Brake rotors warping problem

[georgeb]

Hey folks,

I am on my second set of rotors on my 02 R1150RT. The first developed the familiar warped pulsing feel following a spirited trip on Palomar Mtn. Now on this second set, I may have warped on a trip accross the mtns near Big Bear.

 

A search of the forum did not reveal any answers so i don't think this is a common problem. Am I just braking too hard/late? I have not had problems if I just kept a steady speed between corners so I didn't need to brake into corners.

 

These things are expensive!

 

George

[philbytx]

Have the discs been checked for run out (to verify they are warped)or is it more a "seat of the pants" feel (so to speak) for the pulsation?

 

Try this one.....get some DENATURED alcohol and a clean rag. Fold the rag, soak it in the DENATUREd alcohol, hold it in your hand and fold your hand around the discs and rotate the disc through 360 degrees a couple of times. Do the same thing with the clean half of the rag on the other disc and then go out and try your brakes. Brake easily at first then to a couple of hard stops then see if the "pulsation" has stopped.

 

Had a similar deal with my 03 RT and turned out it was some form of contamination on a disk.

[T__]

Hey folks,

I am on my second set of rotors on my 02 R1150RT. The first developed the familiar warped pulsing feel following a spirited trip on Palomar Mtn. Now on this second set, I may have warped on a trip accross the mtns near Big Bear.

 

A search of the forum did not reveal any answers so i don't think this is a common problem. Am I just braking too hard/late? I have not had problems if I just kept a steady speed between corners so I didn't need to brake into corners.

 

These things are expensive!

 

George

 

 

George, are you SURE they are warped.. Even the first set? Put a dial indicator on them, & check for run out..

 

You can get a fairly pronounced pulsation due to rotor metal contamination or even etching.. Feels just like warped rotors as you get a pulsation under braking as the contaminated rotor area passes the brake pads..

 

I have had similar problems on my Ducati if I ride it extremely hard with extreme braking then stopping at a stop light or stop sign with the front brakes held on.. The extra hot rotors allows the brake pad material or possibly the pad material binder to contaminate the rotor in that one spot & etch it enough to put a spot on the rotor with a different coefficient of friction so from then on I get a brake pulsation as the pads cross that etched section under braking..

 

The cure for me was to use brake clean & scotch pad to clean the rotors (light pulsation problem)… It got so bad that I even had to remove the rotors & place them in my lathe then use a DA sander on them while rotating slowly..

 

It took a while for me to figure out what was happening & a few checks with a dial indicator (no warping but still had a brake pulsation).. The real cure has been to not sit with the front brakes on at a stand still with extremely hot rotors.. I either hold it at a stop after a hard run using the rear brake (only) ,, or ride a while with no front braking to cool the rotors before holding the bike sitting still with the front brake.. It seems that some of the higher metallic content pads are not as bad at hot rotor contamination (or they are just more aggressive & scour the rotor surface clean after the contamination) but then you can get oxidation etching if sitting for long periods with damp brakes..

 

You might also make sure your rotors are still somewhat floating & not binding as that can cause you problems also..

 

Twisty

 

 

[georgeb]

I am familiar with the contamination of the rotor from pad leeching. I had the previous set checked at the dealer and they determined the warpage. Could have only test ridden it however... I have noticed that when the brakes get hotter, it sometimes seems to smooth out.

 

The pulsing I am getting shakes the windshield when braking from higher speed. I'll try the brake cleaner and scotch pad tonight.

 

Q: how do you sit at a light w/only the rear brake on a linked system?

 

Thanks for the prompt input.

George

[T__]

Q: how do you sit at a light w/only the rear brake on a linked system?

 

Thanks for the prompt input.

George

 

George, my Ducati doesn’t have linked brakes & with the short wheel base I seldom use much rear brake when hot dogging it..

 

As far as sitting still with very hot linked brakes? You either need to ride it out a little to allow air cooling or if that isn’t possible leave some room in front & roll the bike slightly so the pads see many places on the hot rotor (those brake rotors don’t cool with a darn while sitting still with no air flow) .. When I exit a freeway in my car at very high speeds then very high G braking I never sit with the brakes locked without moving slightly as I wait for a stop sign or light.. Stock automotive brake pads transfer pretty bad & 400° & a good high speed (90-100 mph) stop can easily yield 500°-600°c..

