hgas Posted February 7, 2015 Report Share Posted February 7, 2015 My ajp front brake seems to be sticking on, got a good lever with loads of free play and the bite is excellent but after using the brake it sticks on /drags , I think the Pistons are sticking so what is the best way of solving this do I split the kaliper or do I take pads out ,pump the brake so the Pistons come all the way out and grease them or wd40 etc?? Cheers in advance Quote Link to comment Share on other sites More sharing options...
copemech Posted February 7, 2015 Report Share Posted February 7, 2015 Dirt/ corrosion behind the boot on the master cylinder can also cause the brake to hold pressure as the piston cannot return fully regardless of lever free play. Cracking the line or bleeder will relieve the pressure if that is the case. Never use mineral oil or grease on brake pistons or seals as the rubber is different and not compatible and will quickly ruin. Quote Link to comment Share on other sites More sharing options...
2stroke4stroke Posted February 7, 2015 Report Share Posted February 7, 2015 Push the pistons out a bit (caliper off the bike), clean the surface then spray with silicon lube. Work pistons in and out a bit and they should free off. Give a final spray of the silcon, remove the surplus then replace pads and fit to bike. The silicon lubes the seals and prevents dirt getting a hold on the metal bits. Quote Link to comment Share on other sites More sharing options...
wakka Posted February 7, 2015 Report Share Posted February 7, 2015 Take out the seal and turn it around so the sharp edge face is out.. i use only seal rubber lube and use only a small amount, I have a brake fluid tester. i cheek my fluid every 6mths and it turns the light red when there is moisture in the master cylinder. this also makes the pistons stick. Cheers Wakka Quote Link to comment Share on other sites More sharing options...
dadof2 Posted February 7, 2015 Report Share Posted February 7, 2015 Dirt and or corrosion behind the seals in the calliper will cause this. Quote Link to comment Share on other sites More sharing options...
hgas Posted February 8, 2015 Author Report Share Posted February 8, 2015 Think I've solved the problem I split the kaliper and gave the Pistons a good clean put it all back together but now for the life of me I can't get it to bleed , I've got a bit of a lever but it goes all the way back to the handle bar before it bites , how do people normally bleed them ? Thanks for all the help so far bin brilliant Quote Link to comment Share on other sites More sharing options...
2stroke4stroke Posted February 8, 2015 Report Share Posted February 8, 2015 If you have pushed the pistons all the way in you may have difficulty getting a bleed. But try putting a plastic pipe on the bleed nipple and tapping the caliper to persuade the air out. Or you could try forcing fluid through from the caliper with a syringe. Quote Link to comment Share on other sites More sharing options...
steve_earle Posted February 8, 2015 Report Share Posted February 8, 2015 Dirt and or corrosion behind the seals in the calliper will cause this. 99% this is always the case, It looks clean at 1st glance but get a pick with a hook on the end and scrape the part of the lip you can't see and you will be suprised what comes out! Always put the seals back in the same way round as they came out, They are slightly tapered. Quote Link to comment Share on other sites More sharing options...
aussiechris Posted February 9, 2015 Report Share Posted February 9, 2015 The best way I have found to get the caliper bled is to start with the pistons removed, then holding the caliper half at about 45° with the drillings (bleed or feed holes) at the top, pour as much brake fluid into the cavity without spilling it. That should half fill the caliper. Then, maintaining the same angle, push the piston back in all the way. As the piston goes in, it should expel the air out of the bleed or feed hole along with some fluid. Now you should have the piston all the way into the caliper with just fluid behind it. Bolt the caliper halves together and refit on the bike then bleed as usual. Hope you get it sorted. Chris. Quote Link to comment Share on other sites More sharing options...
hgas Posted February 10, 2015 Author Report Share Posted February 10, 2015 Thanks for that Chris il give that a go ?, and thanks to everyone else aswell much appreciated Quote Link to comment Share on other sites More sharing options...
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