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#996822 - 09/14/17 12:11 AM Hot front right rotor - Caliper Rebuild?
McDuugle Offline
Newer Member

Registered: 08/11/16
Posts: 35
Loc: DeLand Florida USA
Noticed that my front right rotor gets hot when I ride even if I purposely dont use the front brakes. The left is cold, and the right is hot enough that touching it for more then 5 sec is not possible.

When I spin the wheel freely I can hear drag. I know its probably not the lines being clogged as I just changed them to stainless braided galfer lines about a year ago. Any ideas? If it does come down to a rebuild do any of you have links or contact for cheap rebuild kits. I saw one on ebay for $91.00 both side, that ships from the UK, but that about it so far.
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1998 R1100RT

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#996834 - 09/14/17 01:27 AM Re: Hot front right rotor - Caliper Rebuild? [Re: McDuugle]
MontanaBud Offline
Member

Registered: 06/22/10
Posts: 89
I had the same thing happen recently. I removed the pads, pulled the calipers, carefully forced each of the pistons out slightly, sprayed with brake clean and wiped them down. That fixed it for me. I guess you just have to be careful not to extend the pistons too far.


Edited by MontanaBud (09/14/17 01:30 AM)

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#996842 - 09/14/17 04:01 AM Re: Hot front right rotor - Caliper Rebuild? [Re: McDuugle]
Sam Taylor Offline
Member

Registered: 09/04/01
Posts: 661
Loc: Sonoma, CA, USA
I go a bit further. I force the pistons outa bit and take a toothbrush soaked in soapy water to them, then dry them with either brake cleaner or compressed air or both. Works a treat and has saved me many a rebuild.
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Sam
02r1150RT
Sonoma, CA

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#996883 - 09/14/17 06:55 PM Re: Hot front right rotor - Caliper Rebuild? [Re: Sam Taylor]
Twinsig Offline
Member

Registered: 04/05/12
Posts: 876
Loc: Middle Alabama
Further still, I removed the pistons with compressed air & a few blocks of wood/shims, (it was a real pain) then removed the o-rings cleaned the caliper o ring groves with a steel pick tool, cleaned the pistons with scotch brite pad. Reinstalled the original o rings & those calipers were 214k miles old. But like I said, it was a real pain & time consuming.
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2004 K1200GT


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#996892 - 09/14/17 09:46 PM Re: Hot front right rotor - Caliper Rebuild? [Re: McDuugle]
McDuugle Offline
Newer Member

Registered: 08/11/16
Posts: 35
Loc: DeLand Florida USA
I will give them a good cleaning and see where it gets me.
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1998 R1100RT

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#996929 - 09/15/17 12:43 PM Re: Hot front right rotor - Caliper Rebuild? [Re: McDuugle]
Mike279 Offline
Member

Registered: 05/04/16
Posts: 50
Loc: Syracuse NY
If your brake caliper is sticking, cleaning the outside will do very little. Old brake fluid will break down and form deposits that will need to removed. The thought of buying cheap brake parts is not a good thing either. Brake calipers are very simple in operation and very durable. Each piston has a square cut seal and dust boot. The square cut seal sits in caliper housing and must be able to seal and flex to operate properly. Deposits, corrosion, etc must be cleaned out and the piston free to move in the bore. Then the seal can do it's job and seal the piston so it can move out under pressure and slightly retract as the fluid pressure is relieved. That is why the seal is square cut. First step is to remove, clean and inspect all the parts. If you are not able to do this step, buy a quality part to replace what you have. There is no substitute for good brakes. Mike

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#997267 - 09/19/17 02:19 AM Re: Hot front right rotor - Caliper Rebuild? [Re: McDuugle]
Lowndes Offline
Member

Registered: 05/13/16
Posts: 300
Loc: Roswell, GA
For rebuild parts for Brembo brake calipers, try:

Bevel Heaven

Or:

Munich Motorcycles

The pistons in the calipers are on "dead ends" in the hydraulic passages, unlike most auto calipers. The bleed fitting is connected directly to the brake line beside it. If crud ends up in the passages or pistons, you cannot flush it out by bleeding. Sorry.

I had a similar problem to the OP last year on my '99 R1100S. I disassembled and thoroughly cleaned both front calipers. Lots of crud from decomposing OEM brake lines acted like a check valve inside the calipers. Pictures here:

[url=https://goo.gl/photos/EeCoX13EhGRrfgKh6][/url]

There are warnings in several places to not disassemble (split) the calipers obviously written by the BMW attorneys, not the mechanics. Well, these are MY calipers. They are not much more involved than the oil drain plug, actually. There are four regular bolts and one small "O" ring in a cut-out between the halves. If you can't handle "O" rings, then I too suggest you not disassemble them, but that is the ONLY way to clean and verify they are clean inside. Just only do one caliper at a time. All of my parts, rings, seals, pistons, were pristine (see pics), didn't need anything but DOT4. No problems or leaks since. Rode 800 miles to the Twin Valley Ralley in Meadows of Dan, VA this weekend plus another 4K since the disassembly.
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Old Fart Newbie

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#997337 - 09/19/17 10:52 PM Re: Hot front right rotor - Caliper Rebuild? [Re: MontanaBud]
McDuugle Offline
Newer Member

Registered: 08/11/16
Posts: 35
Loc: DeLand Florida USA
Worked for me! Took the calipers off the rotor, removed the pads, and then just cleaned them very well with break cleaner and a tooth brush. I also pushed some pistons in making the other come out and back and forth to maximize the amount of cleaning I could do. Also used a very fine sand paper and removed rust and gunk from the pin that goes through the pads, less friction when they have to move in or out.

Seams to be great now, both rotors stay the same temp when I ride and I cant see any evidence of drag. Love it.
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1998 R1100RT

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#997409 - 09/20/17 04:11 PM Re: Hot front right rotor - Caliper Rebuild? [Re: McDuugle]
DavidMantle Offline
Member

Registered: 05/15/14
Posts: 59
Loc: Grimsby , Lincolnshire , Engla...
Not a bad idea to change brake fluid while you are at it - just my two pence worth.
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If it ain`t broke don`t fix it cause if you fix it it will soon be broke

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