Notices
Cyclocross and Gravelbiking (Recreational) This has to be the most physically intense sport ever invented. It's high speed bicycle racing on a short off road course or riding the off pavement rides on gravel like : "Unbound Gravel". We also have a dedicated Racing forum for the Cyclocross Hard Core Racers.

SRam Hydro brakes…

Old 05-14-22, 11:41 AM
  #1  
Fentuz
Senior Member
Thread Starter
 
Join Date: Aug 2014
Location: UK
Posts: 714

Bikes: Dahon Jetstream p8 (sold), customized Dahon Helios x10, customzed Dahon Smooth Hound x9,customized Dahon Hammerhead 8.0 d7, Planet X Free Ranger (mullet setup 1x11), Planet X Giovanissimi 20 (1x9), Frog 52 (1x9) and Frog 48 1s

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 249 Post(s)
Liked 221 Times in 162 Posts
SRam Hydro brakes…

After a winter of mud, i noticed that the rival brake lever were getting closer to the handle bar. The squeeze increased as the pads wore out.
I aware that the reach is adjustable but the issue more the added degree of rotation.

Although I do most servicing/repair/upgrade myself, i took the bike to a pro shop for the yearly inspections (bb swap, wheel check, fluid bleed). The bike shop said the brakes were fine and it is just a result of the wear and tear.

so to get the brake feel back as I like it, new pads seemed to be the answer but was it?
the pads lost 0.15mm per side (2.05mm material left), discs are 0.05mm worn (0.2mm above minimal thickness).

So I took my filler blade and found there was just above 0.13mm clearance between pads and disc on either side.
pick up a can of coke (best and cheapest 0.1mm shim material) and cut some pads back shims (pad backing plate contour) as fitted a shim on either side.
results is good; brake feel is back to how I like it…
cost: not much
Fentuz is offline  
Old 05-15-22, 09:59 PM
  #2  
Chilepines
Junior Member
 
Join Date: Jul 2020
Location: New Hampshire
Posts: 194

Bikes: 1984 homemade 531SL road bike; 1988 Ritchey TimberComp; 1997 Nashbar tandem; 1998 Kona Explosif; Specialized Epic, Scott CR1 Pro; Salsa Beargrease; Curtlo custom Tandem, Curtlo custom S3 steel gravel bike.

Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 67 Post(s)
Liked 49 Times in 37 Posts
Hydraulic brakes are self-adjusting (or should be) so if the pads are not as close to the rotor and the lever feels soft, you probably need to bleed the brakes. You could also have a warped rotor causing what you are describing.
Chilepines is offline  
Old 05-16-22, 02:25 AM
  #3  
Fentuz
Senior Member
Thread Starter
 
Join Date: Aug 2014
Location: UK
Posts: 714

Bikes: Dahon Jetstream p8 (sold), customized Dahon Helios x10, customzed Dahon Smooth Hound x9,customized Dahon Hammerhead 8.0 d7, Planet X Free Ranger (mullet setup 1x11), Planet X Giovanissimi 20 (1x9), Frog 52 (1x9) and Frog 48 1s

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 249 Post(s)
Liked 221 Times in 162 Posts
Originally Posted by Chilepines
Hydraulic brakes are self-adjusting (or should be) so if the pads are not as close to the rotor and the lever feels soft, you probably need to bleed the brakes. You could also have a warped rotor causing what you are describing.
Discs are fine (dti clocked when the wheel were checked) , fluid was bled by a pro, yes twin pot calipers self adjust but I found that you can feel a difference when the pads start to wear. I used to feel the same on my race car with twin pots and no servo despite bleeding and reverse bleeding. When I fitted brand new pagid rs14, it was rock solid with very little pedal travel and after a couple of races, the travel was longer despite bleeding and use or 660 racing fluid.

Note that on the bike, the feel is not spongy, the braking power is still there and does not fade, the lever just travels more possibly because the pots retract back to much in the caliper housing. May be, when there is not pressure, the retracting springs are too strong causing the pads to retract back more than they really need. I have always wondered why Bike hydro calipers required those pad springs, cars don't need it and I don't believe motorbike have them either. Are these springs artefact of the mechanical disc system (like on some car hand brake/ebrake/parking brake)?

