R1100R Brake Issues-Front brake locked

After two months of sitting cranked the R1100R, rode 4.25 miles into town for fuel fill up and front brakes locked solid. Gradually at first, then full lock up. Glad it happened in a 25 mph zone and going straight.

Released some after things cooled off. Cracked open the bleeder vales and all was good. Returned home using the rear brake only. Bullet dodged.

Recent master cylinder rebuild (250 miles ago). I'm thinking should have rebuilt front calipers at same time. Planning to order rebuild kit(s) and pads.

Am I covering all the bases? Non-ABS by the way.

Thanks

All I have read on this makes me ask if the brake lines have been changed- or are they original?
OM

Omega Man said:

All I have read on this makes me ask if the brake lines have been changed- or are they original?
OM

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Replaced with SS lines from Galfer when master cylinder was rebuilt.

If the master cylinder is anything like those on Airheads, it could be that the small return hole in the bottom of the master cylinder is plugged, not letting fluid return back to the reservoir. Might try getting access to the reservoir, find this small hole, and try using something like syringe to suck fluid/debris out near this hole. Just a thought...

20774 said:

If the master cylinder is anything like those on Airheads, it could be that the small return hole in the bottom of the master cylinder is plugged, not letting fluid return back to the reservoir. Might try getting access to the reservoir, find this small hole, and try using something like syringe to suck fluid/debris out near this hole. Just a thought...

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Thanks. Will take a look.

You may have debris from the old brake lines in the caliper that was not flushed out.
Those bits have been known to block fluid return at the caliper banjo stopping fluid return.
Remove all 4 pistons in each caliper and blow out thoroughly. Flush with fresh DOT4.

GSAddict said:

You may have debris from the old brake lines in the caliper that was not flushed out.
Those bits have been known to block fluid return at the caliper banjo stopping fluid return.
Remove all 4 pistons in each caliper and blow out thoroughly. Flush with fresh DOT4.

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Thanks. Will add that to the "to do" list

Follow-up

davidsc said:

Thanks. Will add that to the "to do" list

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Just getting around to this.

Pulled calipers, disassembled, cleaned, and replaced seals and o ring. Honestly they did not look that bad for a 21 year old motorcycle. Reassembled and mounted calipers.

Bled master cylinder per instructions in Clymer manual. No air bubbles.

Refill master cylinder. Connect vacuum bleeder to left caliper. Pull until fluid coming out. Repeat on right side.

Start bleeding per instructions in Clymer manual. Nothing. No pressure build-up at brake lever. Twenty pumps on the lever, crack open the bleeder (either side) and a dribble of brake fluid comes out. No air bubbles. Repeat. Repeat. Repeat. This has occupied the entire afternoon.

Anyone got any ideas on what I'm missing?

Push right and left piston sets all the way home and block from moving out.
Fill a syringe as below and push the fluid up to the master cylinder from each side. (this will not work with speedbleeders)
You have introduced a lot of air to the system by disassembling. (each piston is hollow and holds a lot of air relatively speaking) that air needs to be worked out.
I usually put a little teflon tape on the threads of the bleed nipples so air or fluid does not seep down the threads.


Note: the black thing on the line is simply a shut off valve - not mandatory

Bringing this back up as we experienced another front wheel lockup.

To follow-up, after brakes were bled in March we've been motoring along without issue. About 1700 miles covered without brake problems.

Rode home from E Tennessee yesterday. 145 miles into the return trip on I-26 (141 on the Interstate without using the front brake) peeled off for fuel and a bite. Between fuel, food, and returning to the Interstate used the front brake six times. Got up to speed and it began to drag. By the time I got it stopped, maybe a 1/10th of a mile, the front tire was locked and brake lever rigid. Owing to the first experience released bleeder on each caliper to vent fluid, checked the lever (a bit mushy but I had some pressure), got off the Interstate and rode the remaining 150 miles home without incident. Used the front brake and could not recreate the problem. Hindsight I believe the brake lever was a tad firm at the fuel stop.



So, I'm thinking I start with the master cylinder for disassembly and cleaning. Possibly another rebuild kit. Anything obvious I may be overlooking? Is it possible to overfill the reservoir and cause these symptoms?

Thanks in advance

Check the adjustment of your grub screw. Better to be to loose than too tight.

dieselyoda said:

Check the adjustment of your grub screw. Better to be to loose than too tight.

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I've read of a grub screw that was an update to the right front caliper. Are you referring to that one? My front brakes have bleed screws on both calipers.

The master cylinder has a screw that seems to adjust the stroke of the MC piston. If this the grub screw you describe?

davidsc said:

The master cylinder has a screw that seems to adjust the stroke of the MC piston. If this the grub screw you describe?

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That's the one.

I have had experiences with more than one bike, not just BMW, where the brake fluid heats up enough all the way to the master cylinder and expand in volume enough to make the brakes drag.

Even once, lock up solid after a hard downhill.

dieselyoda said:

That's the one.

I have had experiences with more than one bike, not just BMW, where the brake fluid heats up enough all the way to the master cylinder and expand in volume enough to make the brakes drag.

Even once, lock up solid after a hard downhill.

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!

Thanks.