brake pulse fixed?

[BMWSTeve]

Three weeks ago I trailered across the state to BMW Grand Rapids for a 12K service. While there I

had them check out the front brake pulse issue. The right front disc was out about .015" while the other spec'd just fine. They road tested it, I did not, too snowy. I hate having to wait till next March or april to ride again. Oh well.

[HairyCannonball]

Mine had a brake vibration issue also, they wound up replacing both rotors. One measured out of tolerance and they relpaced that one first, but the problem was with the rotor that measured in tolerance. Happily with both rotors replaced the brakes are now smooth as a babies heiny. The only thing the dealer and I surmise was that the rotor that was the problem was true, but unevenly heat treated.

 

Tim

[RFW]

Brake rotors do not undergo any special heat treating process, because being a variant of either austenitic or ferritic stainless, they are unhardenable, thus heat treatment is pointless except to anneal the disk before grinding. Ideally, they should be made of cast iron (as in cars), but the rust would be so unsightly, they are made of a barely-stainless alloy (a true stainless disk would give poor braking performance).

 

So the problem you had must have been caused by something else.

 

Bob.

[BMWSTeve]

Brake rotors do not undergo any special heat treating process, because being a variant of either austenitic or ferritic stainless,

 

That may be true, I just wonder about if less than perfect brake pad and rotor break-in caused the warpage. I believe somebody here thought there can be a braking event hard enough that brake material transfers to the rotor from the brake pad.

[skinny]

That may be true, I just wonder about if less than perfect brake pad and rotor break-in caused the warpage. I believe somebody here thought there can be a braking event hard enough that brake material transfers to the rotor from the brake pad.

 

There is always brake material tranfer to the rotor, otherwise your brakes don't work. The problem is un-even transfer which causes the pads to alternately grab and slip. This is usually mis-diagnosed as a bent or warped rotor. My new RT1200 started doing this at about 8000 miles for no apparent reason. The rotors are (by dial indicator) flat and true, but the front brake still vibrates (pulses) so badly that you'd think the front wheel was coming off. I've tried sanding/filing the pad deposits off both rotors and it did help to some extent. Apparently BMW has changed either pad material or rotor material in the new RT's . I never had this problem in 42,000 miles on my previous 1150 RT and I've treated the brakes the same on the new 1200 with far different results...

[Slumgullion]

I had a vibration in my front brake while braking easy. My ST has only 3k on it so I had my dealer check it out and they found that one of the discs were warped. They changed it out Tuesday and the vibration is gone.