Well I posted awhile back after getting my new rims I had a pulsation in my brakes, when braking from 45 mph or higher. I got the rotors turned and everything was all gravy. well the pulsation came back and I decided to pay closer attention to it this time. Yesterday i was on the highway, and I tapped my brakes and the pulsation is coming from the rear. Could the drums cause a pulsation? and if so, what do I need to do to get it fixed? i plan on doing a brake conversion, but that won't be until further on down the line as I am broke. somebody please help!

 

well i remember when i first started driving my cobalt and treated my car like **** i had to get new rotors twice within 4 months... Have them checked again, thats the most likely problem, it can happen any time if you break to hard or break while going over speed bumps, the 2.2 stock rotors are very flimsy. Also have your wheels balanced.

 

i dont know if the cobalt is like my HHR but my car had little retainer rings on the drums and rotors that went over the lug studs, and when i didnt take those off with my aftermarket wheels the brakes puslated.

 

its hard to warp a drum, i'd check the runout on the front rotors, check the wheel balance, and make sure the wheels are torqued properly. if you overtighten the wheels it could technecly warp things.

 

i know it's been awhile so i'm updating this thread. i got my new pads and rotors put on today, i got the ebc dimple drilled and slotted rotors, and hawk hps pads... so here's for the news. i drive home and when i exit off the highway i still get the pulsation... the brakes work a lot better than the old ones but the pulsation is still there... not quite as evident, but you get the picture. my question to everyone is, should i wait for the recommended 200 miles for the new brakes to break-in? or is this likely a problem that won't be fixed by that? if so what could the culprit be?

 

If you truly believe the pulsation is coming from the rear pull the parking brake handle while your driving down the road at speed. This will isolate the rear shoes and drums so you can really see if they are the problem. If you find that the fronts are the problem there are really two things to do. One make sure you are torquing the wheels properly, excessive lug nut torque can cause rotor pulsation. The only other recommendation would be to have the rotors turned. It is possible to turn drilled rotors, GM has stated that Corvettes cross drilled rotors can be turned and I myself have turned a set. Best of luck.

 

the rotors were just put on today and they're brand spanking new... i don't believe they would be warped that quickly... and i didn't torque the wheels down, the shop i got the brakes put on at did all the work.

 

Brand new doesn't mean correct. It is very unlikely but possible to have new warped rotors. Just depends on the tolerances from the factory. That was the only 2 reasons I could think that the brakes would pulsate. Did you check out the rear drums like I suggested?

 

Hope tha following link helps. There was something over tha clips from tha factory that made tha shake'n. Everything is smooth since they were removed.

https://www.cobaltss.net/forums/wheels-tires-96/braking-shake-new-rims-76395/