SRAM Guide RS Brakes - Lever slow to return

[jarrod839]

Have the ultimate's fixed this problem or as level internals are the same it'll just happen to them too?
Big outlay for the E4's, but Merlin have them for $360 at the moment.. Otherwise keep warranting the guides I guess. Seems no permanent fix though is there? - going to keep screwing up?

the ultimates have solved this issue as they have upgraded internals and a aluminum piston instead of plastic. Most people if out of warranty are upgrading to ultimate levers as there is only some success rate replacing the internals.

My left hand RSC has shat itself but will most likely just upgrade to ultimates.

 

[JTmofo]

Yeah true, the E4's actually pretty good priced.. Some say lacking power compared to the others?

That's a strong negative. My experience with Hope brakes (been running E4's on a 160mm Enduro bike for 3 years) is that they have more power than anything else I've used, along with feel/feedback/modulation you cannot get with any other brand/model.

Best bang for your $$$ of any brakes on the market. Couple that with easy home servicing (albeit I have only bled mine once as I felt sorry for neglecting them), ease of getting spares on the web and robustness.... I wouldnt buy anything else (unless i didnt have the coin for them)

I recently built a new build, ran out of cash and bought XT M8000...... What a disappointment! :noidea:

 

[JoelFitz]

Can you run them with shimano/sram rotors to start with? Also I suppose they need adapters for the fork/frame? Currently have pikes with 180mm on the front and 160mm rear.

That's a strong negative. My experience with Hope brakes (been running E4's on a 160mm Enduro bike for 3 years) is that they have more power than anything else I've used, along with feel/feedback/modulation you cannot get with any other brand/model.

Best bang for your $$$ of any brakes on the market. Couple that with easy home servicing (albeit I have only bled mine once as I felt sorry for neglecting them), ease of getting spares on the web and robustness.... I wouldnt buy anything else (unless i didnt have the coin for them)

I recently built a new build, ran out of cash and bought XT M8000...... What a disappointment! :noidea:

 

[TheAzza]

That's a strong negative. My experience with Hope brakes (been running E4's on a 160mm Enduro bike for 3 years) is that they have more power than anything else I've used, along with feel/feedback/modulation you cannot get with any other brand/model.

Best bang for your $$$ of any brakes on the market. Couple that with easy home servicing (albeit I have only bled mine once as I felt sorry for neglecting them), ease of getting spares on the web and robustness.... I wouldnt buy anything else (unless i didnt have the coin for them)

I recently built a new build, ran out of cash and bought XT M8000...... What a disappointment! :noidea:

I second this. I just replaced a set of Zees with E4's and they are brutally powerful and easily modulated. I am not exactly a lightweight either, not huge, but not hugely light.

 

[Boom King]

Can you run them with shimano/sram rotors to start with? Also I suppose they need adapters for the fork/frame? Currently have pikes with 180mm on the front and 160mm rear.

Your current rotors and adapters will be fine.

 

[TheAzza]

Can you run them with shimano/sram rotors to start with? Also I suppose they need adapters for the fork/frame? Currently have pikes with 180mm on the front and 160mm rear.

I ran them with Ice Techs for a very very short while and did notice the difference when I went to the Hopes.
Pushys have decent prices on Hope rotors.

 

[JTmofo]

Can you run them with shimano/sram rotors to start with? Also I suppose they need adapters for the fork/frame? Currently have pikes with 180mm on the front and 160mm rear.

I ran into problems with adapters for E4's due to the 4 piston arrangement. I was run a 203mm rotor so needed a Post mount 160mm to 203mm (Hope Mount C). It has a pretty big bow in the adapter to accommodate the 4 piston caliper. Doesn't look like that will be an issue running a 180mm on a 160mm post mount (Hope Mount L)
I always buy Hope adaptors now regardless.

Doesnt look like this will be an issue running 180mm rotors...adapters looks very similar to Shimano.

http://www.hopetech.com/wp-content/uploads/2015/10/Hope-Brake-mounts-2016-page1-ok.pdf

 

[hifiandmtb]

Hey Link - are these the Guides I sold you?

 

[link1896]

Hey Link - are these the Guides I sold you?

Ones I bought from you are still on the XC bike, the rear lever has become sticky, will mod/rebuild my second set and swap them in. Photo of the version 1 piston that was stuck really badly are from my second set, but I'm expecting the same on your old set.

 

[Jesterarts]

Quick disassembly this morning.

I have v1, very stuck pistons. Took a lot of force with a small Allen key to move the piston out of the lever.

I can see how to vacuum bleed

View attachment 332292

Thanks for sharing the picture. I want to take mine apart now just to be involved...

