Will0104 Posted September 5, 2017 Share Posted September 5, 2017 Hey guys,Was cleaning our my front brake caliper piston today. Followed a video on youtube (%29"> ) and first time cleaned it all good and got it back on but missed a clip for holding in a bolt and being a perfectionist decided to redo it all. I noticed there was still a bit of dirt this time so gave ti another clean bringing to piston out further than the previous time. However this time the piston will not go back in (using a g clamp). When i pump out the piston more it will move back in again when i re-clamp it but always stops at the same point (g clamp just becomes too hard to turn). I'm not sure if its me seeing stuff but it always looks that the piston my be ever so slightly slanted further down the one side as well.Any help will be much appreciated,Will Quote Link to comment Share on other sites More sharing options...
Westbeef Posted September 5, 2017 Share Posted September 5, 2017 have you opened the master cylinder? Quote Link to comment Share on other sites More sharing options...
Will0104 Posted September 5, 2017 Author Share Posted September 5, 2017 At first i did forget (on first attempt i didn't and worked fine). second time it got stuck as said and even when i did uncap it still didnt fix it Quote Link to comment Share on other sites More sharing options...
fastbob Posted September 5, 2017 Share Posted September 5, 2017 You could be right, if its slanted only slightly it won't go back in . I wouldn't use a g-clamp , two strong thumbs is usually enough to push a piston in. You could try opening the master cylinder reservoir but these usually have a rubber bellows and a tiny vent to allow expansion and contraction whilst sealing out contamination. Did you completely remove the piston ? I ask because simply pumping it out a bit to clean it doesn't really get to the heart of the matter. Ideally you need to get it right out so that you can remove the seals and clean out the dirt that accumulates behind them. You should take great care to note which way up the seals were so that they go back in the right way round. Not all seals have a right way round but this method eliminates guesswork. There are some good youtube videos on caliper rebuilding that you may find useful. Quote Link to comment Share on other sites More sharing options...
megawatt Posted September 5, 2017 Share Posted September 5, 2017 You should be able to push the piston in by hand, without a G clamp. Quote Link to comment Share on other sites More sharing options...
bud Posted September 6, 2017 Share Posted September 6, 2017 Be careful what you watch on YouTube. I would not use just "any old grease" as some will eat your seals. I would not advise using a clamp either. Would be so easy to get the piston stuck.Sounds like you are not pushing the piston in straight. Quote Link to comment Share on other sites More sharing options...
fastbob Posted September 6, 2017 Share Posted September 6, 2017 Be careful what you watch on YouTube. I would not use just "any old grease" as some will eat your seals. I would not advise using a clamp either. Would be so easy to get the piston stuck.Sounds like you are not pushing the piston in straight. You can use caliper grease or "red rubber grease" but the factory workshop manuals for many bikes specify the use of brake fluid only as an aid to reassembly. This is because some friction is necessary between the seal and piston as the distortion of the seal assists in the return action. If you read my posts near the end of the thread"Brake lever travel" however, you will see that I am contradicting myself. Despite my understanding of the theory of the above, I could only get my rear caliper to stop sticking by applying caliper grease. Sometimes the truth is somewhere in the middle. Quote Link to comment Share on other sites More sharing options...
megawatt Posted September 6, 2017 Share Posted September 6, 2017 Red rubber grease every time, but you need to clean the seal annulus and preferably replace seals with new ones. Quote Link to comment Share on other sites More sharing options...
Will0104 Posted September 7, 2017 Author Share Posted September 7, 2017 okay cheers all. Going to have a play with it this afternoon again. I'm getting a gs500 soon though so if i cant fix it i will just sell as damaged Quote Link to comment Share on other sites More sharing options...
Will0104 Posted September 7, 2017 Author Share Posted September 7, 2017 What are peoples advice with me selling it soon? better just to sell as broken and let someone with more know how fix and use/sell on or attempt to fix myself. With the piston being wonky have i screwed it up? Quote Link to comment Share on other sites More sharing options...
JRH Posted September 7, 2017 Share Posted September 7, 2017 If the piston is just slightly slanted you should be able to twist it level by hand and using brake fluid to lub push it gently back in, again by hand.If you must use a G clamp be very gentle and keep checking to make sure it goes in straight. Hopefully the seals are not damaged.Once back in Bleed the system and check for full operation and the lever does not go all the way back to the bars before going out on the road. I had to do this regularly on the GPS and slow and easy was the key to pushing the pistons back in. Quote Link to comment Share on other sites More sharing options...
Will0104 Posted September 7, 2017 Author Share Posted September 7, 2017 okay thank you for the advice Quote Link to comment Share on other sites More sharing options...
bud Posted September 7, 2017 Share Posted September 7, 2017 Even if you have to buy new seals, it will still be better than selling for parts. You will get much more for a working motorcycle. Quote Link to comment Share on other sites More sharing options...
megawatt Posted September 7, 2017 Share Posted September 7, 2017 What he said. Quote Link to comment Share on other sites More sharing options...
megawatt Posted September 7, 2017 Share Posted September 7, 2017 Where are you? Send me the caliper and master cylinder! Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.