I also noticed that on the gorilla pads I currently use, the pots created an indent in the coating of the back plate (didn't get that on galfer or sram pads). I'm not to concern about that as it can help locating the pad on the piston/pot reducing potential movement /rattling when pressure is not applied. (known issue with AP twin pot calipers and the good old girling).

Last edited by Fentuz; 05-16-22 at 02:31 AM.
Fentuz is offline  
Old 05-16-22, 04:28 AM
  #4  
dsaul
Senior Member
 
Join Date: Jan 2013
Location: South Jersey
Posts: 2,258
Mentioned: 18 Post(s)
Tagged: 0 Thread(s)
Quoted: 712 Post(s)
Liked 793 Times in 471 Posts
Originally Posted by Chilepines
Hydraulic brakes are self-adjusting (or should be) so if the pads are not as close to the rotor and the lever feels soft, you probably need to bleed the brakes. You could also have a warped rotor causing what you are describing.
I can tell you from experience that SRAM road hydro levers are not self adjusting. The lever throw gets longer as the pads wear, until you have to replace the pads because the levers are hitting the bars.
dsaul is offline  
Old 05-17-22, 02:41 PM
  #5  
msu2001la
Senior Member
 
msu2001la's Avatar
 
Join Date: Mar 2006
Location: Chicago, IL, USA
Posts: 2,870
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 1455 Post(s)
Liked 1,477 Times in 867 Posts
Originally Posted by dsaul
I can tell you from experience that SRAM road hydro levers are not self adjusting. The lever throw gets longer as the pads wear, until you have to replace the pads because the levers are hitting the bars.
SRAM disagrees with this statement.
https://www.sram.com/en/service/arti...e%20pad%20wear.
msu2001la is offline  
Old 05-17-22, 03:29 PM
  #6  
msu2001la
Senior Member
 
msu2001la's Avatar
 
Join Date: Mar 2006
Location: Chicago, IL, USA
Posts: 2,870
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 1455 Post(s)
Liked 1,477 Times in 867 Posts
Originally Posted by Fentuz
After a winter of mud, i noticed that the rival brake lever were getting closer to the handle bar. The squeeze increased as the pads wore out.
I aware that the reach is adjustable but the issue more the added degree of rotation.

Although I do most servicing/repair/upgrade myself, i took the bike to a pro shop for the yearly inspections (bb swap, wheel check, fluid bleed). The bike shop said the brakes were fine and it is just a result of the wear and tear.

so to get the brake feel back as I like it, new pads seemed to be the answer but was it?
the pads lost 0.15mm per side (2.05mm material left), discs are 0.05mm worn (0.2mm above minimal thickness).

So I took my filler blade and found there was just above 0.13mm clearance between pads and disc on either side.
pick up a can of coke (best and cheapest 0.1mm shim material) and cut some pads back shims (pad backing plate contour) as fitted a shim on either side.
results is good; brake feel is back to how I like it…
cost: not much
I can't believe I'm typing this, but I would definitely recommend you remove the DIY Coke can shims you installed, and figure out what is causing the problem and fix it. SRAM brake systems are poorly designed and notoriously difficult for inexperienced shops to troubleshoot. If your shop is sending you home with malfunctioning brakes and just telling you it's normal, you need to find a new shop that has experience working on SRAM hydro brakes. The lever bottoming out is not normal, nor is it caused by worn pads. SRAM brakes (like nearly every hydro brake system out there) are supposed to self adjust to compensate for pad wear. If your system isn't self-adjusting, something is probably stuck/broken or the contact point/reach adjustement has been changed, etc.. My guess is you've got a stuck piston(s).
msu2001la is offline  
Old 05-17-22, 07:31 PM
  #7  
dwmckee
Senior Member
 
dwmckee's Avatar
 
Join Date: Jun 2008
Location: Pittsburgh, PA
Posts: 2,468

Bikes: Co-Motion Cappuccino Tandem,'88 Bob Jackson Touring, Co-Motion Cascadia Touring, Open U.P., Ritchie Titanium Breakaway, Frances Cycles SmallHaul cargo bike. Those are the permanent ones; others wander in and out of the stable occasionally as well.

