Own a 2002 e-30 4matic- 34,000 mi. Could use some advice. brought my car to the dealership complained about pulsating/vibrating brakes around 70 mph as well as thumping while driving at slow speeds. So far SA informed me that although my pads have a-lot of life, all 4 rotors are warped. Front rotors were replaced in the end of Sept, 6,000 mi. ago. I asked if this appeared normal and he indicated that the rotors would warp if someone rides the brake, which I certainly do not do. I've only had to replace one set of rotors in my life (4 cars) and that was at 104,000 miles. My question is if I pay the $1,200. they are requesting because rotors are a " maintenence item", will I have the same issues again? I believe there must be something else causing the rotors to warp. The ball joints were replaced 1 month ago. Could this be the cause if warped rotors? What else should I be looking for? Thanks for any input.

 

Ball joints will not cause ant rotor problems. Warping comes from brake overheat and overheat is caused by excessive braking or the rotors dragging like from riding the brakes. This is not a common problem with any MB's.

 

Do you wash the car yourself? On hot rotors, a cold splash of water will warp them.

Also, I'd never pay $1200 for a set of rotors unless they were made by God himself. I can get a set of premium Brembo OEM's for your car for less than $250.

Your dealer must be charging 1000$ for labor!

You must be replacing them with Brembo Sport Slotted Rotors (very nice!) because a set of four of those cost 714$. I guess @ 50$ per hour of labor, your dealer must take six hours to install rotors. Either an incompetent dealer, or they must be doing some INSANELY good work!

 

Aren't those Brembos for $250 just rebadged Zimmermans?

 

The plain face ones? Probably. I wouldn't know though, I just got those prices from Tirerack to compare with.

 

Rotors would have to be VERY hot to warp with wash water. It can happen but is not as common as one might think. Beleive it or not, holding your foot on the brake pedal for a few minutes on very hot rotors will warp them faster than wash water. When was the last time you saw an MB dealer charging $50 per hour? More like $90!

Rotors might be considered a wear item and not covered under warranty but only if they are worn out. I would argue that they are made from inferior material and are therefore defective and should be covered under warranty. If they deny the claim, I'd take the car to an independent shop. they can do the job for half of what you were quoted.

Good luck.

 

$90 an hour?! Insane. Seriously. I have a shop that I love that does most of my work, he charges whatever he feels like it

Usually, about 25$ an hour since I always talk with him and stuff when he works. Real cool guy. That's what's great about going to the not so good parts of town. The prices are really good and the guys are fantastic to work with.

I didn't know about the probability of not warping though, that's good information to know! I used to always give the car a 30 minute cool down period before I washed the car. That's 30 minutes I could've spent Zainoing!

 

Wow $25 is a damn good deal. If he does good work, you are a lucky guy. Dealer rates are going up becasue of the increasing legislation, taxes, etc but mostly because mechanics are required to take more training. Check out the amount of hours they spend learning how to repair every little sub-system on these cars.

30 minutes cool down certainly helps stay on the safe side. Hot wheels are hard to wash (soap dries too fast) and it is just about enough time to have a cold one!

 

Warp rotors usually refers to uneven brake pad material deposits on the rotors. This can happen on a set of rotors that are not broken in properly and even on normal driving where you are sitting in traffic with your foot on the brakes (although I feel this will only happen if it's a long light more like waiting for a train to pass), the result is the spot where the pads make contact with the rotors leaves behind pad material that is different thickness with the rest of the rotors. As you described the vibration at 70mph would mostly likely be it.

 

Thanks for all of the input. I bought my car (starmarked) in DEC. and have only put 3,500 mi. on it. I have a feeling the prior owner really beat this car as I have many, many issues to be fixed. I checked around and got a price of $650. So I guess I'll just replace them and break them in correctly. BTW the $1200. was for mb stock rotors/brakes. Also, after making several calls, the mechanics felt that the rotors were defective (due to the low milage on the rotors) or that something else was causing the brakes to lock up and suggested that I have MB replace at their cost. It seems many of them have MB's too. SA said he would look into it. Still $650. is not so bad to have a nice riding car. Thanks again.

 

What is the proper way to break in a new set of rotors using existing pads?

 

Let me get the link, one second.

 

http://www.zeckhausen.com/bedding_in_brakes.htm

Caution: When you've just installed new pads/rotors or a big brake kit, the first few applications of the brake pedal will result in almost no braking power. Gently apply the brakes a few times at low speed in order to build up some grip before blasting down the road at high speed. Otherwise, you may be in for a nasty surprise the first time you hit the brakes at 60 mph.

When following these instructions, please avoid doing it in the presence of other vehicles. Breaking in your new pads and rotors is often best done very early in the morning, since other drivers will have no idea what you are up to and will respond in a variety of ways ranging from fear to curiosity to aggression. And an officer of the law will probably not understand when you try to explain why you were driving erratically! Zeckhausen Racing does not endorse speeding on public roads and takes no responsibility for any injuries or tickets you may receive while following these instructions.

From a speed of about 60mph, gently apply the brakes to slow the car down to about 45mph, then accelerate back up to 60mph and repeat. Do this about four or five times to bring the brakes up to operating temperature. This prevents you from thermally shocking the rotors and pads in the next steps.

Make a series of eight near-stops from 60 to about 10 mph. Do it HARD by pressing on the brakes firmly, just shy of locking the wheels or engaging ABS. At the end of each slowdown, immediately accelerate back to 60mph. DO NOT COME TO A COMPLETE STOP! (Note: With less aggressive street pads and/or stock brake calipers, you may need to do this fewer times. If your pedal gets soft or you feel the brakes going away, then you've done enough. Proceed to the next step.)

During this process, you must not come to a complete stop because you will transfer (imprint) pad material onto the hot rotors, which can lead to vibration, uneven braking, and could even ruin the rotors.

Depending on the pads you are using, the brakes may begin to fade slightly after the 7th or 8th near-stop. This fade will stabilize, but not completely go away until the brakes have fully cooled. A bad smell from the brakes, and even some smoke, is normal.

After the 8th near-stop, accelerate back up to speed and drive around for as long as possible without using the brakes. The brakes will need at least 10 minutes to cool down. Obviously, it's OK to use the brakes to avoid an accident, but try to minimize their use until they have cooled.

If club race pads, such as Pagid Orange or Porterfield R4, are being used, add four near-stops from 80 to 10mph. If full race pads, such as Pagid Black, are being used, add four near-stops from 100 to 10 mph.

After the break-in cycle, there should be a blue tint and a light gray film on the rotor face. The blue tint tells you the rotor has reached break-in temperature and the gray film is pad material starting to transfer onto the rotor face. This is what you are looking for. The best braking occurs when there is an even layer of of pad material deposited across the face of the rotors. This minimizes squealing, increases braking torque, and maximizes pad and rotor life.

After the first break in cycle shown above, the brakes may still not be fully broken in. A second bed-in cycle, AFTER the brakes have cooled down fully from the first cycle, may be necessary before the brakes really start to perform well. If you've just installed a big brake kit, the pedal travel may not feel as firm as you expected. After the second cycle, the pedal will become noticeably firmer.

 

Wow! thanks for that. I had no idea. Last brake job I had, I just drove away normally in city traffic from the shop.

 

That might explain the shaking you are getting?

I know when my LS400 got it's rotors machined and new pads, I drove the car hard like the site said.