i have a 06 cobalt ls. just put my new 18's on it and i got eibach sportlines. nothing appears to rub and when driving its smooth, when i brake at speeds over 35 or so, the car shakes. the harder i press and faster i go the more it shakes, then when i get down to about 30 it smooths out. i kinda also noticed that when braking it seems to pull the wheel one direction or the other, doesnt happen everytime so im not sure if thats just some of our poor roads. would really like some help

 

What are you using as far as shock absorbing?

 

alingment? (spelling??)

 

yeah man i had the same problem, i thought i had warped rotors. but i tried to take mine off to get them turned and i couldnt get them off. so i put the wheels back off and it doesnt do it anymore. wierd huh?? maybe it was something on the brake pads or something. idk. if you find out what it was, let me know.

 

the alignment would have nothing to do with this shaking, if it was off alignment, then the car would shake at all times, that and unbalanced wheels.

 

yea all i really could think of was to get an alignment

 

I agree. An unbalanced wheel or two could definatly be the cause of the vibration, but not so much during breaking. A wheel balance problem would vibrate at certain speeds while normal driving or driving period. I had snow compacted in my wheel which threw off the balance and that gave me a crazy vibration. Sounds like his problem has to do with the brakes. Rotors, pads, ect...It's the small factory pads and rotors. If everything looks normal, then the problem is just that the stock rotors don't dissepate the heat well and the stock pads suck..Good luck

 

Its all in whether you torqued the lugs evenly when you put the new wheels on. Most tire shops use a torque wren ch to make sure that they are even. If the lugs were unevenly torqued, the rotor is being pulled harder in the direction of the looser lugs and pushed where they are tighter causing some runout of the rotor and hence the pulsing that you feel. You will probably need to get the rotors turned or new ones to get rid of the problem.

 

alignment shouldnt have anything to do with it. did you get your lug nuts retorqed after 150 kms of driving? if yes, then i would say check your rotors....when the tireshop put your new wheels on, they could have overtighten the lug nuts, on smaller cars(ie geo metro) it is very easy to overtighten lug nuts causing the rotors to warp. this could of happened....

 

Not sure if this was mentioned but i hope you have hubcentric rings with your rims.

 

guys did you not read my first post, i dont think anything is wrong, i had the exact same problem. i would take your tire off and put it back on. at first i had the problem, then i took the wheels off, sprayed the center of the rotors black (stupid rust), put them back on and the vibration was gone. so i dont think anything is wrong here.

 

well i have taken them off and put them back on, didnt cause mine to go away so you think new rotors and/or better brakepads would stop that?

 

put your old wheels on and see if it acts normal. In my opinion, if you put new wheels or tires on, always get an re-alignment. New wheels or tires, ALWAYS need to be re-align stupid but try putting old ones on and see if it still does it.

 

Actually the hubcentric wheel thing could be the problem. All GM's are hubcentric and if your using Lug Centric then you'll definetly get vibration out of it.

And if the wheels you upgraded to are heavier than stock then you need to upgrade your brakes. Number one problem with wheel upgrade is not upgrading brakes which should be a standard.

Edited to add that an alignment shouldnt be the cause of his problems. Maybe if it was the road he was driving on, but not every road every time.

 

I put 18's on mine and theyre fine didnt notice a difference...I havent noticed any difference in my brakes either

 

My mom's infinity was real shaky when breaking and it ended up being warped rotors, i think they machined them straight again. No problems now for her.....

 

Do you have one of these behind each wheel or not?

 

mine did the same thing, it needs new brakes, chevrolet has put out a service bulletin on the 2006's the ROTORs are grooved, pitted or warped, (rub your fingers over them AFTER THEY ARE COOL! and if they arent perfectly smooth, they are bad.

 

God help you if you're too stupid to wait for them things to cool down. They can easily be >500F without you being able to tell, assuming you were just on them pretty good.

I've had problems with my car pulling randomly when I stop sometimes. Stock wheels and everything. Doesn't do it all the time, but in my case it is definitely due to an uneven road surface.