Go Back  Bike Forums > Bike Forums > Bicycle Mechanics
Reload this Page >

Unbinding hydraulic calipers - best practices

Bicycle Mechanics Broken bottom bracket? Tacoed wheel? If you're having problems with your bicycle, or just need help fixing a flat, drop in here for the latest on bicycle mechanics & bicycle maintenance.

Unbinding hydraulic calipers - best practices

Old 05-12-19, 03:18 PM
  #1  
hman0217
Member
Thread Starter
 
hman0217's Avatar
 
Join Date: Jul 2016
Location: Brooklyn, NY
Posts: 29

Bikes: Surly LHT, Lynskey Cooper cx, Specialized Stumpjumper 26er, Jamis Dragonslayer

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 17 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Unbinding hydraulic calipers - best practices

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
hman0217 is offline  
Old 05-12-19, 03:31 PM
  #2  
sputniky
Banned.
 
Join Date: Apr 2019
Posts: 82
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 46 Post(s)
Likes: 0
Liked 7 Times in 5 Posts
Originally Posted by hman0217 View Post
Basically, does anybody have any best practices they wanna share for re-opening the space in a hydraulic disc caliper?
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).

sputniky is offline  
Old 05-12-19, 04:22 PM
  #3  
shelbyfv
Senior Member
 
shelbyfv's Avatar
 
Join Date: Jun 2007
Posts: 5,116
Mentioned: 17 Post(s)
Tagged: 0 Thread(s)
Quoted: 1050 Post(s)
Liked 64 Times in 47 Posts
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.
shelbyfv is offline  
Old 05-12-19, 05:39 PM
  #4  
hman0217
Member
Thread Starter
 
hman0217's Avatar
 
Join Date: Jul 2016
Location: Brooklyn, NY
Posts: 29

Bikes: Surly LHT, Lynskey Cooper cx, Specialized Stumpjumper 26er, Jamis Dragonslayer

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 17 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by sputniky View Post
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).

thx. Between the empty calipers or with the pads installed?
hman0217 is offline  
Old 05-12-19, 05:47 PM
  #5  
wgscott
Occam's Rotor
 
wgscott's Avatar
 
Join Date: Jul 2013
Location: The Timbers of Fennario (CL77)
Posts: 4,787

Bikes: Steel

Mentioned: 61 Post(s)
Tagged: 0 Thread(s)
Quoted: 2366 Post(s)
Liked 152 Times in 90 Posts
Originally Posted by sputniky View Post
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).

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.
wgscott is offline  
Old 05-12-19, 07:01 PM
  #6  
hman0217
Member
Thread Starter
 
hman0217's Avatar
 
Join Date: Jul 2016
Location: Brooklyn, NY
Posts: 29

Bikes: Surly LHT, Lynskey Cooper cx, Specialized Stumpjumper 26er, Jamis Dragonslayer

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 17 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
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
hman0217 is offline  
Old 05-13-19, 08:09 AM
  #7  
fietsbob 
coprolite
 
fietsbob's Avatar
 
Join Date: Jun 2010
Location: NW,Oregon Coast
Posts: 41,481

Bikes: 8

Mentioned: 183 Post(s)
Tagged: 0 Thread(s)
Quoted: 6724 Post(s)
Likes: 0
Liked 141 Times in 119 Posts
I used a plastic pen body to push the pad pistons back , (after removing the pads).. on TRP Hy Rd.
fietsbob is offline  
Old 05-14-19, 11:08 AM
  #8  
wgscott
Occam's Rotor
 
wgscott's Avatar
 
Join Date: Jul 2013
Location: The Timbers of Fennario (CL77)
Posts: 4,787

Bikes: Steel

Mentioned: 61 Post(s)
Tagged: 0 Thread(s)
Quoted: 2366 Post(s)
Liked 152 Times in 90 Posts
Originally Posted by hman0217 View Post
it seemed to open on one side and not the other.
One side moves more than the other by design, but both pistons should be flat against the caliper when fully pushed in.
wgscott is offline  
Old 05-14-19, 11:56 AM
  #9  
fietsbob 
coprolite
 
fietsbob's Avatar
 
Join Date: Jun 2010
Location: NW,Oregon Coast
Posts: 41,481

Bikes: 8

Mentioned: 183 Post(s)
Tagged: 0 Thread(s)
Quoted: 6724 Post(s)
Likes: 0
Liked 141 Times in 119 Posts
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..



...
fietsbob is offline  

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

Copyright 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.