I've been running SRAM rival brakes for several yrs on a gravel bike and have never had any issues before. I usually bleed them a couple of times a yr to keep them nice and firm but recently the front lever got slowly longer and then was hitting the bar with no pressure on the pads. And then a week later this happened on the rear. I then bled both brakes and all seemed fine with the bleed block in place, ie. nice and firm, but then when the bleed block is removed and you pump the lever to bring the pistons out to the pads, they only move out about 0.5mm ie. so no pressure on the pads, and this is the same for both F & R?
It's as if there isn't enough fluid in the system, but I've followed the SRAM instructions as I've always done. Maybe the master seals have failed in the levers? Spoke to SRAM and they don't have any new ideas and just say take them to a dealer.
Anyone got any ideas?
Cheers
Not really.
But the lever adjustment on my SRAM Rival brakes does quite often "go off", so the lever comes closer to the bars, and then I have to wind out the little hex-grub screw thing underneath the lever.
Have you followed the SRAM pad advancement procedure as outlined in the manual? Put the wider side of the pad spacer tool in the calliper with no pads in and pump out the pistons. Repeat a couple of times etc following the procedure. Don’t be tempted to apply any lubricant/DOT fluid to the pistons themselves though…
Sounds a bit like when the MTB master cylinder pistons sieze up.
Thanks for the feedback.... Yes followed the SRAM bleeding procedure. With the bleed block removed and no pads fitted, normally every lever pump would move the pistons out a few mm until the pistons make contact with the pads and rotor, but every pump only moves the pistons out about 0.5mm and then when the lever is released the pistons move back 0.5mm! So total piston travel is only about 0.5mm and that's it? With the bleed block back in place they grip fine, the lever feels as it should and is nice and firm, so it not an air thing, more lack of fluid?
I would try and hold one piston in place while allowing the other to extend. R3pro do a tool that helps with this and I think another company do them too, mentioned on here somewhere but I can’t remember where… R3pro might not do a Rival one … You may be able to use a tyre lever carefully…
Sounds like a lack of fluid or air. The bit I usually forget is after closing the caliper port to flick the brake lever a few times whilst pulling on the brake lever syringe. Then give a little but of pressure before you clamp the syringe off.
Thanks again.... Pretty sure that's what I've done, but will give it another go and let you know...
Regarding holding one piston in while pumping the lever, I've tried that and free piston only moves out about 1mm and then retracts again as the lever is released, so no better really? Cheers
In case of interest:
