warped brake rotors

[stx133]

Have done nearly 130,000 k in 3 years, mostly hwy miles. keep ending up with warped rotors and brake shuddder. Had the brake calipers overhauled early on because they were not releasing properly (warped rotors x1) new disks, replaced the front end - ball joints, control arms etc... warped rotors x2 disks machined, warped rotors x3 replaced disks under warranty, warped rotors x4 machined and now warped again.

This is starting to create a lack of satisfaction inf the driving experience (ie: give me the sh1ts)

The replacement disks were supposedly OEM. could i get 2 faulty sets?

Before i replace the disks again (need suggestion on what to get, happy to air freight in from o/s) need to ensure that there is no other problem. How do i check the brake release, put the fron end on a jack and spin the wheel, pump the brakes and go again???

Suggestions on proof of test and new rotors will be appreciated.

thanks

[Jehu]

You bought rotors from a BMW Dealership each time?

Do you feel the steering wheel buck whenever you brake ,at whatever speed and thru the whole event;from first contact thru stop or for instance if you are on the highway if you plant your foot firmly , braking hard , will it be smooth but a more gradual braking yields the shudder?

I put new slotted Brembo's on the front about 70k miles ago with slotted Zimmerman's on the rear ( only because they didn't have Brembo's in stock for the rear) and I am under highway braking at certain points with a gradual brake getting the steering wheel shudder. If i plant my foot on the pedal , not locking it up just a firm press its smooth. I haven't inspected my control arm bushings but the other points where fault bushings reveal themselves aren't there ( shudder on acceleration thru 40-50 mph)

I'd be in an asylum if I'd been going thru what you describe.. Hope you get it sorted out without going broke or insane.

[Russell]

Having what appears to be a similar type of problem. Replaced brakes with ATE stock style rotors and Raybestos QS ceramic pads. After 25,000 miles turned rotors to eliminate shudder when braking. Now back again after 15,000 more. Pads look worn only a little. Heard stock style Brembo rotors are better.

I am going to have my steering and suspension checked to see if there is component wear next week. My car seems to wander. BTW, struts and upppr control armss have been replaced.

[stx133]

Have only paid for one set of rotors, the replacement was under 'warranty'. My mechanic looks after me pretty well. He has made his best attempt to sort out brakes, now i am looking for more help.

The shudder through the wheel is with anything other than FIRM (read aggressive) braking. It is 'available' throughout the whole range of speed, 20 - 100

[Barney Paull-Edwards]

Thats almost beyond coincidence. I`de check either the bearings or the face that the disc lands on for run-out. Oem discs have done me proud,Zimermans were on the front for track days and the ring but ate pads and actually did no better if I cool standard discs.

[Tiger]

Do you wash your car/wheels after driving without cooling down? Splashing cold water on brake rotors while hot will warp it. Most people don't realize this.

Thrust arm bushing... what do you have there? M5?

Do you have brake ducts?

Do you torque your wheel bolts? Impact gun will warp your brake rotors in no time.

[Tiger]

They don't have tight tolerance like BMW does... American cars has much looser tolerance that even if it is slightly warped... doesn't matter as their wheel bearings gives them room to wiggle.

German cars do not have any wiggle room.

[glen-sj]

Did you break in your brake and rotors properly? I to had the same problem with premature warping of rotors, until I found out the need to break in the brakes after installation. Here's how to -
"Bedding In" Your New Brakes
After you have completed your work, it is a good idea to perform a process called "bedding in" on the brakes. This process will mate the new pads to the rotors. A transfer of material occurs between the pad and rotor surfaces, thus conditioning the rotors micro-finish. This pad/rotor break-in serves to stress-relieve the rotors and creates a compatible pad/rotor package.

Accelerate to about 40 mph. Bring the vehicle to nearly a complete stop. Remove your foot from the brake pedal, and accelerate again to 40 mph. Apply moderate brake pressure again, bringing the vehicle to nearly a complete stop. Repeat this 12 to 30 times. Drive about 1/4-mile between each braking. To prevent localized hot spots on the rotor, do not sit with the brake pedal depressed immediately following one of these deceleration runs.

