[bman5150]

I bought my car with 34k miles on the odometer. It had warped rotors (vibration felt thru steering wheel when braking at speeds more than 45 mph) so I took it to the dealer and they replaced my front pads and rotors (around 40,000 miles when I got this service.) I now have 57,000 miles, and the rotors are warped again. I do not auto cross and really don't even drive the car that hard. What gives?

I am wondering if it's bad LCA bushings or suspension related....something that is allowing excess play and over time is causing the brake rotor runout to be out of spec.

Any thoughts?

[feuer]

E9x doesn't really suffer from warped rotors. Neither does worn out LCA cause much brake vibration like on previous 3-series like e46 and e36. E9x is different design.

I would do this:
Replace the bushings on the calipers guide pins and scuff down the rotor surface from any pad material build up. Then clean the hub from all derbies and rust to make sure the rotor is sitter flush. Also inspect the bearing for dead play and whether the hubs are straight. When mounting the wheels torque them properly.

Hope that helps.

[Meeni]

Warped rotors is very rare. What iis common iis suspension geometry problems or a wheel out of true causing uneven pad deposit, which iis a temporary ailment that can be fixed once the root cause has been addressed.

[techwhiz]

Rotors not warped.
Either suspension components worn or deposits on the rotors from the pads.
http://stoptech.com/technical-suppor...nd-other-myths

[bman5150]

Thanks for your replies. Here's a funny thing - for the past two days, I haven't felt nearly as much of the vibration in the steering wheel when I'm braking. You guys might be right about the pad deposits. I'll get some brake cleaner and spray the rotors and see if that helps. I've never heard of folks having brake rotor warping problems with the 3 series, which is why I was surprised.

[Stream]

Had this problem too.

Aug 2013: New rotor (ATE) + new pads (EBC red)
Apr 2014: Slight shaking while braking when brakes are cold and hard shaking after warming up. Resurfaced rotors and problem solved. Then after one month replaced front "upper" arm bushing (Meyle HD).
Apr 2015: Same story - hard shaking after warmin up. Replace rotor (Zimmermann), pads (OEM), left front wheel bearing. Waiting for next april

Originally Posted by bman5150

Thanks for your replies. Here's a funny thing - for the past two days, I haven't felt nearly as much of the vibration in the steering wheel when I'm braking. You guys might be right about the pad deposits. I'll get some brake cleaner and spray the rotors and see if that helps. I've never heard of folks having brake rotor warping problems with the 3 series, which is why I was surprised.

Spraying brake cleaner on rotors isn't going to remove pad deposits. You'll be wasting your time. With the wheel already off though, you might as well just try actually fixing the problem by:
1. Running an aggressive/abrasive race compound pad up to temp for a while in order to scrub the face of the rotors themselves.
2. Have the rotors turned (poor decision).
3. Replace the rotors.

[ajaye]

Further to feuer's suggestions, buy a few of these.

http://www.amazon.com/gp/product/B00..._detailpages01

Hit the hub face including the centric ring, the rotor mounting surface face front and back, and the wheel mounting face including the center bore, make those bitches shine. With the 3M pads after a northeast winter I probably spent 20 minutes or so per axle after a few seconds with brass wire knocking off the big scaly/loose crap. Then use a new pad and hit both friction surface sides of each rotor and clean with brake cleaner until you can wipe the rotor with a clean towel and brake fluid and aren't picking up any more dirt/grease/grime. Then go run a proper bed in (2 heat cycles at least with proper cooling before parking up after each).

If you do all this and still end up with the vibration, it ain't the rotors.

[bman5150]

What is the proper torque specs for the wheel lugs? Just asking in case someone knows off top of their head. I can also look it up in the manual. Thx!

[ajaye]

Originally Posted by bman5150

What is the proper torque specs for the wheel lugs? Just asking in case someone knows off top of their head. I can also look it up in the manual. Thx!

pretty sure its 89 ft lbs. In that neighborhood should be fine, the important part is that you use the same value for all the lugs.

[feuer]

Originally Posted by ajaye

Further to feuer's suggestions, buy a few of these.
http://www.amazon.com/gp/product/B00..._detailpages01

this is designed for rotors:
http://www.amazon.com/Brush-Research.../dp/B007SOW0WC

Originally Posted by bman5150

What is the proper torque specs for the wheel lugs? Just asking in case someone knows off top of their head. I can also look it up in the manual. Thx!

German standard, good and tight! I do 100lbs

[88atlas07]

I have Zimmerman blanks with red stuff pads and mine warp after the first hard break from 140+mph. its pretty ridiculoushow quickly these things warp. Ive learned to live with the wheel vibration after going through 3 fronts and have checked everything there is to check and the brakes just get too hot.

Torqued wheels, and even tried track pads at one point and still warped the front

[SGe92is]

The rotors don't warp. There are plenty of articles online that will help diagnose your issues.

http://www.brakeandfrontend.com/warped-rotors-myth/

Usually it is pad transfer/deposit that can be removed. I would have to re-bed my pads on one of my older cars with a Brembo BBK frequently due to pad transfer build up.

[Meeni]

Originally Posted by 88atlas07

I have Zimmerman blanks with red stuff pads and mine warp after the first hard break from 140+mph. its pretty ridiculoushow quickly these things warp. Ive learned to live with the wheel vibration after going through 3 fronts and have checked everything there is to check and the brakes just get too hot.

