vonhayek

I'm trying to help my father resolve a vibration issue. The car vibrates only under braking, and you feel mostly in the seat. The steering wheel does not vibrate nor does the brake pedal. The vibration is noticeable at 70 mph, atrocious at 40 mph, and not discernible below 20 mph.

We have already replaced the front pads and rotors with no change in behavior. I'm starting to lean towards a bushing or ball joint. Suggestions?

smassey321

Could be a rear rotor. Especially since you don't feel it in the steering. Did the shop that replaced the fronts check the rear rotors for run out?

Has your father ever used fix a flat? The goop can break loose and cause odd vibrations.

alchemist

iTrader: (1)

Do a quick test - does it vibrate when you accelerate? what about when you take foot off gas (no braking)?

alchemist

iTrader: (1)

most vibrations stem from rotors (out from what is sounds like), bushings, struts, axles, ball joints, tie rod ends

alchemist

iTrader: (1)

or balance issue with tires/wheels

vonhayek

Don't think it is the rear rotors -- they seem to be in good shape.

He has not used fix-a-flat, but I do not think that it is a tire balancing issue as the vibration only occurs during braking. Were it associated with the tire balancing, I would think that it would be unrelated to braking.

vonhayek

I just didn't know if there were any known issues in the steering linkage or suspension system that routinely caused vibration issues. I plan to get it up on stands and see what I can find.

tomit

Best way to get long life out of rotors is to carefully tighten the wheel bolts in a star pattern using a torque wrench when the wheels are at ambient temperature. Not sure what the ft-lbs of torque is recommended - set my clicker wrench many moons ago.

Tom

alchemist

iTrader: (1)

yes, lower control arm bushings. Search for my DIY thread on this.

There are also steering rack issues with our cars but this may not be related to your issue. Search for that too.

Lastly, some have had axle issues which causes highway speed vibrations. This is why I asked you to do the acceleration/deceleration test.

vonhayek

Thanks. I'll check out the lower control arm bushings. Do you know what specific problems have been found in the steering rack?

To answer your question, I suppose you can say that the vibration occurs upon deceleration -- as I said, vibration only occurs during braking.