Dilberto

Above 60mph, the car sounds like it is going to shake itself apart. I have already done the 4-wheel alignment, balancing, and replaced the front sway bar bushings. The front struts are set on firm- but something seems to be amiss still. The only other thing I can suspect is the front wheels are the smaller 15" phone dials. Are these wrong to run with the rear 16"s? The vibration was much worse until I found the strut mount eccentric nut loose on the drive side. The only other replacement is the tie rod end, which was bent.

Luis de Prat

Did you say you had replaced the ball joints in another thread?

Jakerx

i don't think you should be getting vibration just because of the 15's. any other info you can give us?

Granite 944

Bent wheel, out of balance wheels, low air pressure? After alignment you had done, you had no issues with the other wheels? (alignment done with the 15's on front and 16's on rear?) Must be something due to those wheels? Did they do a thorough check of front suspension parts prior to alignment? Sometimes with worn components, it won't hold a good alignment for long......possible?
Tie rod end, inner, outer, and I'm assuming its replacement was before alignment?

Mighty Shilling

Wheel bearings?

Eric

Zach,

IS there an actual shimmy or just an odd sound? If there is a sound only, you may have knocked off a wheel weight. I went crazy thinking my bearings were on their way out--this is after rebuilt A-Arms, alignment, new steering rack, Boges, etc..because I would get this strange sound like a vibration--especially on high-speed sweeper turns. After tearing into the bearings and adjusting them(they were only 1 year old) I still had the sound--upon closer examination, I had knocked off a weight on my passenger front rim.--everything else is perfect, but I still have the sound--am waiting untill I get new tires to get it re-balanced. Check into it.

Charlotte944

15" wheels on a 951? How'd you do that? I thought you had to use 16" or larger wheels to clear the brake calipers.

Anyway, I've dealt with front end noise and shimmys before, so this may help.

First off, make sure the tires are properly mounted, and the wheels/tires are properly blaanced. Have the tires checked for out-of-round.

Have the brake rotors checked for run-out and have them turned or replaced if necessary.

Check ALL front end components (control arms, ball joints, tie rods, tie rod ends, pinch bolts, bushings, etc.) for wear, slop, and so forth.

Check all brake pads for wear and bleed the calipers.

Mount the wheels and go for a drive. Make some hands off (no hands on the steering wheel) "panic stops" and verify the car stops straight.

If you still have a vibration at or above 60 MPH, remove the lug nuts from ONE front wheel and put a dab of paint on the wheel stud closest to the valve stem. Remove the wheel and mount it so the valve stem is aligned with a different stud. Go for a test drive. Repeat. If you rotate the wheel back to it's original position and you still have the vibration, do the same thing to the other wheel.

If you still have the vibration after all of this I would recommend having the tires inspected for some defect like seperated belts.

fpena944

Will out-of-round brake rotors cause a shimmy on the steering wheel even when you aren't pressing on the brakes? I get a vibration on my wheel at low speeds and the only thing I haven't checked or changed are my brake rotors. I'm wondering if that might be the issue.

Charlotte944

If the rotors were out of round (radially) the imbalance would tend to cause some vibration.

However, chances are the rotors are either warped, or have "high spots" (axial runout). When the warped part of the rotor passes through the caliper it sends a pressure pulse through the brake hydraulics. This pulse is typically felt in the brake peddle, but can also cause steering wheel shake or front end shimmy.

hosrom_951

If you check and found everything to be fine (ball joints, tie rods, suspention etc.) then try finding a tire shop that has either updated equippment or a wheel-on-car balancing machine.

I had vibs comming at speeds starting from 80kms/hr (~50mph) and two tire shops couldn't find the source. I took the car down to the official Pirelli tire dealer, balanced it and the problem went away. The technician who actually balanced my wheels/tires said that he found the weights to be incorrect and in the wrong location.

Dilberto

I seriously thought it was also the wheel bearings too. I didnt do the weights because the tire guy said it would require almost 5 pounces of weights per wheel. I want to change them to the proper 16" PDs, if I can find a good pair. The car makes a rubbing sound while turning. I am also beginning to think the rack is bad, because the steering wheel is off center while driving in a straight line sometimes. On other times- the wheel is straight again. WTF? I strongly suspect this because the steering is oscillating from side-to-side at hight speed.

Charlotte944

5 ounces is WAY too much out of balance.

For the steering wheel being off center, chances are that either the last time the car was aligned the "technician" did not denter the steering rack, or the steering wheel was removed and not put back in the same spot.

To find out what the problem is, pull the steering wheel and see if you can get it on straight. If the wheel is always off one way or the other, then the rack was not centered during the last alignment.

Here's another test you can do: Jack up the front end so the tires are off of the ground (you can do one side at a time) and spin the wheel by hand. Listen for any thing that sounds like rubbing or scraping and note where the wheel stops. If the wheel stops at or near the same place every time you spin it, then I would suspect a problem with the rotor(s).