 

You might also look into a higher performance brake pad for your BMW as stock pads will probably begin to transfer friction material to the rotor in a very uneven buildup at between 300°-400°c & if you are really pushing that bike you might be seeing front brake temps approaching 600+°c..

 

Twisty

 

[georgeb]

I do have an IR thermometer. Ill have to try a couple stops, but in the twisties hard corner braking temps are cumulative.

[T__]

George, might not get a good reading on those somewhat shinny rotors.. My heat gun is less than accurate on light colored metal objects.. Might try some temp recording tape on a non swept rotor surface or back of a brake pad.. That will show max accumulated temps also..

 

I just saw your above—

 

I have noticed that when the brakes get hotter, it sometimes seems to smooth out.

 

That is how my Ducati acted with the pad transfer problem.. If I got them hot enough the friction equalized & made it better until the brakes cooled again.. Usually warped rotors get worse with high heat & expansion..

 

Twisty

 

[georgeb]

Very cool...

Thanks for the responses. I cleaned the rotors this evening with brake cleaner and a rag. Couldn't find my steel wool or emery cloth but will try that next if needed. I was able to "move" the rotors on the pins so they don't seem to be binding. Tomorrow morning will tell.

[Jeron]

Twisty's first post is spot on.

 

Read this:

http://www.stoptech.com/tech_info/wp_warped_brakedisk.shtml

 

Use Garnet Sandpaper to buff off pad deposits.

[georgeb]

That may actually have been the article or one similar that i read when i upgraded my truck brakes. Thanks for reminding me of that...

[georgeb]

So it looks like EBC has their more aggressive HH pads available for the RT.

Front Pads: FA355HH*

Front Rotors: MD620LS$a Left side, MD620RS$a Right side

 

Rear Pads: FA363HH

Rear Rotor: MD653$a

 

Anbody have recommendations or comments on these for more aggressive replacements? Rotors were just looked at since if I need replacement, they are about $100.00 cheaper than factory.

 

Thanks,

George

[T__]

So it looks like EBC has their more aggressive HH pads available for the RT.

Front Pads: FA355HH*

Front Rotors: MD620LS$a Left side, MD620RS$a Right side

 

Rear Pads: FA363HH

Rear Rotor: MD653$a

 

Anbody have recommendations or comments on these for more aggressive replacements? Rotors were just looked at since if I need replacement, they are about $100.00 cheaper than factory.

 

Thanks,

George

 

 

George, I see you have an 02 RT.. That particular bike already has a very aggressive rear brake.. When I had my 02 RT I actually went the other way & installed the earlier 95 R bike organic rear brake pads to tame the rear brake down little.. I can’t imagine anybody would want a more aggressive rear brake on the IABS equipped 02 RT..

 

Twisty

 

[smiller]

On my 1100RT I detected a definite improvement in rear brake power when going from the EBC 'black' organic pads to the semi-metallic HH compound (Twisty's probably accurate comments about the desirability of this notwithstanding.) The HH also seems to be a little harder on the rotor FWIW. I haven't done the front yet but if I can feel the difference on the rear then I anticipate an even more noticeable improvement on the front, albeit at the possible cost of some rotor life.

[Jeron]

The rotors were so much cheaper than the pads I opted for the EBC regular pads rather than the HH to hopefully extend rotor life.

[georgeb]

So I got the pads on... well almost. The right side front caliper grub screw / post that holds the pads in, torx head stipped out and I had to drill it out. I picked up a replacement at Long Beach BMW and will stop at sears for a Metric tap and die set (have a full std set... go figure) to clean out the threads and finish installing the right side pads. I have already sanded clean the front and rear rotors. I'll likely ride it tonight if it dries up out here and tomorrow to bed in the new pads. If I still have the pulsing in the pads due to cementite, I will replace the rotors with the EBC replacements for about $150.00 each ($100.00 cheaper than stock).

more news to come.