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

Shimano Hydraulic Disc Brake issue

Notices
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.

Shimano Hydraulic Disc Brake issue

Old 06-26-22, 01:10 PM
  #1  
rbrides
Curmudgeon
Thread Starter
 
rbrides's Avatar
 
Join Date: Nov 2018
Location: Triangle NC
Posts: 248

Bikes: Specialized Diverge Comp

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 105 Post(s)
Liked 18 Times in 15 Posts
Shimano Hydraulic Disc Brake issue

Simply, one of the pistons does not return after releasing the front brakes on my road bikeís Shimano Ultegra hydraulic disc brakes and causes the dreaded brake squeal. Usually the squeal goes away when I lightly pump the brake 3-4. Sometimes it it needs 8-10 pumps. No squeal while applying the brakes, only after releasing them.

Iíve follow all the procedures I know to clean pistons and calipers, including Park Toolsí and other reliable sources. Changing pads and spring clips has not resolved the issue. Iíve tried to determine if the piston is mis-aligned and thus not moving in/out properly but it does not appear to be so.

any practical advice from others who have experienced and resolved this issue?
rbrides is offline  
Old 06-26-22, 08:50 PM
  #2  
cxwrench
Senior Member
 
cxwrench's Avatar
 
Join Date: Jul 2013
Location: Nor-Cal
Posts: 3,317

Bikes: lots

Mentioned: 6 Post(s)
Tagged: 0 Thread(s)
Quoted: 1657 Post(s)
Liked 2,449 Times in 1,267 Posts
Either you're not actually cleaning/lubing them or it's some other mystery. A piston that's mostly in the bore can't be 'mis-aligned'. If it's mostly out of the bore that's another story.
cxwrench is offline  
Likes For cxwrench:
Old 06-27-22, 06:25 AM
  #3  
andrewclaus
Senior Member
 
Join Date: Feb 2012
Location: Golden, CO and Tucson, AZ
Posts: 2,505

Bikes: 2016 Fuji Tread, 1983 Trek 520

Mentioned: 13 Post(s)
Tagged: 0 Thread(s)
Quoted: 570 Post(s)
Liked 411 Times in 281 Posts
Have you exercised each piston independently to assure the seals are clean and functioning? If so, it may be time to replace seals and pistons.
andrewclaus is offline  
Likes For andrewclaus:
Old 06-27-22, 09:57 AM
  #4  
rbrides
Curmudgeon
Thread Starter
 
rbrides's Avatar
 
Join Date: Nov 2018
Location: Triangle NC
Posts: 248

Bikes: Specialized Diverge Comp

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 105 Post(s)
Liked 18 Times in 15 Posts
Originally Posted by cxwrench View Post
Either you're not actually cleaning/lubing them or it's some other mystery. A piston that's mostly in the bore can't be 'mis-aligned'. If it's mostly out of the bore that's another story.
I am able to push them fully back in. I clean them with Isopropyl alcohol. What is your method for lubing them?
rbrides is offline  
Old 06-27-22, 10:02 AM
  #5  
rbrides
Curmudgeon
Thread Starter
 
rbrides's Avatar
 
Join Date: Nov 2018
Location: Triangle NC
Posts: 248

Bikes: Specialized Diverge Comp

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 105 Post(s)
Liked 18 Times in 15 Posts
Originally Posted by andrewclaus View Post
Have you exercised each piston independently to assure the seals are clean and functioning? If so, it may be time to replace seals and pistons.
"independently", maybe not. I remove the pads and pump them to expose the pistons for cleaning and press them back in, work them in/out a few times pumping the brake lever and push in again. What do you do? Hold one in and work the other "independently"?
rbrides is offline  
Old 06-27-22, 11:05 AM
  #6  
andrewclaus
Senior Member
 
Join Date: Feb 2012
Location: Golden, CO and Tucson, AZ
Posts: 2,505

Bikes: 2016 Fuji Tread, 1983 Trek 520

Mentioned: 13 Post(s)
Tagged: 0 Thread(s)
Quoted: 570 Post(s)
Liked 411 Times in 281 Posts
Originally Posted by rbrides View Post
"independently", maybe not. I remove the pads and pump them to expose the pistons for cleaning and press them back in, work them in/out a few times pumping the brake lever and push in again. What do you do? Hold one in and work the other "independently"?
Yep. Get an assistant to work the lever slowly, push piston back in if needed, get each piston to react identically. I saw that in one of the Park Tools videos. Maybe you missed that one--there are a few of them. Careful cleaning first is key.
andrewclaus is offline  
Likes For andrewclaus:
Old 06-27-22, 11:20 AM
  #7  
Polaris OBark
Dirt Roadie
 
Polaris OBark's Avatar
 
Join Date: Jan 2022
Posts: 1,235
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 645 Post(s)
Liked 822 Times in 498 Posts
Probably the safest thing to lubricate (if absolutely necessary) is Shimano mineral oil. Use about 1/10th what you think you need, and then spend the rest of the day wiping it off. Any extra will be a dust magnet and make the problem 10 times worse than it is now.
Polaris OBark is offline  
Likes For Polaris OBark:
Old 06-27-22, 12:53 PM
  #8  
vespasianus
Senior Member
 
Join Date: Jul 2019
Location: In the south but from North
Posts: 521

Bikes: Turner 5-Spot Burner converted; IBIS Ripley, Specialized Crave, Tommasini Sintesi, Cinelli Superstar, Tommasini X-Fire Gravel

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 285 Post(s)
Liked 268 Times in 147 Posts
Originally Posted by rbrides View Post
I am able to push them fully back in. I clean them with Isopropyl alcohol. What is your method for lubing them?
First, when the pads are out, clean with alcohol. Let it dry and gently, and I mean gently, pump the brake lever once and see the piston extend out a bit. Pump the lever one or two more times gently to have the pistons extend out.

