May 10, 201610 yr Yesterday I had a strange incident while doing a rough track - rear brake got locked up. The disc and the saddle was overheated (it smoked), brake pedal was completely locked and unmovable. Needed some 5-10 minutes to cool down and then worked fine again, pedal started to move and brakes worked again. There were no leaks. Anyone else had this? Oil seems to be quite dark from the master cylinder inspection window. I wonder if I need to overhaul the master cylinder and the caliper hydraulics or just suffice with replacing the DOT4 oil for now?
May 10, 201610 yr I would replace the fluid if its dark, it shouldnt be. If the brake overheats it normally would loose pressure on the pedal, not lock up imo. But the reason for it overheating can be that the piston did not return back good/was stuck.
May 10, 201610 yr I had it once, I didn't have enough play in the pedal, once I slacked it off a little it was fine and has not happened again. I find it is a fine line between too much and not enough free play as I like my braking to occur with as little pedal movement as possible but had to compromise
May 10, 201610 yr Author Cheers guys, I did recently adjusted it for quicker action. Sounds like I need to adjust it off a little.
May 10, 201610 yr Yesterday I had a strange incident while doing a rough track - rear brake got locked up. The disc and the saddle was overheated (it smoked), brake pedal was completely locked and unmovable. Needed some 5-10 minutes to cool down and then worked fine again, pedal started to move and brakes worked again. There were no leaks. Anyone else had this? Oil seems to be quite dark from the master cylinder inspection window. I wonder if I need to overhaul the master cylinder and the caliper hydraulics or just suffice with replacing the DOT4 oil for now? Generally when I see that happen to enduro guys, it's because they're riding the rear brake. Even if you're only slightly dragging it, you're gonna cook it pretty quickly, especially on a trials bike with such a small fluid resevoir. If you're sure you're not dragging the brake, then the brake is dragging on its own, meaning the pistons aren't cleanly retracting and need to be looked at.
May 11, 201610 yr Not enough slack in the pedal , I did the same , only carried on riding after the smoke , the seals melted , fluid came out and then ignited on the disc , all the disc and hub where on fire ,was burning quite well
May 11, 201610 yr Author Not enough slack in the pedal , I did the same , only carried on riding after the smoke , the seals melted , fluid came out and then ignited on the disc , all the disc and hub where on fire ,was burning quite well Wow, that's an incident I reckon I also rode on some time but noticed the bike struggling with power and then stopped, also found the brake disk smoked. I let it cool and all was fine again. I replaced all the fluids. Noticed there was a LOT of crap and sand in the rear master cylinder work area. The rubber design is not the best and sand can get inbetween. Ditto on the front brake master cyl. I cleaned internals and properly greased the rubber cap lips to give it a better seal against the outside crap. On flushing the rear master cylinder: since I don't have the vacuum pump that OSSA recommends I just use the oldschool method - take off the cylinder, place it horizontally with some strap over the rear mudguard and pump it with some sharper tool (i.e. very short screwdriver or a small hex key) that you have enough grabbing force to push the piston in. Do this with one hand while opening the rear airing nipple on the brake caliper with the other hand. Since it's a very small volume master cylinder refill the cylinder every 3-4 pushes, repeat this when you see more clear oil coming out of the nipple, I use transparent hose on the nipple for the best visual inspection. I now also loosened up the rear brake tension adjustment, I think it was at the limit and the reason why it happened. I do love very firm brakes, but now got to get used to riding with softer and less strict rear brake again. Edited May 11, 201610 yr by tsiklonaut
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.