Help- sticking piston in Avid Elxir Brakes

The pads have been dragging on my rear brake. A careful look and I could see that one piston was travelling in and out a shorter distance than the other. My LBS recommended a lube they get from Hope for brakes. Great stuff they said. So I put a drop on. Now the piston doesn’t move at all and pads drag really badly. So I flushed off all the lube with Isopropyl alcohol and lubed the piston with a spot of brake fluid (as I do normally). No joy still no movement from the piston. Anyone fixed an issue like this? If so how?

Remove pistons. Chuck in nearest bin. Fit new pistons/seals. Bleed brake.

Simon, thanks I am hoping there is a less extreme option as I head off for a week’s cycling on Saturday and not sure if I can get the parts in time. Anyone any other suggestions???

I’ve just fixed mine.

Clamp the good piston with adjustable pliers (careful not to damage the surface of the piston – wrap plier jaws with electrical tape).

Lightly lube the sticking piston with a silicon lubricant.

Wait 5 mins for lube to penetrate.

Gently press the brake level till sticking piston works free (or blows your seals!!!!).

Bleed brakes.

If this doesn’t work then as simondbarnes said and

Remove pistons. Chuck in nearest bin. Fit new pistons/seals. Bleed brake.

Good luck 🙂

OK- Well I have fixed the brake and as the solution wasn’t obvious I will leave details here in case anyone else has the same problem.

I read elsewhere that Avid brakes push fluid to the outer piston first. I don’t know if this is true but it made me think about how I could give the inner piston a helping hand as all the drive seemed to be going to my outer piston and the inner wasn’t working (though it did move if I restrained the outer piston with a tyre lever). So I held the outer piston fully into the housing and pumped the inner so that it was about 1.5 mm out from the piston housing. I then carefully slightly off set the caliper (in by 1.5mm) so that when that when I inserted the pads they were centred on the rotor correctly. This all worked as the inner piston travel is now matching the outer. I then spent about 30 mins fine tuning the rotor (at first it was dragging on one pad), eventually I got it to clear both pads so the wheel span free. My Avid brakes are hugely sensitive to caliper position and tiny movement left or right makes all the difference.

You shouldn’t use silicone grease on the pistons. It isn’t stable at disc brake heat temperatures, and will seperate and contaminate.

Look for Castrol Red Rubber Grease.

🙂

See my comments on the other Elixir thread. My LBS have told me they are aware of some Avid calipers rusting internally. Could this be stopping the pistons retreating?

Note: I cannot verify this and don’t know whether this is a genuine problem.

If the piston’s corroding then yes, definately. Probably not if it’s the bores though. Debris from internal corrosion could cause problems too mind.

More likely to be dirt, though. Seals get clogged up and pistons get damaged.

Servicing is easy, could be done in an evening if you have all the bts ready. Replaced my pistons after Kielder 100.

The setup does mean that the outer piston will move first. Unlikely to be a corrosion issue as the piston seemed to be a ceramic material (brittle) and the calipers on mine were spotless.

It might depend on the silicon used. Some silicon compounds are very heat stable 1000°C. Silicon oils are used in (lab) heating systems and resins in high temp paints.

I had a similar problem with my Juicy’s, I’m also going away this weekend!

I got some cotton wool buds, dipped them in brake fluid and cleaned the pistons, lubricating them with the brake fluid. Seem to work a lot better now, probably be back to normal once I get to the WhiteRoom!

@continuity

What kind of temperatures do disk brake calipers reach during use?

Just wondering as i have a small ammount of fairly high temp rated silicone grease and wonder if that will be ok to use instead of buying another tub of lubricant to be stored in the shed.

same issue with my elixir 4s… (actually a juicy caliper, strangely)

I replaced the the pistons after much cursing, greased up with red rubber grease, rebled a few times still got rubbing, tried resetting pads/pistons etc. I’ve knackard my bleed kit piping too as I started to get annoyed with it. I’ve given up with them to be honest, totally sh*t brakes! I will never by avid brakes again. as you say they are so sensitive to caliper position, it really does leave no cleareance either side of the disc. Always have to mess about when you reinstall the wheel aswell… I hate them. Will be ordering the new XTs from rosebikes when back in stock.