Torqued wheels, and even tried track pads at one point and still warped the front

This is not warped rotors, this is improper bedding procedure. The problem is not with the parts or the car, it's between the seat and the wheel

As for the Op, I would not recommend changing the rotors before you actually understand what is the root cause. It will return if you do not fix the suspension/tire/wheel issue that makes it happen.

[88atlas07]

Originally Posted by Meeni

This is not warped rotors, this is improper bedding procedure. The problem is not with the parts or the car, it's between the seat and the wheel

It could be, but Ive tried both ways of bedding in brakes. The 500-1000 miles easy driving method, and the 50-10 hard braking method. I dont think people realize how much heat is created when you do max braking at triple digit speeds. The car really needs a BBK

Ive had one pair of rotors turned and they were indeed warped, not baked on pad material.

[Stream]

Originally Posted by 88atlas07

It could be, but Ive tried both ways of bedding in brakes. The 500-1000 miles easy driving method, and the 50-10 hard braking method. I dont think people realize how much heat is created when you do max braking at triple digit speeds. The car really needs a BBK

Ive had one pair of rotors turned and they were indeed warped, not baked on pad material.

Totally agree.

[CALWATERBOY]

Originally Posted by bman5150

I bought my car with 34k miles on the odometer. It had warped rotors (vibration felt thru steering wheel when braking at speeds more than 45 mph) so I took it to the dealer and they replaced my front pads and rotors (around 40,000 miles when I got this service.) I now have 57,000 miles, and the rotors are warped again. I do not auto cross and really don't even drive the car that hard. What gives?

I am wondering if it's bad LCA bushings or suspension related....something that is allowing excess play and over time is causing the brake rotor runout to be out of spec.

Any thoughts?

Aha! Well now. Like the people say, warped rotors - rare indeed.

But rotor deposits aren't, and can be caused by:

• Bad bushing[s]
• Low transmission fluid [leakage]
• Improper or varying wheel lug nut torque

Quick fix: Rub swept area with emery cloth, she be sa-mooth awhile....

[techwhiz]

Read the link in an earlier post.
There is almost no chance that anyone has warped rotors after street driving.

You remove deposits, brake more aggressively.
A couple of times from 60-70 on an off ramps hould clean them up.

[DoubleParked]

Originally Posted by techwhiz

http://stoptech.com/technical-suppor...nd-other-myths

^ This.

"Cast iron is an alloy of iron and silicon in solution interspersed with particles of carbon. At elevated temperatures, inclusions of carbides begin to form in the matrix. In the case of the brake disk, any uneven deposits - standing proud of the disc surface - become hotter than the surrounding metal. Every time that the leading edge of one of the deposits rotates into contact with the pad, the local temperature increases. When this local temperature reaches around 1200 or 1300 degrees F. the cast iron under the deposit begins to transform into cementite."

"...if the grinding does not remove all of the cementite inclusions, as the disc wears the hard cementite will stand proud of the relatively soft disc and the thermal spiral starts over again."

If your rotors have areas of deep cementite (which is invisible), replacing the rotors is your only option.

[feuer]

Originally Posted by Meeni

This is not warped rotors, this is improper bedding procedure. The problem is not with the parts or the car, it's between the seat and the wheel

That is not nice Meeni.

Originally Posted by 88atlas07

It could be, but Ive tried both ways of bedding in brakes. The 500-1000 miles easy driving method, and the 50-10 hard braking method. I dont think people realize how much heat is created when you do max braking at triple digit speeds. The car really needs a BBK

Ive had one pair of rotors turned and they were indeed warped, not baked on pad material.

Yes, correct, it happens but other vehicle components and parts from the brake assembly contributed to it. It was not solely due to heat. The caliper bushings are slope as well as all suspension bushings because they are design to work with heavy run flat tires.
You will not have repeat problem if you address all of those issues even if you don't by BBK

Originally Posted by CALWATERBOY

Aha! Well now. Like the people say, warped rotors - rare indeed.

But rotor deposits aren't, and can be caused by:

• Bad bushing[s]
• Low transmission fluid [leakage]
• Improper or varying wheel lug nut torque

Quick fix: Rub swept area with emery cloth, she be sa-mooth awhile....

Can you please explain further low transmission fluid little more in depth. Is my first time hearing about it. Thank you!

Originally Posted by techwhiz

Read the link in an earlier post.
There is almost no chance that anyone has warped rotors after street driving.

You remove deposits, brake more aggressively.
A couple of times from 60-70 on an off ramps hould clean them up.

Yes, almost 0% chance for street driving. If only pad build up is the cause few hard brakes followed by a proper cool down will take care of it.

[Stream]

You remove deposits, brake more aggressively.
A couple of times from 60-70 on an off ramps hould clean them up.

It didnd't work for me. Twice! Harder you brake - harder steering wheel shakes. Maybe it's pad deposits, but you can't remove them with rebedding or agressive braking.

I think OP has the same problem.

[CALWATERBOY]

Originally Posted by feuer

Can you please explain further low transmission fluid little more in depth. Is my first time hearing about it. Thank you!

Experience - can't say why it happens, as a technical explanation. But feels just like an overheated rotor! Did not do when cold.