R1100RT front brake question

[bimmerbeemer]

One of my bikes ('97 R1100RT, 34K miles) has developed a pulsation in the front brake since I installed new EBC pads last year.

I don't have a dial indicator to check rotor run-out but they look o.k. to eye-ball 'em.

 

Since this just came up after replacing the pads, I'm wondering if pad composition could be the cause?

 

TIA,

 

 

[SinNH]

I've run several sets of EBC kevlar, no pulsations.

Even if the rotors were warped a bit, because the are free floating, I don't think you would feel it.

Calipers clean?

Pistons in the calipers free and move easily?

 

[AndyS]

Hi bimmer beemer,

Inspect your discs and pads for glazing.

Removes the pads and give them a going over with some abrasive paper. Likewise your discs need to be thorougly wiped with solvent, then using some emery cloth or wet & dry paper, carefully work it around the inside and outsidefaces of each disc.

Then wipe down with solvent again, remount your pads.

Now test ride the bike. Your bike has 'floating' discs so you shouldn't encounter any disc distortion.

 

Andy

[dirtrider]

Afternoon TIA

 

Yes, pad composition effecting brake pulsation is very possible. In fact that is the usual cause of brake pulsation but the pulsation is usually blamed on warped rotors because that is all people know. Plus they replace the rotor and the problem goes away (must be warped rotors)

 

I’m not sure what EBC pads you used but some pads can deposit a very thin layer of pad material on the rotors (in fact some pad material is designed to work that way). With that type of brake material if you make a hard long stop to super heat the rotors then quickly sit with the brakes clamped onto the hot rotors it adds a build up in that area under the brake pads. It is a from of staining and all but impossible to remove. Not all pad material acts that way and usually aggressive full metallics don’t. But the metallics have other similar issues and that is a rotor staining from a form of very light corrosion (you usually can’t see it with the naked eye) . That comes from parking a bike for a while with damp or wet metallic brake pads against the rotor.

 

You can T-R-Y to use some brake clean and a scotch pad to scrub the rotors, sometimes that helps and other times it doesn’t. Sometimes lightly sanding the rotors with 360 or 400 grit wet and dry can help.

 

Once that staining is set it changes the friction of the rotor in that area and every time the brake pads crosses that area under braking it grabs a little more.

 

Warped rotors as well as rotors with thickness variations usually can be felt in the brake lever as a kicking or lever pulsation. Due to the very thin buildup from rotor staining you usually get the brake pulsation but little or no lever pulsation. Not a 100% but a good way to tell the difference.

 

One thing that I have found that “sometimes” works is to switch to the most aggressive pad you can find then go ride the dickens out of the bike. Whatever you do don’t sit with the brakes clamped on tightly after an aggressive stop form high speeds (in either a bike or a car).

 

[bimmerbeemer]

Thanks to all for the suggestions.

 

I'll try cleaning the pads and rotors to see if it will help.