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The levers on my Guide RS's are pulling back much further before the pads contact the disc. If I pump them they sort themselves out and they feel solid and not at all spongy. I've read about this issue which suggests they need bleeding or the pistons in the caliper sticking.
They have been bled a few times using the correct kit but this made no improvement.
The pistons and seals in the calipers have also been changed.
Also tried advancing the pads with the wheel out but this just caused them to rub after pumping the lever.
Even tried pumping the lever and using a cable tie to hold it on over night.
Any other ideas?
You'll know if the piston is sticking as it won't work - they get slow to return, then jam. Leave the bike in the sun for a bit today. If the levers jam, then it's the piston. I've changed both lever pistons. No issues since.
If you are pumping then working, sounds like air somewhere. Epic have some very good instructions that are fool proof.
Out of interest, how easy it to change the piston ? Need to do mine, they don’t like the warm weather 😡
This is a guide to a fix, if your putting new pistons in don't bother with the sanding.
Heat doesn't make any difference so I'll try bleeding them again.
Sometimes pulling the lever back to the bar and holding it there overnight with a tywrap helps.
and using a cable tie to hold it on over night.
I used to leave it strapped up overnight with the front end elevated and then bleed the lever only, I was always surprised how much air came out after I had done what I thought was good caliper and lever bleed!
I think I'll try just bleeding the lever next. I'm guessing if there was air in the caliper it would feel spongy which it doesn't.
Still no luck here. Bled the lever again. When it bites it feels solid. Not spongy at all. The problem is the bite point is much closer to the bar than the front brake.
Tried taking the caliper off and pulling the lever to advance the pads which works for about 5 seconds.
Any other ideas? Worth taking the lever apart?
Just a thread hyjack, changing the piston is easy, but getting the circlip out is tricky. I bent mine getting it out, but straigntened it no issues. Use the washer to help hold the piston in as you push the circlip back in, by pushing the washer to one side in the circlip's recess.
I had/have the same issue with mine. I recently saw a thread suggesting to clamp the lever overnight against the bars (or as close as possible), which you have also tried. After I tried this the lever feels amazing! I also did a bleed. However I haven't had a chance to ride it yet, so not sure if that trick solved the problem or not. I also recently rebuilt the entire brake set. I think for me the seals were not letting the piston advance enough (and stay advanced) as the pads wore down. Might be worth whipping the calipers open and cleaning them up?
**edit - just noticed you have done the caliper already. Might be worth giving the lever end a go?
I had a lot of issues with my front RS - bled it so many times and in the end got a replacement.
Now I am still having issues - replaced front disc too and I just don't seem to get a lot of bite up front compared to the back. I bedded them in and they both have same throw. Maybe the front slightly less, but marginal.
Maybe I just need to just keep braking more and see if it improves!!
I think I've solved it now. Did a lever bleed yesterday and got some air out. Though I think air was getting in somewhere as the bubbles never stopped! Checked all the bolts and they were tight so no idea where air was getting in. Left the syringe in for about 10 mins and bubbles kept coming out. After that I took the caliper off the frame and advance the pads then pushed them back. Now it feels balanced with the from brake now.
Short ride this morning in the sun and no issues at all.
I think I might try a bleed on the front I guess. I have decent lever throw and it’s not to the bars but just lack of bite.