Now, get a Q-tip and a little bit of mineral oil (if that is what your brake uses). Dip the Q-tip head into the oil and use it to moisten all around the exposed piston. Get the piston nice and moist with the mineral oil.

After you have coated the pistons well (and really focusing on the part right where the seals are) push the pistons back into the caliper using a plastic tire lever.

Repeat the process (but skip the alcohol wipe) maybe 2-5 times. After the last "push back" of the pistons, clean with alcohol and put back your pads.
vespasianus is offline  
Likes For vespasianus:
Old 06-27-22, 01:38 PM
  #9  
rbrides
Curmudgeon
Thread Starter
 
rbrides's Avatar
 
Join Date: Nov 2018
Location: Triangle NC
Posts: 248

Bikes: Specialized Diverge Comp

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 105 Post(s)
Liked 18 Times in 15 Posts
Originally Posted by vespasianus View Post
First, when the pads are out, clean with alcohol. Let it dry and gently, and I mean gently, pump the brake lever once and see the piston extend out a bit. Pump the lever one or two more times gently to have the pistons extend out.

Now, get a Q-tip and a little bit of mineral oil (if that is what your brake uses). Dip the Q-tip head into the oil and use it to moisten all around the exposed piston. Get the piston nice and moist with the mineral oil.

After you have coated the pistons well (and really focusing on the part right where the seals are) push the pistons back into the caliper using a plastic tire lever.

Repeat the process (but skip the alcohol wipe) maybe 2-5 times. After the last "push back" of the pistons, clean with alcohol and put back your pads.
Thanks.
rbrides is offline  
Old 06-27-22, 01:39 PM
  #10  
rbrides
Curmudgeon
Thread Starter
 
rbrides's Avatar
 
Join Date: Nov 2018
Location: Triangle NC
Posts: 248

Bikes: Specialized Diverge Comp

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 105 Post(s)
Liked 18 Times in 15 Posts
Originally Posted by Polaris OBark View Post
Probably the safest thing to lubricate (if absolutely necessary) is Shimano mineral oil. Use about 1/10th what you think you need, and then spend the rest of the day wiping it off. Any extra will be a dust magnet and make the problem 10 times worse than it is now.
Thanks
rbrides is offline  
Old 06-27-22, 01:40 PM
  #11  
Polaris OBark
Dirt Roadie
 
Polaris OBark's Avatar
 
Join Date: Jan 2022
Posts: 1,235
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 645 Post(s)
Liked 822 Times in 498 Posts
Originally Posted by rbrides View Post
Thanks
@vespasianus for the win (detail)
Polaris OBark is offline  
Likes For Polaris OBark:
Old 06-27-22, 02:14 PM
  #12  
cxwrench
Senior Member
 
cxwrench's Avatar
 
Join Date: Jul 2013
Location: Nor-Cal
Posts: 3,317

Bikes: lots

Mentioned: 6 Post(s)
Tagged: 0 Thread(s)
Quoted: 1657 Post(s)
Liked 2,449 Times in 1,267 Posts
Originally Posted by rbrides View Post
I am able to push them fully back in. I clean them with Isopropyl alcohol. What is your method for lubing them?
Q-tip and Shimano mineral oil.
cxwrench is offline  
Likes For cxwrench:
Old 06-27-22, 04:19 PM
  #13  
greysquirrel
Newbie
 
Join Date: Apr 2010
Posts: 57
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 17 Post(s)
Likes: 0
Liked 5 Times in 5 Posts
I had a GRX disc brake that did the same thing. Tried cleaning but didn't work. 1 pad was always farther out then the other. I just repositioned the caliper to center the rotor. Solved the problem.

Originally Posted by rbrides View Post
Simply, one of the pistons does not return after releasing the front brakes on my road bikeís Shimano Ultegra hydraulic disc brakes and causes the dreaded brake squeal. Usually the squeal goes away when I lightly pump the brake 3-4. Sometimes it it needs 8-10 pumps. No squeal while applying the brakes, only after releasing them.

Iíve follow all the procedures I know to clean pistons and calipers, including Park Toolsí and other reliable sources. Changing pads and spring clips has not resolved the issue. Iíve tried to determine if the piston is mis-aligned and thus not moving in/out properly but it does not appear to be so.

any practical advice from others who have experienced and resolved this issue?
greysquirrel is offline  
Likes For greysquirrel:

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 - Do Not Sell My Personal Information -

Copyright © 2021 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.