Well, my new internals, my bleed kit, dot fluid and avid dot grease should all arrive end of next week. So I'll tear mine apart, see what I find and share.

I'm hoping the new piston design will solve the issue. Though if not, I can always sand down the current pistons in 12 months and pop them back in.

My father in law also has a metal lathe... so depending how crazy I want to go, I might mill some aluminium pistons...

 

[Boom King]

What is actually causing them to stick after a period of time?

 

[Jesterarts]

What is actually causing them to stick after a period of time?

I don't think anyone has definitively confirmed it. But based on what I have been reading it's the expansion of the piston plastic as it absorbs either the brake fluid or moisture.

That's why just taking it apart and giving it a clean doesn't work, since the piston is actually a bit bigger.

Some further reading about plastics lead me to discover that different plastics have different water absorption ratios. I suspect, that the plastic used in the Guide pistons is cheaper than other plastics with a lower water absorption ratio.

Some people have suggested the o-rings play a part too, but people are getting results by removing and sanding the original piston so I would think if they do contribute to the issue, it's only in a minimal way.

Given the redesign of the RS piston from the one that is Link shared to the new one, where the whole chunky bit is gone, that would suggest is the key problem area.

I imagine the two narrow contact points also expand and drag, but they that must not be sufficient enough to cause the rather terminal issue's the original pistons are experiencing.

 

[link1896]

I don't think anyone has definitively confirmed it. But based on what I have been reading it's the expansion of the piston plastic as it absorbs either the brake fluid or moisture.

That's why just taking it apart and giving it a clean doesn't work, since the piston is actually a bit bigger.

Some further reading about plastics lead me to discover that different plastics have different water absorption ratios. I suspect, that the plastic used in the Guide pistons is cheaper than other plastics with a lower water absorption ratio.

Some people have suggested the o-rings play a part too, but people are getting results by removing and sanding the original piston so I would think if they do contribute to the issue, it's only in a minimal way.

Given the redesign of the RS piston from the one that is Link shared to the new one, where the whole chunky bit is gone, that would suggest is the key problem area.

I imagine the two narrow contact points also expand and drag, but they that must not be sufficient enough to cause the rather terminal issue's the original pistons are experiencing.

I'll take a closer look tonight, but I think the piston might be bent, rub marks are only on one side of the chunky bit

 

[JoelFitz]

I thought all RSC had the revised piston design and r/rs was the one with the larger plastic section in the piston?

Sent from my XT1092 using Tapatalk

 

[link1896]

I'll take a closer look tonight, but I think the piston might be bent, rub marks are only on one side of the chunky bit

Piston rolls straight on a mirror, not bent.

Purely speculation still as I've only had a rushed look, looks like it might be a combination of the plastic is not dot fluid compatible as suggested and the lever does not load the piston in a fashion that's totally parallel to its direction of travel.

Epic fails yet again if this is the case

Will be measuring the pistons and drawing up an aluminium piston design. I've seen a mixture of O-Rings, quad rings and these funky seals on automotive master pistons. I'm tempted to use quad rings if they don't mess with the ports to the reservoir.

Should I have to fix this shit? NO. Will I? Yes, I like Guides modulation and the whole matchmaker system. But fuck it makes me angry.

 

[waldog]

Possibly completely unrelated to anything here, but I just blew up a two week old guide caliper. Assuming one of the many seals failed, spooged fluid everywhere and left me with no brake lever at all.

Happened while on holiday, now don't have bike as I'm still on holiday, but will be checking it out properly in the next week or so.

 

[link1896]

Possibly completely unrelated to anything here, but I just blew up a two week old guide caliper. Assuming one of the many seals failed, spooged fluid everywhere and left me with no brake lever at all.

Happened while on holiday, now don't have bike as I'm still on holiday, but will be checking it out properly in the next week or so.

Fairly unusual for a caliper seal to let go, but it is sram after all. Bet it was pinched when the 8 year old assembled it.

 

[JoelFitz]

So I tried removing the piston from the sticky lever, cleaned it up, bit of dot/rubber safe grease on the seals and reassembled. Felt find for a bit, then left bike in sun for 30mins. Lever would not return at all after that.
So pulled apart again, this time with some verniers I measured each of the raised sections along the piston, 2x of them with a bit larger than the 3rd. So I sanded those down with some real fine wet n dry paper. Got them all the same size. Reassembled, left bike in sun. So far so good!

 

[jarrod839]

Keep us posted on how the Re-builds hold up as interesting to see how long they last.

 

[JoelFitz]

Just for the record, the pistons in mine are like the image below.. I think some people are commenting that this design doesn't suffer the same issue, but it does..