troubles with a TRP Hy/Rd disc caliper

[Duck!]

Stop cleaning your rotors.

[familyguy]

They were fine last week. Today, you could've heard me stopping in the driveway from Manly...havent touched them yet. So not a thing changed and yet they are totally ineffectual now. I dont get ir.

[familyguy]

How do you stop the squeal on pads that were quiet the time before unless you clean them?

[queequeg]

How do you stop the squeal on pads that were quiet the time before unless you clean them?

I am yet to have any squeal with my TRP brakes, either in dry or wet. I kind of miss the high pitched noise that my BB7's used to make under even the lightest of braking!

[familyguy]

At this stage, you'd be welcome to take any and all disc brakes off my hands...grrr.

I went full leak check yesterday:



Seals are all good, no leaks. Need to refill and bleed and check the power levels again. Something I must be missing........

[queequeg]

I spoke too soon. Riding home on Thursday, my rear brake felt significantly degraded from the morning ride. Was scratching my head trying to figure out the issue. It was difficult to see the pads and rotor with everything fitted, but as my front brake was fine I just rode on home. It was blowing such a gale that brakes were the least of my worries anyway.

So, over the weekend I put the bike up on the stand, and the issue is one of the pistons was not moving. It was stuck all the way in and no amount of actuating was hlping. HOwever, I found that if I put the spreader against the good piston and then actuated the arm, it got enough pressure to pop the piston out a bit. Sadly, I overestimated how far to let it comes out, and the whole piston came out, leaking mineral oil. That gave the piston a good lubrication and it now seems to move in about ok.

I found a YouTube video on the TRP site about keeping the pistons lubricated to stop them from sticking. So, I have a bleed kit on the way so I can service the caliper. Hopefully it's just a lubrication issue and I'll be back in business.

[ValleyForge]

I found a YouTube video on the TRP site about keeping the pistons lubricated to stop them from sticking. So, I have a bleed kit on the way so I can service the caliper. Hopefully it's just a lubrication issue and I'll be back in business.

Silicone grease - as recommended by Hope. Found it at a boat chandlers. Never had a worry since.

[ValleyForge]

How do you stop the squeal on pads that were quiet the time before unless you clean them?

Earplugs.

But seriously, I have found that more often than not the squeal settles down over time. I now only go "full-OCD clean" when I've given up waiting.

[Duck!]

Brake pads can become glazed - essentially the pad surface has been melted, rehardened and polished from high surface temperature, often but not exclusively from extended low-load application of the brakes. Periodically sand the glazed surface off the pads, but do not use any solvents.

Similarly for rotors. Optimal brake function relies on a layer of pad material being embedded onto the rotor surfaces. They're often noisy until they're bedded in. Cleaning with solvent of any kind removes the embedded pad material, and usually exacerbates any noise rather than curing it. So as I said further up the page, don't clean your rotors, unless you are absolutely sure there is oil contamination on the surface. Then make sure you properly bed them in again.

[familyguy]

Which I get, but also confuses the issue, for me. The brakes were bedded in. Worked great. Quiet. Powerful enough. They have not been used in two weeks, and were quiet when last used. Now they're banshees. I'll give the pad sanding a go though, won't touch the rotors.

Then maybe I'll revisit the HyRd and see if they might actually like to develop some stopping power, perhaps.

[queequeg]

I found a YouTube video on the TRP site about keeping the pistons lubricated to stop them from sticking. So, I have a bleed kit on the way so I can service the caliper. Hopefully it's just a lubrication issue and I'll be back in business.

Silicone grease - as recommended by Hope. Found it at a boat chandlers. Never had a worry since.

Interestingly, the TRP video says to use nothing but the mineral oil to avoid contamination of the fluid and breakdown of the seals. WIll see how I go. After moving the piston a few times it seems to be fine, but because I lost some oil when the piston came out, it needs a top up. Bleed kit should be here soon. Weather tomorrow in Sydney is looking like it will be a moth's rainfall in one day, so maybe it's a blessing in disguise that my commuter bike is off the road.

[queequeg]

So, got my bleed kit(s) today. lubricated the sides of the sticky piston, did the bleed to refill and get rid of all the air.

Piston still sticky. It will only move the piston on one side, unless you hold a little bit of pressure on the other piston, then it will start to move. This is of course totally useless this is by design, so when the first piston contacts the brake rotor, it will be enough to get the other piston to come out.
I don't recall this happening when I first installed them.

Anyway, I can't pull the caliper apart to inspect the seals because I don't have the required Torx security screwdriver...so that's another expense to go get one of those. The Spyre's are beginning to look atttractive, as I don't have time for this mucking about on my commuter bike.

[ValleyForge]

as I don't have time for this mucking about on my commuter bike.

The enemy of good is better. If one piston lags but the brakes work OK...

Some of these things you just don't need to "Busta Gonad" over.

[queequeg]

as I don't have time for this mucking about on my commuter bike.

