I have a 2002 540 6 spd that I have owned for 3 years. The cars appetite for brake rotors seems to be growing. It had a clean carfax when purchased, and has not been in an accident or had irregular traumas. It does however continue to warp front rotors. In an effort to solve this problem I have replaced the front pads, rotors and calipers, replaced the rear brakes (pads & rotors) as they seemed to be making weak contact, had all front suspension items including bushings checked, but the problem keeps coming back. Now buy the time the oil needs changing the rotors need to be turned. I do not drive the car overly hard ( it was made to be driven - right?) or track it. Any ideas before I take it to the dealer?
I have a '00 540i m-sport 6-speed that gets driven and never had warping rotors. Are all 4 warping, and at the same rate? If so, then it is likely you have been using cheap, lower quality replacement rotors - go to quality parts from Pelican or Bav Auto, or the dealer. Are only the fronts warping? Then it could be driving style or cheap pads/cheap rotors. Other possibilities: wrong torque (too tight) or varying torque (not using a torque wrench), your brake pads were not seated correctly when replaced, or maybe if you have an automatic, and I am sorry to suggest this, but it is possble, do you ride the brake pedal? That's all I can think of, hope these comments were helpful. Let us know what is the resolution. Good luck.
Are you checking the disks for runout, or just changing parts due to vibration in the brakes? if the latter, suggest trying to bed the brake pads before investing in more parts. There is a good set of instructions on how to bed brakes on the zeckhausen racing website. Good luck . . .
I have a experienced the same problem as you have, with my 1998 528i 5 speed. The front end suspension, steering components and tires checked out perfecty. I recently went to high end slotted-cross drilled rotors with ceramic pads and "knock on wood" this seems to have solved the problem.
A lot of pulsating-brake issues are related to the rotor brand. What are you using? If you get them from a BMW dealer, you're getting the best possible but the same brands are also available after-market, too, at sometimes considerable savings even if you're getting a BMW CCA discount off of actual MSRP at your local dealer. But some brands seem to be much better than others. It's a lot like asking folks what brand of oil or tires they use, but my experience is that Balo rotors work great. My experience with stock-style Brembos has not been good, and while I think ATE makes great brakes, their after-market rotors just don't do it for me. I'm a believer in slots helping with braking, but drilling on a street car is just bling, in my opinion. That being said, once you've resorted to turning any rotor, you've probably increased the likelihood of warping simply because there's less meat there to disapate heat. As for the suggestion of pad material; yes, certain pads can leave a residue, especially when parked, that will cause brake pulsation not really related to warped rotors but with the same end result. I've used nothing but low-dust pads in all my BMWs for over thirty years and still recommend them. I'm currently running Repco/Axxis/Whatever-they're-calling-the-company-today pads on my E34 5-Series and they've gone well over 80k since the last rotor replacement. I generally get two pad-changes per rotor if not more (yeah, I hear you. You keep replacing those rotors and I'll keep paying my kids' college tuition!) with no warping issues. My wife's E36 Three is running Zimmerman drilled rotors (previous owner's choice) and Hawk pads (mine) and they've been on their at least 80k if not more. The only BMW in my current stable with pulsating brakes is my E28 535is which got new rotors quite recently but my supplier was out of the Balos I requested and sent Brembos instead. Even some Korean cars come stock with Brembos these days, but I believe Brembo now has Chinese manufacturing facilities to keep up with the demand and cost structure. Check your rotor's country of origin.
Some things to check... if your car has sliding calipers, then make sure the slide mechanisms are clean, or the caliper may not move back to no contact properly and you may have some drag left, and this will keep the rotors from cooling as your always putting a little heat into them. Another way to go if you can't get correction any other way is to upgrade to 1) Better brake cooling ducts. 2) A larger capacity rotor (big brake kit) 3) Other manufacturer rotor replacements for stock brake configurations. Check out Disc Brakes Australia (http://www.dba.com.au/2006/default.asp) they have some venting designs that they claim gets more heat out. Many I know that have used them on thier cars are very happy. The notion that if it says BMW and comes from the factory that it's the best is, um, how do I say this politely, somewhat questionable.... Anyway, these are all good things to think of. Who knows, if you select the correct big brake kit, you can actually lower mass while increasing brake capacity. All it takes is money! Matt
