hman0217

little background...got too busy pre-race and didn't check my disc brake pads. Sure enough, 19 miles into a 41 mile race and those pads are worn to nothing. Worse, yet, the caliper was clinched on the wheel, making the brake slightly engaged for the next 20+ miles. Hardest ride ever!

Anyway, back to the matter at hand...

When I got home (after a few days of recovery) I went to put in new pads and I've read that one can push back on the inside of the caliper body to ease the actuator back out. So I slowly tried to ease them back out. I put the new pads in and I wedged the red plastic thingy that comes with the disc brake pads and hammered on it gently to open up space. That wasn't quite enough so then I inserted the old pad body in there and did the same. I even sanded the new pads slightly to shave off a few mils. I wrestled with it quite a bit and it seemed pretty stubborn.

When all was said and done, the pads are not binding like they were but I still haven't been quite able to open it enough to get totally free movement from the wheel. If I give it a good spin by hand, it will come to stop within 3 rotations. So I can coast on the flats now, but there's definitely some slight resistance that can be felt.

Basically, does anybody have any best practices they wanna share for re-opening the space in a hydraulic disc caliper? The bike is definitely 1000x more rideable than on race day but I'd like to get that last bit of drag out.

It's worth mentioning also that these pads are not OEM. They're cheap metallic pads I found with reasonable amazon reviews. I only mention this incase thickness is infact an issue. (or something else I'm overlooking)

these are TRP Hylex brakes, if it matters

thx

sputniky

Insert screw driver, or Pedro's tire lever, and twist or pry. It should take 30 seconds (28 seconds of which is getting the tool out of the drawer).

shelbyfv

Someone who knows what they are talking about may respond, but absent that I'd try some known-to-be-correct Shimano or TRP pads, just to eliminate that variable.

hman0217

thx. Between the empty calipers or with the pads installed?

Cyclist0108

I do this with the old pads in there, which protects the pistons and more evenly distributes the force. You could do it with the new pads, but if you scratch them you have to live with it. BTW any broad flat-head screwdriver should work fine.

hman0217

well I sure do make life harder than it needs to be sometimes. It worked like a charm. Only thing was it seemed to open on one side and not the other. But loosening the bolts on the caliper, squeezing the brakes and re-tightening centered them nicely and all is well in the world again.

thx
H

fietsbob

I used a plastic pen body to push the pad pistons back , (after removing the pads).. on TRP Hy Rd.

Cyclist0108

One side moves more than the other by design, but both pistons should be flat against the caliper when fully pushed in.

fietsbob

yea, 1 master cylinder, fluid pressure divided to 2 slave cylinders.. 1 may reach the disc before the other

but fluid pressure is equal to both in force application..

Magura's rim brake has a hose from lever master, to 1 side , a connecting hose to the other , same principal..



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