greg watts Posted October 23, 2012 Report Share Posted October 23, 2012 I use a Beta Rev 3 for technical trail riding in the alps. On longer descents , no matter how brake-friendly I ride (low gear, really slow, as much engine braking as I can find) the brakes get really hot and start to bind on. Anyone got any ideas on what I can do to improve the situation. I am using good quality Galfer pads, but was wondering if I could use dot 5.1 fluid perhaps or find other ways to dissipate heat better? Quote Link to comment Share on other sites More sharing options...
feetupfun Posted October 23, 2012 Report Share Posted October 23, 2012 The fluid only dissipates a miniscule amount of heat compared to the discs and calipers. There may be higher boiling point fluids available, but even if you raise the boiling point, the discs will just get hotter and melt the pad surface (losing their frictional properties) and maybe also catch fire. Bigger disc brakes as fitted to enduro bikes would work well for the sort of riding you do. Quote Link to comment Share on other sites More sharing options...
pindie Posted October 23, 2012 Report Share Posted October 23, 2012 When hot and binding try loosening your master cylinder lid. Remove the rubber diaphragm and mop up and spillage. Now put it all back together. You just have to much fluid for it to expand. If this does not work then try the higher boiling point fluid but check it is suitable for your braking system. Quote Link to comment Share on other sites More sharing options...
pindie Posted October 23, 2012 Report Share Posted October 23, 2012 That should say "mop up any expanded fluid spillage". Quote Link to comment Share on other sites More sharing options...
longlegscanbeuseful Posted October 23, 2012 Report Share Posted October 23, 2012 I had a similar problem caused by the previous owner adjusting the lever too much. Make sure you have a few mm's of play before the lever engages the pusher. I guess this stopped the brakes releasing all the way and allowing for further expansion when hot. Quote Link to comment Share on other sites More sharing options...
nelly1 Posted October 23, 2012 Report Share Posted October 23, 2012 I had a similar problem caused by the previous owner adjusting the lever too much. Make sure you have a few mm's of play before the lever engages the pusher. I guess this stopped the brakes releasing all the way and allowing for further expansion when hot. just had this myself easy fix Quote Link to comment Share on other sites More sharing options...
neilh Posted October 23, 2012 Report Share Posted October 23, 2012 yep, another vote for the lever adjustment here. i had my levers set up for a miniscule amount of play as id didnt like the thought of a sloppy lever. (im borderline obsessive compulsive lol) i had the exact same problem as you are experiencing. slackened levers off, now its fine. Quote Link to comment Share on other sites More sharing options...
pindie Posted October 26, 2012 Report Share Posted October 26, 2012 Very good point. There has to be play at the lever plunger. Quote Link to comment Share on other sites More sharing options...
dan williams Posted October 30, 2012 Report Share Posted October 30, 2012 There is a hole in the cylinder that the plunger must return past. The brakes are an open system. When they are off the plunger in the master cylinder is supposed to come all the way back into a rest position that opens the hole so there is a complete path from the caliper up to the reservoir. That way any expansion of the fluid caused by heating can’t build up pressure in the system and the next application of the brake starts from the same zero pressure point regardless of fluid temperature. Three things usually bung this up. The first is adjusting the lever so it partially pushes the plunger in part of the way as a starting position. This is common with riders who want their brakes to engage further from the bars. The problem is the plunger never uncovers the hole into the reservoir and as the fluid heats up from normal braking and expands the only place it can go is the caliper which forces the pads to drag on the rotor generating more heat and more drag eventually locking up the brake system. The other thing I have seen is the plunger return spring can be damaged by a fall that slams the brake lever on. This deforms the spring so even with the proper lever adjustment the plunger never returns to the proper rest position opening up the hole to the master cylinder. The third is debris blocking the reservoir hole. So yeah start with the easiest thing first and make sure the lever adjustment allows the plunger to come all the way back in the master cylinder to be stopped by the circlip that keeps it in the bore. Quote Link to comment Share on other sites More sharing options...
greg watts Posted October 30, 2012 Author Report Share Posted October 30, 2012 Thanks guys. Front brake certainly could be backed off a bit so I'll try that. The rear though seems to have a fair amount of play in the lever before it does anything and is set very high, so I'm not sure that has scope to adjust any further and that is causing the same issues (getting hot and binding), but I will investigate/adjust and let you know if there are any further issues. Appreciate the assistance from you all :-). Quote Link to comment Share on other sites More sharing options...
greg watts Posted November 1, 2012 Author Report Share Posted November 1, 2012 Checked my brake adjustments and they seem fine. The plunger is coming all the way out with no problems. I'll take a look at the fluid levels and inside the master cylinder. Quote Link to comment Share on other sites More sharing options...
outlaw dave Posted November 3, 2012 Report Share Posted November 3, 2012 The caliper seals may be binding due to a build up of dirt - worth checking Quote Link to comment Share on other sites More sharing options...
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