More back brake woes!

White Noise · Mr Dudwee Joined: 17 Dec 2004 Karma :

If any of you don't know my back brake has been binding, taking the calpers of i could see that the pistons where very dirty and the dust seals where riped to shreads, so i figured this was the problem! therefore i dismattled it all and gave everything a good clean, put new seals in and tonight i have just tried to reassemble them, got everything together o.k but one of the pistons had to be put into the calipers with the aid of G clamps, once it was all together i bleed the system and tested the brakes, it was then that i noticed that the piston that was an arse to put in was sticking and not moving in line with the other piston, so same problem happening! of binding, i would like to know if anyone has any fixes, is it that the piston is not lubricated enough or the piston has become warped.
any ideas will be well recieved
Cheers
WN
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Buy my wife: 96' Yam XJ600s (Diversion)
Wing Commander White Noise - SE Clique
Riding Tip #86: See God, then back off a bit: Problem is i haven't seen god yet, just a close up of tarmac on revett straight

Scotsman37 · World Chat Champion Joined: 17 Aug 2004 Karma :

Did you actually clean the caliper with actual brake cleaner? Was the sides of the piston free of pitting but the innards of where the piston slides in/out also free of pitting ?

Usually if you smear the sides of the pistons with brake fluid that usually helps it to slip in/out.

You shouldn't have had to put the piston back in with a G-clamp if the caliper was disconnected from the brake line or the master cylinder was open as you should have been able to put in simply by hand. So it could possibly be warped, but unlikely not unless something drastic happened to it to get warped.

You could simply buy a new set of pistons for the caliper.

MattEMulsion · World Chat Champion Joined: 29 Aug 2004 Karma :

Take the piston back out and look for any signs of scraping/burrs on the piston. There is obviously something not right with it. Unless you can get this piston moving freely of its own accord in the caliper then you p**sing in the wind. If all else fails you may have to source a 'new' caliper.
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Yamaha YZF-R6

White Noise · Mr Dudwee Joined: 17 Dec 2004 Karma :

Scotsman37 · World Chat Champion Joined: 17 Aug 2004 Karma :

Here you go they sell them for your bike and lots of other items too;

https://shop.wemoto.com/index.dyn

White Noise · Mr Dudwee Joined: 17 Dec 2004 Karma :

Cheers scotsman,
i have come across wemoto before, they seem pretty good but never ordered anything from them, anyway i think i may have got to the bottom of things, i took the pistons and the seals out again when out of the calipers the seals slip over the piston fairly easily, therefore i reconed that the seal seats aren't deep enough, cleared more crap out of the seal seats with a .5 mm allen key, put the seals back in and lubed them and the piston went in with a lot less resistance than it did before! going to try and fit them again in the morning, hope it works this time!
Cheers for all your help will keep you posted
WN
____________________
Buy my wife: 96' Yam XJ600s (Diversion)
Wing Commander White Noise - SE Clique
Riding Tip #86: See God, then back off a bit: Problem is i haven't seen god yet, just a close up of tarmac on revett straight

ZRX61 · Victor Meldrew Joined: 05 Nov 2003 Karma :

White Noise · Mr Dudwee Joined: 17 Dec 2004 Karma :

Guest · Brolly Dolly Joined: 22 Apr 2004 Karma :

Had a similar thing with my back caliper. I stripped it down, removed the pistons and seals and washed it all out in diluted Jizer. Then popped it in the oven at 120 degrees for 20 minutes to get rid of any moisture. This also seemed to crystalise any corrosion left in the seal grooves and it scraped out nice and easy with my thumbnail.

I also cleaned the piston with just my thumbnail, wouldn't use anything coarser Wink