dinas29

For the past 6 month, I had no issues with my R1 concept Drilled/Slotted dics brake.


But now, when i brake harder, my steering wheel shake a lot!

I think its due to excessive braking at high speed but my question is:

Is there any way to fix this issue beside buying all 4 new rotor?

07cobalt2.2

I have the same problem. I thought by buying drilled and slotted rotors, the heat would dissipate faster and wouldn't cause warppage. Haha.

brycerice13

when your steering shakes like that it means that the rotors are warped. I had that happen with my jeep. Once I changed them if felt good again. Some of those rotors are junk, I have had some that suck and some that are good just read the reviews about them before buying. All you need is to buy the front 2 the back should be fine.

OiangeSS

iTrader: (2)

check your ball joints

ronn

iTrader: (3)

Drilling and slotting makes them more prone to warping because they're structurally weaker. I have had them warp on me when racing (not this car). I would never drill or slot rotors...no need.

BooSSted

iTrader: (3)

My stock ones do it too. I'd love to know the secret to decent brakes on these cars. I had trouble with the brakes on my SC too.

PrincessTurbo

I have thrashed mine pretty good but then again I am on Hawk pads , the most expensive models and they haven't warped yet .

I have noticed some pitting of the drilled holes even tho they are counter sunk but not enough to matter.

are you on stock pads in the front ?

DillySS

Uneven application of braking on the different faces can cause the problem. If you get contaminents on one side and not the other, they will heat unevenly and can "warp". The hotter side will want to expand more than the cooler side. It will be prevented from doing so there is a battle going on. One side will win and yield the other side.

Pulled this from a Porsche site (since most of their vehicles have drilled rotors) and I have to say this is probably the most intelligent thing that I have read in a while. This is what is happening.

Malaclypse

iTrader: (1)

Mine are doing it to, but ever so slightly. At 10k miles I guess its allright. By the time the rotors get bad enough for me to want to turn then, it'll be time for new brakes anyways.

Omnigear

iTrader: (4)

y hawk pads on the lnf >_< the oem is better.

get blank brembos n get it slotted if you want.

BackInBlack

I barely have 5000 miles on my car and I can already see what you guys are talking about. Only time will tell, but I think the brakes just require to be serviced regularly. A Brembo setup like that is just begging for seizing parts, with those slide pins and the way they sit within the caliper. Taking them apart regularly, I'd suggest, is the only way to keep on top of it. Hell they work amazing when they're completely serviced... I've already noticed a difference. I've chamfered the pads, scored the rotors and lubricated the slide pins twice already.

CrystalRedSS

make sure your lug nuts are not overtightened. tight lug nuts will cause your rotors to warp. they should be set at 100 ft/lb.

TommyP

iTrader: (2)

This is kind of irrelevant. There are certain ways to do drilled rotors correctly. The OEM Porsche rotors, and the ones that come on the corvettes and such are forged with the holes in them. Their drilled rotors are not originally blanks like ours start out as, so they don't have the same issues that we do.

blackbird

Vibration or pulsation in the steering wheel under braking is generally caused from warped rotors but it would still be a good idea to do a full inspection of the suspension and make sure nothing else is worn. Warped rotors can be caused by excessive heat, normal wear, and manufacturing/machining defects as well as improper torque on the wheel lugs. That's why it's important that you always use a torque wrench and tighten gradually in a star pattern and make sure the mounting surfaces are clean to minimize this.

Also are you on the stock wheels or aftermarket? If you swapped out to a wheel that doesn't have the Cobalt's exact hub diameter you can sometimes get vibration which can be more pronounced under braking from the wheel not being centered and torqued correctly. A correct hub-centric ring can minimize this but you still have to be careful with some of them such as the cheap plastic ones that still allow a little too much slop/play when mounting the wheel on the car. Also from the factory most cars use a little clip over one of the lugs to hold the rotor in place on the assembly line. Often the stock wheels will fit over this clip but if you switch to aftermarket wheels they won't sit flush and when you torque them down can lead to rotor warpage.

dinas29

All my nuts are torqued to 100 lbs with a torque wrench i baught. I'm running on stock wheels but i installed the rotors along with all hawks pads.

Nighthawk243

Generally it is warped. If they're not too thin, you can get them turned on a lathe.

DirtyBalt09

iTrader: (2)

Mating surface between pads and rotors is very important also. If you turn or change out your rotors replace the pads too. But on a side note drilled and/or slotted cannot be machined.

dinas29

Ok so i guess my best option would be to buy new front/rear rotors like the ones that Mpx sells?

quikdcride

ive been given alot of warning about the drilled and slotted.
what about just slotted you think those will pose the same problem with warping?

tom.g

iTrader: (4)

No, by drilling the rotor you removed a lot of the material from the rotor in turn making it weaker and more susceptible to warping. As has been discussed on this site many a times the only advantage to drilled and/or slotted rotors is better wet braking performance.

That's a good explanation.


Out of curiosity does anyone know what is a good thickness to replace the front & rear rotors at? Mine have developed quite a lip and are even a little grooved (both F & R) and the car only has 15k miles on it yet the pads are fine on all four corners. I'm thinking about either having the rotors machined or just buying all new rotors.

Wangspeed

iTrader: (2)

No they aren't. Zimmerman stopped doing that for Porsche ages ago. All the drilled metal rotors crack. Porsche, Corvette, Ferrari, you name it.

Warped rotors are rarely actually warped. It's usually due to uneven pad deposits by bad pads, or pads that are used out of their optimal heat range.

quikdcride

good explination wangspeed
what kind of rotors do you run? think i should just get some slotted?

BackInBlack

More often than not, 'warped' brake rotors are felt through the brake pedal. It's feedback while the pad 'hops' on the sections of the rotor that it still mates to. I have seen on a few occasions where you will NOT feel any feedback through the pedal, and more the steering wheel. All of those cases were at high speed braking. 65mph+ once the brakes were applied you would get a shimmy in the steering wheel that would soon disappear as the vehicle was brought down from speed.

Things like this are hard to diagnose through a keyboard, without the car in front of me. It seems many of you are afraid to take your cars to a professional for many reasons. Past headaches, poor workmanship, etc. I get it.

But you'll be more upset if you throw parts at your car, spend $300 or more, only to have the same problem arise after you're done. Can't hurt to have the car inspected by someone who knows what they're looking for, and is trained to do so.

blackbird

The rotors should normally be replaced when they are at maximum lateral run-out (i.e. when one part of the rotor, inside or outside diameter, is thicker or thinner by a certain amount than maximum recommended variation), when they reach minimum thickness, or if they are warped or have grooving when you're replacing the pads. On cars where the pad's surface area doesn't extend fully to the edge of the rotor it is common as the rotor wears down to leave a lip. Surfacing (machining) the rotors can be done as long as it doesn't take the rotors below minimum thickness (normally stamped onto the rotor as well as listed in the factory service manual), but with how thin many rotors are from the factory for weight and manufacturing savings the general recommendation on most newer cars is to just replace the rotors.

For a regular daily driver you might be perfectly fine with a light surfacing but if you have to take much material off and get down close to the minimum service thickness there will be less material to absorb heat and it might not be the best idea for a performance type vehicle. If the rotors are still within service specs but just have light grooving I'd personally continue to run them until you have to do a brake job and replace the pads along with new rotors at that time. Also keep in mind that super aggressive brake pads can provide significant improvement in braking performance but it does come at a cost and that's usually rotor life so factor that in if you're planning for future brake system maintenance.

RoadconeTuning

THIS... you probably cooked your pads and then stopped leaving huge deposits on the rotor and you're feeling them grab unevenly around the rotor now...