slogger Posted February 21, 2010 Report Share Posted February 21, 2010 Since getting back into trials I have been practicing regularly and have attempted three events. Unfortunately two out of the three (today being one of them) resulted in a mechanical retirement. The first one was last year on a 94 Techno which I bought to get back into it and today on a 2004 Rev 3 which up until today had performed without fault. Both retirements were rear brake calipers sticking on. Not fun on a snowy day. Using the rear brake on some tight camber turns (after about 10 sections), I could not workout why I kept losing the rear? On checking, the brake was not releasing cleanly. So my question is really about general maintainance for brakes? I was always taught to leave hydraulic brakes alone unless they are sticking as playing around with the seals and pistons causes more damage than good. I think I have probably been mis-advised and really need to understand a typical maintainance routine for hydraulic brakes. I dont want any more retirements........I want to enjoy my Sundays getting muddy, tired and generally making a fool of myself! Rob Quote Link to comment Share on other sites More sharing options...
shercoman2k8 Posted February 21, 2010 Report Share Posted February 21, 2010 Make sure there is some free play in the lever, or else the fluid in the caliper heats up, expands, and locks your brake on until it cools down. Sure someone will expand on this for me. If not, I'll check back and do it when I'm slightly more awake Quote Link to comment Share on other sites More sharing options...
stork955 Posted February 21, 2010 Report Share Posted February 21, 2010 Gday, as Shercoman says. It also probably needs a fluid change as well, this should be done every 2 years maximum anyway. Good luck with that, search the Beta forums for more info, there is lots of it. Cheers, Stork Quote Link to comment Share on other sites More sharing options...
jamersby Posted February 21, 2010 Report Share Posted February 21, 2010 I had this problem just recently and I had changed the brake fluid, in my case two of the four pistons in the caliper were not returning at all, I split the caliper on mine and took the pistons out, I made sure all the fluid ports were clear, I carefully took out the o rings in the caliper and washed them suprising how much grime came off, cleaned all inside the caliper especially where the o rings fit, I lightly sanded the pistons to remove any other grime lubricated all the parts and re assembled it, fitted the caliper bled it been no problem since. I hope this helps in some way, I put my sticking brakes down to the grime around the pistons. Quote Link to comment Share on other sites More sharing options...
slogger Posted February 22, 2010 Author Report Share Posted February 22, 2010 Guys, thanks for the prompt replies. Took the caliper off once I got home and the pistons are not returning so a full strip down in in order. Was just wondering, if you normally do this on failure only or is it common practice to give the calipers a service (ie strip them down) ewvery 4-5 events as a matter of course ? Rob Quote Link to comment Share on other sites More sharing options...
stork955 Posted February 22, 2010 Report Share Posted February 22, 2010 Gday, theres no way I would want to strip a rear Trials caliper every 5 events, even if I was paid. Bleeding them is a nightmare... Regular fluid changes (annually is how frequently I do mine) is the best preventative measure. It probably also pays to not leave them wet after washing etc. A good run up the driveway dragging them to get a bit of warmth in may help a lot long term. Use rubber grease to lubricate everything on reassembly. Available from any automotive parts place - note - this is different to "normal" grease and designed to be used in braking systems on rubber components. Cheers, Stork Quote Link to comment Share on other sites More sharing options...
jamersby Posted February 22, 2010 Report Share Posted February 22, 2010 I agree with Stork955 I wouldn't want to do this as a maintenance thing I would only do it when the brakes fail, a couple of little tips I found useful was when you disconnect the brake fluid hose tie it up as high as you can it may stop the brake fluid draining out saving you alot of bleeding ( and swearing ) it worked on mine. The other thing I found useful should you have a piston that's fully pushed home, or tight in the caliper, is to insert an expanding rawlbolt that just fits inside the piston I use a 12mm rawlbolt, tighten the rawlbolt up with a spanner until it grips the piston then with the spanner you should be able to turn, twist,pull and push the piston with little effort and with no damage. Quote Link to comment Share on other sites More sharing options...
