| Author | Message | ||
     Gjwinaus |
XB9R – 2003 – 10,00miles ( 16,000 Km) I had ridden about 80 mile ( 130 Km ) to a race event, left it parked all day and on my return trip after about 30 miles ( 50 Km ) I stopped for a wiz (rural roads), then back up to 60 mph ( 100 kph ) and within 5 miles the front brake applied itself, with no input from me. When I came to a stop the front brake was applied so hard that I could not roll it forward or back. The lever was very hard in its forward position, I then cracked open the brake bleeder, after a little spurt of brake fluid the front brake released and the lever went to its normal movement again. The front brake system has never been dis-assembled, It was the factory fluid but 4 years old I dis-assembled the front caliper and hand piece totally, inspected all parts including all the rubber part with a 10 X magnifying glass and all parts were as they left the factory. I them reassembled the front brake system with the original parts using new dot 4 fluid and new brake pads, having first dis-assembled the front caliper and hand piece and carefully laying them out so they would be reassembled exactly as they can out of the hand piece and caliper. I also blow out the brake hose. After fastidious bleeding and checks for function and leaks I went riding, ( Bleeding was by filling the hand piece reservoir and opening and closing the bleeder as I pumped the lever) ) I applied the front brakes multiple times to bed the pads and within 3 miles the problem had returned, I cracked the bleeder again and returned home. As I was returning home I tentatively applied the brakes several times and the brakes performed normally. Incidentally, I am now waiting for new parts to rebuild the hand piece and caliper and do the job properly. The 64 dollar question is “can anyone tell me what caused the problem” | ||
| Gjwinaus |
Bump | ||
| Nillaice |
i'd guess it's the relief port on the master cylinder is clogged or sticks closed. that's my 0.02 glad to hear you didn't get hurt, and you bike is ... functional. (you could use the rear brake) to answer your question; i'd say not changing you brake fluid for the last 4 years is what caused it. i'll accept cash, money order or pay pal for those 64 dollars, thank you | ||
| Gjwinaus |
I found it myself, some times ago I had broken a brake lever and it was “order it and wait” but right next door was a Kawasaki dealer with a lever to fit a 900 Kwaka that was “identical”. Unfortunately it would not let the hand piece piston come all the way back and occasionally it would seal the brake system and maybe the heat pressurized the fluid and locked the brakes on. I don’t why it did it only twice in months of riding. Machined the pusher part of the lever to uncover the port and all fixed. I used Henrik’s syringe method in the KV / Brakes section to determine that the return port was covered and Nillaice, thanks for the input, I think I was in the shed discovering the problem as you were typing the above post. Thanks anyway. | ||
| Gjwinaus |
Just for the record the first time it happened I was traveling 60mph and the front brake applied itself and after I realized the front brake was coming on, I declutched and rolled to a moderate stop, nothing frightening, The second time it happened, I was stopped at traffic lights and I nearly lost the front end as the light went green but traffic slowly eased their way past me, I released the bleeder and rode it home and no drama there either. There is probably a lesson in there somewhere. | ||
| Bluzm2 |
Graeme, you are one lucky dude! You beat me to the punch on the diagnosis. I was going to ask if you had changed brake levers. One of the things that was discovered right after the XB's were introduced was the you cannot use an XB lever on an old Tuber framer. The results are the same as you experience even though you have an XB. The bleed back hole was not uncovered at full release to let the pressure bleed off. This causes the pads to drag on the rotor which in turn caused heat buildup. This causes the brake fluid to get hot and expand and caust the dragging to increase. Classic positive feedback loop. Eventually your front brake locks. This is a good lesson for everyone. Make damn sure you are using the correct components! Really glad you didn't get hurt. Brad | ||
| Gjwinaus |
Thanks Brad,I sounds like it could have been worse. | ||
| Chopperdave |
It was for me, highside, broken pelvis, hematoma, big ass bruise...  pics on another thread: http://www.badweatherbikers.com/cgibin/discus/show.cgi?tpc=4062&post=1111334#POST1111334 (Message edited by chopperdave on May 18, 2008) |
