brakes shake. need help

[matt rupke]

like the title says, when i hit the brakes... holy crap does it shake, i think its because of the front right wheel. it was like this before and after i got new pads and my rotors turned. so i dont think thats the problem. theres also a really loud nocking noise when i brake. does anyone have any idea what could be cause this?

[rabidpanda69]

I dont know about the knocking noise, but the rotors are probably still warped if the brakes are shaking. When I had mine turned, they were warped again about 3 weeks later.

[antirice]

pads could have come loose

and you've probably got warped rotors, but technically, you shouldn't feel a pulsation in the rotors as the calpier slides should take care of any thickness variation on the face of the rotor itself

[00SilverGA]

I had this happen to me. When I was braking it would shake quite a bit. I checked it out and the reason it was shaking and making a knocking noise was because of the caliper being loose. If I were you I would also check and see if the wheels are balanced. This can sometimes cause a vibration.

[matt rupke]

ok thanks guys

[fear187]

if you hear a knocking sound (mine did it generally as you slowed down coming to a stop sign.. or a stop)... it is most likely a wheel bearing. (that happened to me, I changed my brakes, then a week or two later a knocking sound developed.. I thought it was something I did... couldn't fix it, took it to the dealership.. and it turned out it was one of the front wheel bearings gone bad)....

[antirice]

Originally posted by 00SilverGA
If I were you I would also check and see if the wheels are balanced. This can sometimes cause a vibration.

99% of the time, not while braking

[Foxy]

Brake rotors rarely warp (http://www.stoptech.com/tech_info/wp_warped_brakedisk.shtml). It's most likely that your pad material is depositing onto the rotors, causing a 'rough patch.' When you brake, this rough patch is minutely thicker than the rest of the rotor, making the vibration. This is also why a resurfaced rotor will 'warp' again in a few weeks - more pad material will deposit on the surface of the rotor, making a new uneven spot.

How hard are you on your brakes? What kind of pads are you running? If you're doing mountain-road driving and constantly heating up the brakes, speeding up, and hitting them again, you can easily overheat the pads, especially if you are running cheap, street/economy-oriented pads. Then, when you stop at the end of your funrun with your foot on the brake pedal at a red light, the material 'cooks' onto the rotor. This is where I'd guess your shuddering comes from.

[matt rupke]

i just got the rotors turned, they were really bad, and im running about about mid pads, they were $33. and im not hard on my brakes at all. and i dont do any off road drving..... its a grand am. it was shaking before i even got new pads and my rotors turned. but it started shaking worse and making the very loud and annoying knocking noise right after i put the turned rotors and the new pads on. so im hoping its just a loose caliper, but i wont find out till tomarow

[Foxy]

Hmm, I'm not sure what mid-pads are. However, $33 bucks is pretty cheap for brake pads. Do you know the brand of the pads?

Assuming that there isn't a mechanical problem with the brake system somewhere else..

Did you break in your brake pads after you had the rotors turned? If not, they could've just deposited more pad material and redid the problem. The problem is that if you really baked on the material, the deposits can be hard enough where they'll remain even after turning/grinding the rotors.

You may need new rotors and pads, and take the time to properly bed them in.

Let us know what you find out!

PS - By mountain roads, I meant nice, twisty, fun roads, not offroading :)

[matt rupke]

as soon as i put the rotors and new pads back on, the first time i hit the brakes, softly while only going about 40, down a very long straight newly paved road, it made the sound and the shaking right away.