[Quarashi]

I use my XT's for DH racing (hence this forum ). They' relatively old, the first generation servo waves. I used them for quite awhile without bleeding, about a year, Over the past few months I noticed they've been really weak on the power side of things (relative to before). I've bled them again and again and although they feel better after the bleed, it doesn't last long and it never feels nearly as strong as they once were.
I though I needed new brakes until I tried a bike of a friend with newer XT's and I had forgotten just how powerful these brakes could be.

A friend of mine has almost the exact same problem with his Saints.

Anyway, does anyone have any advice they could give on what I could do to revitalize my brakes? I know it has the potential to give me the power that I need (I thought I'd have to get saints) and I'd rather not spend $$$ on new brakes. I might just be incredibly unlucky and have had terrible bleeds on after the other from different mechanics (I know I should get some bleeding tools) but I highly doubt the problem is the bleeding. From what I know it could be bad pads (stock Shimano XTR resins) or just worn out rotors that have gotten smooth over the season.

Is there anything else I can do to resurrect my brakes before I decide to buy new ones?

Thanks!

 

[rich.grandzol]

It could be the square-edged seals that sit between the pistons and the caliper bodies.

Try cleaning the pistons themselves:

http://www.shimano.com/publish/cont...wnloadFile.html/04) Brake Reset Procedure.pdf

If that doesn't work, it might be the square-edged seals have degraded. That happened to my first-gen Saints (after running them for 5 seasons without bleeding!) Now they are my backup brakes as they still work, just not as powerful.

 

[SHIVER ME TIMBERS]

stupid questions but here goes

are you using the stock shimano minerial oil

is it both brakes are just one (if it is one then replace the brake line...you might of kinked it or have a small hole

 

[Quarashi]

It could be the square-edged seals that sit between the pistons and the caliper bodies.

Try cleaning the pistons themselves:

http://www.shimano.com/publish/cont...wnloadFile.html/04) Brake Reset Procedure.pdf

If that doesn't work, it might be the square-edged seals have degraded. That happened to my first-gen Saints (after running them for 5 seasons without bleeding!) Now they are my backup brakes as they still work, just not as powerful.

Thanks Rich I'll check it out. If the seals have degraded are they easily replaceable? Are these seals shimano only or can I get them at a supply shop?

SMT, I'm using stock mineral oil but the cable has taken quite a few snags-on-branches. Ever since it's first bleed it seems to need bleeding much more frequently. Does this sound like a seal problem?
Also regarding cables, do they "wear out" perse. These have had plenty of DH miles behind them.

Thanks.

 

[roel]

Thanks Rich I'll check it out. If the seals have degraded are they easily replaceable? Are these seals shimano only or can I get them at a supply shop?

SMT, I'm using stock mineral oil but the cable has taken quite a few snags-on-branches. Ever since it's first bleed it seems to need bleeding much more frequently. Does this sound like a seal problem?
Also regarding cables, do they "wear out" perse. These have had plenty of DH miles behind them.

Thanks.

On the same boat, am using them for few months only (almost new) , one piston (one side only) dont return at home position(??). Bled once and been ok for about few rides,and then same problem again...kinda weird, its new..Im pushing them back with a flat screw only to come out again...

 

[Quarashi]

On the same boat, am using them for few months only (almost new) , one piston (one side only) dont return at home position(??). Bled once and been ok for about few rides,and then same problem again...kinda weird, its new..Im pushing them back with a flat screw only to come out again...

Correct me if I'm wrong but I don't think the pistons are supposed to go back all the way. I think they're supposed to contact the rotor then move a little bit back and it's their way of automatically compensating for pad wear or adjusting for rotor spacing. I don't know, mine seem to do that and it's my first pair of hydro brakes. Yours rub the rotor constantly?

 

[spxoo]

when I first got my XT's I ordered some special resin pads that are for the 8" rotors. They wore out and I have some other resin pads. I just got the brakes this season so the pads wore out pretty fast but the part numbers on my old pads were different from the ones Im running now. I think the ones I have now are a little less powerful and a little more noisey, it's hard to tell, the new ones were a little bit cheaper too.

I have also had my pistons get sticky on those brakes too, and it makes the lever fell all crunchy and the pads not retract properly. but it's especially easy fix on the shimanos, take the pads out and pull the lever so the pots come out more than get some mineral oil all over the exposed pots than push the pots back in and repeat a couple times and clean with alcohol. This is a problem I have never had with my old shimanos which I have literally never done anything to.