Unanswered Sram Guide RE Bleeding Woes!

[lolp]

Hi. I've read about Guide brake bleeding problems but never experienced them until now.

To cut a long story short(ish) my lbs replaced the whole rear brake - lever caliper and hose after issues with the original one (which may not have been necessary but thats a different story). After two rides the lever was spongey and had much travel before having any effect and even then the stopping power was low. So I bled the brakes and the lever felt solid with little travel so I rode again but by the end of that ride the lever was spongey I had to pull almost to the bar to get only a fraction of the stopping power I started the ride with. I can't find a leak anywhere visible. so I bled them twice again - even taking the caliper off on one bleed so the bleed port was at the highest point. Same result - end of one ride and a mushy rear brake. I also bled the front brake (once) in the same way and all is fine there. so I did it again and replaced the pads - same again but perhaps less so (not much). And each time I bleed them there seems to be no air in the hose but I'm pulling quite a lot of air out of the caliper in particular.

2 other points -
1. On the first bleed I had the lever set to 75mm from the front of the bars not centre so it was pulled further
2. The Guide RE has the old bleed port - not the bleeding edge technology.

So has anyone got any ideas what could be wrong or tips to improve the bleeding to give me a happy new year. Thanks.

 

[steve_sordy]

I'm no expert, but you must have a leak, probably at the calliper end.

 

[salko]

I had similar symptoms with my rear Code RSC brake. Long story short, it was a bad brake hose - inside pressure (white) layer of the hose was leaking, but because outside protective (black) layer was still undamaged there was no visible leak. When I pulled the brake lever the oil escaped between both layers and returned back in the system after I released the lever ...

 

[lolp]

Hi Salko. That was what my lbs diagnosed for my original brake so I replaced the whole lot just in case and now its happening again. Seems I am really unlucky? Any idea whether the innner hose is likely to be leaking where its connected to caliper/lever (seems most likely to me) or could it be anywhere?

 

[salko]

One question: at the rear brake caliper, on how many points/bolts you have the brake hose fixed to the rear swing arm before it goes into the frame?

 

[lolp]

Hi Salko. Its a 2019 Levo. There is one fixing - to the chainstay - there is a bolt on the inside of the seatstay which is unused. I'm not sure if it ever was used even before the lbs replaced the whole brake.

 

[salko]

Ok, then this is not the case with you ... I had hose fixed on 2 points/bolts and I think this caused the hose got kinked while rear wheel moved through the stroke ...

 

[lolp]

I must admit I had wondered whether feeding the new hose through the frame etc could be done easily without kinking it. I'll have to bleed each week before a ride until it goes back to lbs in the new year - they supplied and fitted ithe whole assembly so they can sort it out for me - if some 'bleeding' magic isn't the answer - which I doubt!

 

[Mikerb]

To confirm, the bolt on the chainstay immediately before the cable goes inside the chainstay is used...the bolt on the seat stay is not used.
Seems to me if you have the same problem both before and after the LBS replaced the caliper and hose then your problem is at the lever. You could make sure all bolts and banjos on the caliper and lever are tight enough........the mechanic may have left one loose enough to allow air in.
The only other reason I can think of that would let air into the system is a caliper piston moving out beyond its seal.......easy to do if you accidentally pull the lever with the wheel off.