john.b Posted February 22, 2010 Report Share Posted February 22, 2010 I agree with Stork955 I wouldn't want to do this as a maintenance thing I would only do it when the brakes fail, a couple of little tips I found useful was when you disconnect the brake fluid hose tie it up as high as you can it may stop the brake fluid draining out saving you alot of bleeding ( and swearing ) it worked on mine.The other thing I found useful should you have a piston that's fully pushed home, or tight in the caliper, is to insert an expanding rawlbolt that just fits inside the piston I use a 12mm rawlbolt, tighten the rawlbolt up with a spanner until it grips the piston then with the spanner you should be able to turn, twist,pull and push the piston with little effort and with no damage. What a good idea about using a rawlbolt to withdraw the piston, I've messed on with airlines in the past to try to blow them out. Will try that next time, thanks for the tip. Quote Link to comment Share on other sites More sharing options...
tltel Posted February 22, 2010 Report Share Posted February 22, 2010 Hi Slogger I had a similar problem of the rear brake locking on my sons gas gas, Not sure why but it seems its not uncommon and managed to borrow a 10mm spanner off another rider that had also had this problem. Since then we always carry a spanner and just release the bleed nipple to reduce pressure.(although only had to do it one more time) This was on a bike that had a new master cylinder and caliper seals and fliud level was correct, My assumption was that maybe my son tends to ride the back brake which overheats the fluid. Its worth putting a spanner in your pocket next time out it might save your ride. TLTEL Quote Link to comment Share on other sites More sharing options...
slogger Posted February 28, 2010 Author Report Share Posted February 28, 2010 Cheers TLTEL, will bear that in mind, although had the callipers apart today. A very sorry state of affairs. Neither set of pistons wanting to give much even with an airline. Thinks its going to be the rawbolt tip next................. Quote Link to comment Share on other sites More sharing options...
slogger Posted March 7, 2010 Author Report Share Posted March 7, 2010 (edited) At last they are striped! Tried the rawbolt but could not get a good enough purchase. In the end it was a very patient 2 hrs with a compressor popping one out at a time and them g clamping to ones that had freed up (one 2 were out I found that a old file fitted great across the faces and held the free ones in just the right place to pop the others out). Now time to order a refurb kit. Does anyone have some top tips and avoids for the perfect rebuild ??????? I noticed a few in this posting but I always seem to get a slight lip on the new seal no matter how persistent I am ?????? Edited March 7, 2010 by slogger Quote Link to comment Share on other sites More sharing options...
stork955 Posted March 7, 2010 Report Share Posted March 7, 2010 Gday, clean all parts with Soap and water only. Dry everything well with air, or warmth from a hairdryer etc. Polish the pistons and bores with fine polish and wash in soap and water after. Make sure the grooves for the caliper seals are free and clear of all rubbish. Use Rubber Grease to lubricate everything on re-assembly. Double and Triple check that there is free travel at the brake pedal before attempting to bleed. It will not bleed unless there is. Check the forum here for further bleeding tips. Good Luck, Cheers, Stork Quote Link to comment Share on other sites More sharing options...
slogger Posted March 7, 2010 Author Report Share Posted March 7, 2010 Stork, cheers for that. A stupid question.....do you apply the rubber grease to the seal prior to seating in the groove or just to the outside lip and piston when seating the piston. Someone previously told me not to grease the seals as you get a "hydraulic" effect (grease in the groove causing the seal to sit out)??????? Quote Link to comment Share on other sites More sharing options...
stork955 Posted March 8, 2010 Report Share Posted March 8, 2010 Gday, I just fit the seal first and then grease it, the piston, and around the outside of the caliper bore to help stop crap getting in around the piston. (More usually around the boot area that most bikes still use, but ours don't. ) Piston should be a nice slide in fit after passing the seal. Cheers, Stork Quote Link to comment Share on other sites More sharing options...
slogger Posted March 10, 2010 Author Report Share Posted March 10, 2010 Stork, cheers for that. Parts have arrived so will have a bash over the weekend. Rob Quote Link to comment Share on other sites More sharing options...
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