps you out

fredmeister 02-06-2009 11:33 AM

I had a similar problem that appeared to shake the front wheels but in reality it was a rear tire that was delaminating on the tread and was transmitting vibration thru the entire car. It was really wierd and felt like a steering issue.
Only ocurred at higher speeds because centrifigul forces would start to pull the rear tire tread away from the carcass. Found it by accident when removing rear tires and rolling along the ground and noticed a slight bump as it rolled along.
Worth a look at least.

Tomy 03-30-2009 08:55 AM

Hi,

So Fredmeister have right! I have put new Rota fox with new Toyo tires and vibration disappeared. But in my case it was front tires and Antara wheels.


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