Mentioned: 7 Post(s)
Tagged: 0 Thread(s)
Quoted: 427 Post(s)
Likes: 0
Liked 339 Times in 229 Posts
Originally Posted by msu2001la
I can't believe I'm typing this, but I would definitely recommend you remove the DIY Coke can shims you installed, and figure out what is causing the problem and fix it. SRAM brake systems are poorly designed and notoriously difficult for inexperienced shops to troubleshoot. If your shop is sending you home with malfunctioning brakes and just telling you it's normal, you need to find a new shop that has experience working on SRAM hydro brakes. The lever bottoming out is not normal, nor is it caused by worn pads. SRAM brakes (like nearly every hydro brake system out there) are supposed to self adjust to compensate for pad wear. If your system isn't self-adjusting, something is probably stuck/broken or the contact point/reach adjustement has been changed, etc.. My guess is you've got a stuck piston(s).
Yup! Or contaminated pads and/or rotors also.
dwmckee is offline  
Old 05-17-22, 10:47 PM
  #8  
Fentuz
Senior Member
Thread Starter
 
Join Date: Aug 2014
Location: UK
Posts: 714

Bikes: Dahon Jetstream p8 (sold), customized Dahon Helios x10, customzed Dahon Smooth Hound x9,customized Dahon Hammerhead 8.0 d7, Planet X Free Ranger (mullet setup 1x11), Planet X Giovanissimi 20 (1x9), Frog 52 (1x9) and Frog 48 1s

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 249 Post(s)
Liked 221 Times in 162 Posts
Like I said, there is no brake fade, just longer travel.
i looked at the pistons and they move freely, they are clean. I cannot see and issue with the system, it works similarly to a AP or Brembo or Girling setup from a caliper system point of view.
the only thing different is the pads back spring.

Why did sram put that there? The spring keep pushing back the pad backing plate again the caliper housing. Basically, for those you have replace pads on cars, the spring is doing what you would do to push back the piston is the housing before fitting new pads.

self adjusting should/would work if there was nothing constantly backing the pads back
Fentuz is offline  
Old 05-18-22, 03:11 PM
  #9  
chaadster
Thread Killer
 
Join Date: Aug 2008
Location: Ann Arbor, MI
Posts: 12,373

Bikes: 15 Kinesis Racelight 4S, 76 Motebecane Gran Jubilée, 17 Dedacciai Gladiatore2, 12 Breezer Venturi, 09 Dahon Mariner, 12 Mercier Nano, 95 DeKerf Team SL, 19 Tern Rally, 21 Breezer Doppler Cafe+, 19 T-Lab X3, 91 Serotta CII

Mentioned: 30 Post(s)
Tagged: 0 Thread(s)
Quoted: 3078 Post(s)
Liked 1,631 Times in 1,005 Posts
Originally Posted by Fentuz
Like I said, there is no brake fade, just longer travel.
i looked at the pistons and they move freely, they are clean. I cannot see and issue with the system, it works similarly to a AP or Brembo or Girling setup from a caliper system point of view.
the only thing different is the pads back spring.

Why did sram put that there? The spring keep pushing back the pad backing plate again the caliper housing. Basically, for those you have replace pads on cars, the spring is doing what you would do to push back the piston is the housing before fitting new pads.

self adjusting should/would work if there was nothing constantly backing the pads back
That spring is definitely not exerting enough force to displace the pistons, so I think you’re creating your own boogieman here…
chaadster is offline  
Likes For chaadster:
Old 06-01-22, 02:12 PM
  #10  
Phatman
Senior Member
 
Join Date: Sep 2002
Location: NC
Posts: 3,594
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 120 Post(s)
Liked 96 Times in 50 Posts
The spring is just there to prevent the pads from rattling in the caliper. If they were allowed to move freely on the retainer pin, they'd buzz the rotor every time you moved the bike side to side and you'd slowly lose your mind. BTW, cars do use anti-rattle springs, here's one on a typical BMW brake:



It's the skinny metal part clipped onto the two vertically oriented metal holes. I've left one off by accident, believe me, you know it.
Phatman 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 © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.