The enemy of good is better. If one piston lags but the brakes work OK...

Some of these things you just don't need to "Busta Gonad" over.

The rear brake was providing almost no braking force because the piston that was working could not push the rotor over far enough to get any force applied against the opposing rotor. I pulled the trigger on a pair of Spyre calipers, which were $74 each (including a rotor). Other option was buying another HY/RD caliper, but given these brakes have only had about 3 months of actual usage since being fitted, a stuck piston is not a sign of longenivty. As terrible as the BB7 brakes were from a "chunkiness" and noise point of view, they went 50,000km without a single issue.
If the Spyres are crap with the SRAM levers, I have the trigger ready to go on ripping out the SRAM Rival gear and converting the bike to Tiagra 4700 with SLR-EV Cable Pull. That also lets me go up to a 36 cassette. If the Spyres are still rubbish after that, Shimano CX77 brakes are the final option before making the reulcant choice to go back to BB7s.

[queequeg]

My TRP Spyre Brakes arrived. $74 each with a spare 160mm Rotor.

Fitting was simple, and I didn't even have to bend my mudguard stays into new shapes to clear the calipers, as they are similar profile to the HY/RD brakes. I was able to adjust the pads inwards sufficiently that even with the SRAM levers I have almost instant engagement of the brakes without having to pull the levers half way to the bars. That means they'll be perfect if/when I switch to Shimano, but so far it looks like I can save that expense for now.

I still have the HY/RD on the front at the moment as there is nothing wrong with it, and I may tinker with the HY/RD rear brake and see if I can get it working smoothly again, then either keep as a spare or get rid of it. The main thing I have discovered is that if your main commuter bike has hydro brakes, you better have all the spares and maintenance kits handy before you have an issue. I had to wait 4 days for my bleed kit, and when that didn't solve my issues I had to wait another week for the new calipers, so I have been unable (well, unwilling) to ride to work with only the front brake working (nervous about getting a stuck piston there too, then having no brakes!)

[familyguy]

The solution is n+1.

But yes, I've temporarily abandoned my disc bike until the break and I can do some proper work on it.

[queequeg]

The solution is n+1.

But yes, I've temporarily abandoned my disc bike until the break and I can do some proper work on it.

I have 3 other bikes, but none of them are setup to take panniers, and I hate commuting with a backpack. My gravel bike is still getting the dynamo lights waited up, which I’ll be doing over Christmas, and my Steel roadie is on the Kickr...which just leaves my R5.

Anyway, it’s all sorted now. I have bleed kits at hand, plus a spare mechanical caliper. Took me 2 minutes to swap the caliper over, and only had to trim about 5mm off the last segment of cable outer to compensate for the different position.

[queequeg]

SO, my TRP HY/RD adventures continued. My front brake got a stuck piston as well this week, which was not so fun when going down a hill suddently to find that I had lost most of my braking power.

Rather than muck about with mineral oil trying to unstick it (I never could get the rear brake piston to work properly, even after lubrication and total replacement of mineral oil with the bleed kit), I simply installed the other TRP Spyre caliper. Now I have full mechanical disc brakes again, without needing any dodgy fixes to make them work with SRAM Levers. All is good in the world again. Not sure if stuck pistons is something that happens on all Hyro brakes, or whether it is just the TRP HY/RD calipers. Not sure I even care enough to find out now. Too much stuffing about when the bike they are on is my main commuter bike, which must stay working all the time.

[Duck!]

Not sure if stuck pistons is something that happens on all Hyro brakes, or whether it is just the TRP HY/RD calipers.

Sticky pistons can afflict any hydro brake caliper. From professional observation, it is entirely random, not specific to or more prevalent in certain model calipers, nor will every caliper in any given model suffer the affliction.

[queequeg]

Not sure if stuck pistons is something that happens on all Hyro brakes, or whether it is just the TRP HY/RD calipers.

Sticky pistons can afflict any hydro brake caliper. From professional observation, it is entirely random, not specific to or more prevalent in certain model calipers, nor will every caliper in any given model suffer the affliction.

I might have a look at it on the weekend and see if lubricating it with some mineral oil will get it unstuck. I tried unsucessfully on the rear caliper to get it working again. There was some suggestions about replacing the seals, but since the calipers are less than 6 months old and have barely done 1000km of riding, having to replace the seals this soon does not give me much confidence in their long term viability.

If I put a small amount of pressure on the good piston and then actuate the arm, the stuck piston will happily move out. Take away that pressure and it won't budge. To open the caliper to service it, I need to buy a Torx Security Wrench, and that also means another bleed kit to be sacrificed putting it all back together, and that is before trying to source new seals (if that is indeed the issue). It seems crazy doing that when I bought the Spyre calipers for $75 (even came with a spare rotor).

Maybe a better option is to just take both calipers up to the local bike shop and let them deal with it? What would your advice be?

Paul