Lex-Toyo

I have studied my braking "vibration" further and have noticed that it really only does it at speeds over 50. If I break at around 70mph, it shakes until I get to about 50mph then stops. Is there a tsb out for this, or is this just a common rotor problem? Thanks!

chowder

this was a topic of an earlier thread, i believe. i think mine does this under heavy braking in the 70-80mph range also. it's more of a recent development (last 3 months of a 2yr old GS4 with 20Kmiles). however, i'm waiting till i put some new rubber on my wheels before i blame my rotors. i have bad run-out on my potenzas and am more suspicious of them. just need to find the time to get some tires.
what is your tirewear situation?

Lex-Toyo

My tires are Mich. Pilot gxt z4 and the car has only 21k miles. So, I assume that they are pretty new. (just bought the car 2 months ago, '98gs4)They don't appear to be worn bad or uneven. They actually look pretty new. No other vibrations occur when driving and the alignment is fine. Only problem when braking down to about 50mph, then it stops. Kind of embarrassing.

gs4power

Hi Lex-Toyo,

By the symptoms you described, the problem's definitely related to the brakes. Most likely it is caused by unevenly worn rotors, this is a pretty common problem.

Solution: Have your rotors resurfaced at a reputable shop. Make sure they have experienced machinists and
a well mantained lathe, this is critical. Also, get new pads at the dealer.

Since you detect the vibration at higher speeds, it is unlikely your rotors are warped and need replacement. (You'd feel the vibration at low speeds). The minute irregularities at the rotor surface caused by uneven wear will cause vibration only at higher speeds.

TXSTYLE

iTrader: (1)

Greetings. First of all are you running stock or aftermarket wheels? If they are stock then by all means have your rotors turned and definitely go for a high quality brake pad. If aftermarket, get to the nearest wheel dealer and have some hub-rings installed!

nanotech

iTrader: (2)

My 99 gs4 does that too ! It doesn't vibrate too much, barely noticable actually and its only at high speeds. BUT, it makes quite a bit of noise when I brake at any speed, but not all the time.

My car also vibrates at speeds of around 65-75mph without braking at all, higher and lower speeds are fine.

A friend told me it might be the tires, but to me it has always seemed to be the brakes. I got it checked at Sears one day while I was shopping and they said the brake pads were brand new and that I still had about 15,000 miles left on the tires. They balanced and did the alignment which helped a bit, but there is still some type of growling noise everytime I drive the car and when I brake it is a bit more.

What do you guys think it could be? I don't want to change my tires unless I have to.

chowder

I'll clarify what I'm feeling, cause it's not clear to me if we are all on the same page. I know my car is in alignment and wheels are balanced. The run out in my Potenzas is giving me a lumpy sounding ride, but not a noticeable chassis vibration per se. The vibration I feel when heavy braking from 70-80 mph is felt strongest in the steering wheel. I'm not sure if it's felt throughout the chassis as much.
Unlike nanotech, mine doesn't make noise. As for his 65-75 vibration, that sounds like a balancing issue.
I'll post back when I get new rubber. That will tell me a lot.

gs4power

Chowder,

Again, have your rotors resurfaced and get some new pads, trust me, this will eliminate the vibration WHEN BRAKING.