Sram guide ultimate rear brake spongy

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Sram guide ultimate rear brake spongy
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Posted: Jan 23, 2020 at 14:37 Quote
i had a sram guide RS. brand new. exactly the same issue. shop said nothing wrong. immediately paid 100 bucks and went back to shimano m6000 and problem solved, bike stops again, arms no longer sore.

PS having said that, i still have them RS, and want to mount to a project bike, going to the shop to pick up some dot 5.1 to bleed and i'll report back if it fixes it.

Posted: Jan 24, 2020 at 8:32 Quote
From reading other posts on this, on different forums - for new brakes it is highly suggested to go through the bed in procedure. I know that really helped on my wife's bike with hydraulic brakes (I forget the brand though)

Posted: Jan 25, 2020 at 12:13 Quote
UTMTB77 wrote:
No matter what I do I seem to get a spongy rear brake with my sram guide ultimates rear brake, its not horrible it just never feels as solid as my front feels. I have tried all the steps and different bleed techniques I can find online, does anybody have any of the same issues? maybe this is normal maybe I am missing something? Anybody have any tricks to getting them consistent and solid? I know its possible because I love the way my front feels.

Any help would be great!

I had the same issue. sram guide RS, rear more spongy than front. i think it's just the hose length. when i squeeze the lever the hose visibly moves - a lot.

i have just bled my brakes thoroughly. and the front is every so slightly less spongy than the rear. when compared to my shimano, the shimano when it engages the lever hits a brick wall. the sram the lever requires more effort to pull and when it engages it doesn't hit a brick wall but more like a rubber wall.

to get to nearly as solid as the front, i took off the brakes from the bike and i gave the caliper and lever a hard shake before and during bleed. that way i could get more air out. apparently the sram has 2 circuits vs shimano's single circuit. also watch this video, from exactly 10:48. note I didn't do this step as i spent a whole day yesterday bleeding the darn brakes as it's quite more involved than the shimanos and I was missing one crucial tool, the clip and turn lock in bit.

https://youtu.be/ys9bUOJ0qg0?t=647

Posted: Jan 27, 2020 at 7:11 Quote
Any chance you could make a YouTube video to show these mods??

slabshaft wrote:
Problem: My Guide R brakes were always mushy and I could easily pull them to the handlebar. The bike still stopped, but it’s very awkward and just plain stupid that I have to pull the grips all the way to the bar. This mushy feeling was due to air in the system, not enough fluid in the system, or ‘not being pressurize’ (which will make sense if you watch this video). They’ve been like this since the brakes/bike were brand new.
Bleeding them to either this video below, or the official SRAM bleed procedure video did literally nothing at all to improve this mushy feel.

But…I think I cracked the code on how to fix this, at least for my opinion of what the brakes should feel like…and these Guide R brakes should feel as good as XT brakes!
Watch this entire video first from GMBN Tech:
https://www.youtube.com/watch?v=Xp_s-CK9CwA

This video is very detailed, does a great job of explaining all the tools/steps and it seems to match the official SRAM bleed process.
I’m referencing this video because it feels more thought out/slower paced compared to the official SRAM video. My mods apply to this or SRAM’s video, but these time stamps below reference the GMBN Tech video, not the SRAM video.

My mods apply to just BEFORE removal of the fitting from the brake lever at around the 11:42 mark.

Some notes from this video:
11:32, he closes the Bleeding Edge fitting…this is correct, you have to do this to pull air out of the lever!

11:42, he mentions “pressurize the system”, this is the catch…he’s right, the system DOES need to be pressurized...keep reading.

11:52, he mentions “pull the lever in and release”.

12:01, he mentions “pulling up on the syringe” (to pull out air bubbles), then he pushes down on the syringe to pressurize the lever again, but I do this step differently.

12:11, he mentions “push back in one time hard to pressurize the system”…but, the step below ruins this!

12:34, he has the syringe clamp closed and unscrews the fitting from the lever. THIS STEP IS THE PROBLEM!!
If the “system has to be pressurized”, removing the lever syringe fitting exposes the fluid to the atmosphere, instantly losing ALL pressure in the system!! For me, this resulted in a brake that was literally just as mushy after bleeding as before I started…what was the purpose of even bleeding them if it makes zero difference?

