Well I just put my new rims and tires on my balt, the rims are 18x7.5 DCrims 340 mesh, I bought them off of wheelfire.com. the tires are 225/40/18 nitto nt555. the problem that i'm having, is that when i went driving, whenever i got around 40-45 mph and then tapped or hit the brake, i had a slight wobble which felt like it was coming from the front passenger side. any idea what this could be??? any help would be great!!!

 

loose / missing lugnut?

 

Yeah, check your lugs man. Tighten them in the correct pattern?

 

Tighten them in the star pattern to 110 lb/ft.

make sure metal retaing clip put on from factory , is off from the side of the rotor. there would be 2, theyd be wrapped around the studs, used to help hold the rotor on while it goes down the assembley line. Ive seen these cause vibrations before.

 

improper balance. take it to a tire shop and have them test the balance. It could also be just a bad tire and a belt has slipped. I would also check the lugs like exiged said. I don't trust those shops any way so when I have anything done like removing and replacing rims I always recheck the lugs.

cheers

 

yeah, i tightened them in the correct pattern. i'm gonna re-check them in the morning before i go to work though. the only thing is that i don't have any wobble when i'm driving, it's only when i go to brake. i hope somebody else can shed some light on my problem.

 

unbalanced wheels it sounds like to me

 

Warped rotors? That will cause shaky vibrations while braking. If you done a lot of quick stops lately it could be that.

 

unbalaned would be constant at that speed and you would feel it when driving steady, accelerating, and coasting. could be the rotors, give them a look.

 

i don't see why the rotors would be warped, i never do any quick stops. i'm going to take them to discount tire tomorrow and have them check 'em out. or i might do it at wal mart since i work there... might get it done for free. not sure yet though. thanks for all the help and if anyone else has advice feel free to share it.

 

I have seen more cobalts come through the door with warped rotors and the like then any other GM car it seems. dont ask me why , but they do. give them a check though.

 

yeah gm rotors on the balts are ****... mine has warped twice in the past 6 months.. i had em turned the first time and they just warped bout a weekl ago for the second time.. im gonna get some drilled and slotted ones to fix the problem this time..

 

i have beome a master at machineing rotors. All thanks to the sub-par materials used in the obalts brakes system.

I havent seen a clear cut ansewer yet as to why they have this problem either. I just hope GM gets it all sorted out real soon.

 

so if it is indeed the rotors, will that be covered under warranty? i'm at 39,000 miles right now. i've just never had this problem and now all of a sudden when i put my new rims on i have this. it's aggravating and on top of that i have a 20 mile drive to work everyday.

 

I actually do believe it is a known problem. We have covered a few under warrenty. mostly 2.2's and 2.4's. It is aggravating if that is the problem.

I have a 45 mile commute too. i know the feeling. haha

 

unbalanced. and by the way nitto 555 wear pretty fast.

 

If it is the rotor it will be covered under warranty. I have had mine turned twice now and they said that if the warp again they will replace them with the GMPP drilled/slotted rotors.

 

i'm not a real spirited driver so i don't think i'll be too bad with them wearing. but i guess i'm going to have to drive to work tomorrow on these, and then on friday i'll try to get it in to the dealership. they should provide me with another car to get to work while they are performing the work on it. hopefully i'll get this figured out but i'm still gonna run by discount tire for ***** and giggles.

 

I don't know if anyone mentioned this yet, but get hub centering rings for those wheels if you don't already have them. I've had many "mystery" vibrations on cars with aftermarket wheels come into my shop and it's because they're not hub centered like the stock ones. I have them on my MKW 18's and they ride like my stock 17's.

 

LOL........ROFLMAO

1) The stock rotors are pretty damn good actually. The pads are the source of the problem.

2) Putting drilled and slotted on doesn't fix problems, it creates a lot more.

I'll give ya the answer.....the rotors and pads are an EXTREME mis-match. I had stock pads and rotors on my car for the first 36,000 miles. Before 10k the rotors were already getting grooves in them.

At 36k they were completely gone. I replaced the rotors with OEM blanks and Hawk HPS pads. I've put 20k on them and they're smooth as glass and have yet to start really showing wear. This is with almost 400 miles of road racing on them, 5 auto-x events, and spirited driving. So the OEM rotors will last like a champ......so long as they're not matched with OEM pads.

LOL beat me to it, that was going to be my next question. A lot of people don't realize some wheels are hub centric and some are wheel centric.

 

i have the hub centric rings on them, that was the first thing i made sure i put on. it turned out that the rotors were warped, so i had them machined today, everything is better. the only other question i have now is will the new wheels, being bigger than my stock 15's, affect ride quality? i noticed that my ride is a little bumpier, but i haven't lowered it yet. i'm thinking that maybe new springs will make the ride smoother again.

any advice???

 

Tires are actually part of the suspension system. As you aspect ratio goes down aka, th thinner the tires, the more bumps your gonna feel. Thats why riding in a toyota camry is a little smoother then say the SS. just a crude example. springs wont help at all reallly

 

that's all i needed to know, it's not like its a huge difference, but getting into the higher speeds it is kinda noticeable. but i think it might just be me needing to get used to the new ride also. in my last car i noticed a little bit of difference in handling once i lowered it, enough so to notice a lot of the bumps went away. guess i'll have to wait and find out. now what springs should i go with? i noticed that the sportlines are pretty popular, but at the same time they're quite a bit more than the progress lowering springs, which alot of other owners seem to have... any advice on this. i like advice from you guys.

 

If you're going with lowering springs, the ride is going to get somewhat harsher, not smoother.