[Russell]

Tiger,
In my case I think the monkey who put on my tires has warped my rotors. I do not think they followed my instructions to use a torque wrench at about 75 lbs.

I also do not wash my wheels when rotors are hot. No quick rinse at the coin DIY car wash on the way home for me.

Funny thing is my wifes Explorer has never had this kind of issue.

[Ross]

If the calipers aren't hanging up, the rear brakes are doing their job and you are bedding the new brakes in properly the rotors may be at fault again. When remachining a rotor the "high" spots are removed to make it run true, this also leaves thinner areas less able to dissipate heat and the whole nasty cycle starts over at an accelerated rate.
My real suspicion is you have loose suspension components that are allowing things to squirm around under braking as the weight transfers. The thrust arm bushings are notorious on these cars.
Another check of this would be to find a fast ,long sweeping turn such a highway on ramp, preferrably with bumps(a good excuse to come to Chicago).
If you hustle the car a bit and hit bumps while in a turn and the front shakes like mad that is another sign of worn suspension.
I wish I had a nickle for every brake rotor sold to correct suspension problems. Good luck.

[bubba966]

You shouldn't be warping the rotors on a 540. Something's not right. Do you 'ride the brake' (leave your foot sitting/resting on the pedal) at all while driving?

BMW rotors don't usually last very long if they get machined as they're not meant to be machined. After machining they do get thinner and will be more likely to warp.

Are your caliper pins lubricated/greased? BMW caliper pins are supposed to NOT be lubricated. Lubricating them leads them to gum up after a while and then they don't move freely which will cause the caliper to either not fully retract the pads or apply them un-evenly causing them to not work right which could lead to overheating things and warping the rotors.

I'd say you should clean your caliper pins, get a good set of new rotors & pads, and send them (rotors & pads) to One Cryo for a proper Cryo treatment. www.onecryo.com

Then when you get the rotors & pads back from Cryo make sure that the hub surface is clean and free from rust and other debris. Properly torque the wheels on (to 88 lb-ft), and then properly bed in your new brakes.

[Tiger]

There is something wrong... which is why you are warping your brake rotors.

[stx133]

The front end was completely re-built 12 months ago, no signs of 'wiggle'. i did bed the new rotors in with the seccond set to ensure this was not the cause.

[Ross]

They don't have tight tolerance like BMW does... American cars has much looser tolerance that even if it is slightly warped... doesn't matter as their wheel bearings gives them room to wiggle.

German cars do not have any wiggle room.
Okay

[632 Regal]

I had an interesting experience, ordered real Balo rotors for the front to see if the old el cheapo rotors were warped and they were because its good again.

The cheapo rotors are cast "crooked" where the vent holes are at you can see that one side of the surface is thicker and the opposite side is thinner. Man I would get a nasty violent shake when these things got hot.

The Balos are cast perfectly in comparison, nice and even all around. Bed in rotors??? I have Raybestos QS which require no bed in.


The front end was completely re-built 12 months ago, no signs of 'wiggle'. i did bed the new rotors in with the seccond set to ensure this was not the cause.

[stx133]

[QUOTE=bubba966]You shouldn't be warping the rotors on a 540. Something's not right. Do you 'ride the brake' (leave your foot sitting/resting on the pedal) at all while driving?



Are your caliper pins lubricated/greased? BMW caliper pins are supposed to NOT be lubricated. Lubricating them leads them to gum up after a while and then they don't move freely which will cause the caliper to either not fully retract the pads or apply them un-evenly causing them to not work right which could lead to overheating things and warping the rotors.

QUOTE]
I do not 'ride' the brakes, is there a procedure somewhere for cleaning the caliper pins, pics?
How much movement do you expect when the calipers 'fully retract'?

Thanks.