Here are the process mods below I made that resulted in a firm lever feel, which I could no longer pull to the handlebar, which was every bit as good as the XT brakes on my other bike.
One disclaimer first: As I have repeated these mods a few times, there is a risk: There could be TOO MUCH pressure in the system, resulting in pads that always rub on the disc because the pistons cannot retract into their bores. I mention how to fix this later…
1. For pulling air out of the lever:
a. At the 11:52 and 12:01 steps:
b. Here is my mod:
i. Make sure to pull as much vacuum as you can on the syringe AS YOU PULL THE LEVER IN AND RELEASE!
ii. Pull vacuum and hold it for several seconds…pull lever in…release lever…repeat. Do this at least 5-6 times.
c. Then push the syringe in one final time. Even though you will lose this pressure when you remove the fitting from the lever, it’s required to ensure the reservoir in the lever is full.
i. While pushing down on syringe, pull the lever in. It probably feels like you want it to, right!?
d. Remove the fitting from the lever and you’ll notice it instantly releases any pressurization you achieved, along with a fair amount of fluid getting pushed out…resulting in zero internal system pressure.
i. You probably now have a lever that is just as mushy as when you started, at least I did, not matter how well I performed the process. Keep reading.
e. Reinstall the lever plug, clean everything up.

2. Here is the mod that made ALL the difference for me:
a. Go back to the Bleeding Edge fitting at the caliper.
b. OPEN it back up, then WHILE PUSHING IN ON THE SYRINGE pretty hard, CLOSE the Bleeding Edge fitting:
i. If you imagine pressing on the syringe on a scale from 0 (not pushing) to 10 (pushing as hard as you can), push at about a 6-7.
c. This is the ONLY way you will achieve internal pressure in the system above atmospheric pressure, which is to pressurize while closing the system!

3. Put everything back to normal, install all the pads, clips, wheels, etc.

4. Remember the disclaimer above?
a. If you spin the wheel, are the pads obviously rubbing a lot?
i. Meaning the wheel spins less than 2-3 revolutions.
ii. If this is true, you have to release some pressure/fluid from the system.
b. Go back to the lever plug, curl some paper towels around the plug, but ensure you can still see the plug, and see if/when fluid comes out.
c. You need to ‘burp’ the plug…open it gradually until some fluid pushes out, it may push out quickly, so be ready!
d. Once you see several drops worth of fluid come out, quickly re-tighten the lever plug.
e. Do the pad rubbing/wheel spin test again.
f. Repeat this burping process a few more times as required.

5. For me, this process resulted in a ‘better than new’ feeling in both levers, just as good as my XT brakes.

6. There was some residual brake pad rubbing, like I had just put in new pads. This will go away after a few rides, just like it does with new pads. As the pads wear slightly, they create a clearance gap, resulting in zero rubbing.
a. When you eventually have to replace pads, I imagine you’ll have to ‘burp’ the system again so the pistons retract in their bores sufficient to install the new thicker pads.

I know that was a lot of words to describe two relatively simple mods, but I wanted to be as detailed as I could, because bleeding the Guide R brakes is a huge butt-pain relative to XT brakes, and I’ve done both brands numerous times now. And in the future, if I have to get new brakes, or build a new bike…I’ll probably just use XT from the beginning. At least with these procedure mods above, my Guide R brakes don’t completely suck until that time comes.

If you have questions, please let me know. If you have helpful tips, add them to this thread!

Or if you’re a turd and just want to talk trash, go get a girlfriend and spend less time on the internet. Or use these tips to fix your brakes and go ride. Either way you’ll be a lot less of a turd.

Posted: Jan 27, 2020 at 10:21 Quote
I just bought xt brakes and locked up the sram in the box. Much easier.

Posted: Jan 28, 2020 at 11:09 Quote
MLeier wrote:
Just a thought though, rather than open up the screw at the lever to let some out which could make a mess, couldn't you just open the bleeding edge port again while applying enough pressure to the syringe to just allow a bit of fluid to come back out? Is there a reason why this wouldn't be a good idea or wouldn't work? Thanks!

Doesn't seem like slabshaft is too active here so I can give you my opinion based on experience. The method of burping the lever port screw if you've over-pressurized the system is probably the best way for micro-adjusting the pressure. Especially since you can't do this as easily on the bleeding edge caliper port when the wheel is re-mounted. But as you said it's messy and causes fluid to leak out on the lever.

I've also successfully re-opened the bleeding edge port when I over-pressurized and was able to release some of that pressure back into the syringe, and then quickly tighten up the port. I then re-squeeze the lever with all ports closed to check the difference that made, and just based on lever feel you can get it pretty close to optimal pressure. The only thing I'd say is to watch out for air bubbles at the caliper syringe. This is really important. When you re-open the bleeding edge port to pressurize the system, you have to hold the syringe vertically to make sure all of the air is at the top of the chamber and not at the port. And you have to be vigilant with doing this if you are re-opening to release or increase pressure at the caliper. Hope that helps.

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