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Saint 820 brakes inconsistent bite point - any fixes or solutions yet?

slyfink

Turbo Monkey
Sep 16, 2008
5,923
1,672
Ottawa, Canada
Udi and Woo... I've read and re-read the later part of this thread, but I'm still not sure I've captured the essence of the problem with the XTs. I have XT on my trail bike, and for the life of me can't get a good bleed on the rear brake. I've tried many times, even taken the entire brake-line-caliper assembly and hung in vertically (or rather I had the shop do it...) to get the bleed right. It seems to be good for a day or two, then it's back to the same problem which is: inconsistent bite point (though never a total loss of power) and loss of power (I can't even do a skid on snow). Am I right in assuming it's an issue with the seals at the caliper? Could I just buy a new caliper and stick it on there?
 

kidwoo

Celebrating No-Pants Day
Aug 25, 2003
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Now we know what happened to Gwin in Leogang.
Yeah when that happened, half the shimano brake owners were sitting there going 'yup, I know that one' :D


Udi and Woo... I've read and re-read the later part of this thread, but I'm still not sure I've captured the essence of the problem with the XTs. I have XT on my trail bike, and for the life of me can't get a good bleed on the rear brake. I've tried many times, even taken the entire brake-line-caliper assembly and hung in vertically (or rather I had the shop do it...) to get the bleed right. It seems to be good for a day or two, then it's back to the same problem which is: inconsistent bite point (though never a total loss of power) and loss of power (I can't even do a skid on snow). Am I right in assuming it's an issue with the seals at the caliper? Could I just buy a new caliper and stick it on there?
I'm not sure Udi or I know the definitive answer either but I realized that my calipers leak for a fact last summer when my bike sat around for a few weeks. Only on one set though. That set goes blank. The other set never does. To me that's a source of air in the lines.

It may not the the ONLY source though. I've never had brakes that get as hot as these do so there might be some water vapor in there boiling....maybe some isolated pockets of the oil off-gassing... Or it's just really hard to keep the system sealed.


But shimano needs to figure this shlt out. If these brakes were literally flawless, it would be a nail in the coffin for all other brakes IMO. Dot fluid sucks and the best incarnations of those seem to the be the formulas....and you won't be finding those for around 100 bucks a side.
 
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Udi

RM Chief Ornithologist: “I Brake for Birds”
Mar 14, 2005
4,738
843
I think there's a huge tendency to blame the bleed when the brake is at fault, I'd definitely start by not blaming that / yourself. I read way too many threads where there is an actual problem with the brake and there's 100 replies detailing bleed methods.

I think you can split up the known issues with that brake into 3 categories:
a) Leaking caliper seals
b) Master cylinder issues
c) Leaking hose joints

I think you can rule out the hose pretty easily, but what I've seen very commonly on these is not being able to lock them up - it's almost always caused by the leaking caliper seals contaminating the pads. A good test is to clean around the pistons and seals thoroughly with alcohol, and go for a dusty ride with some hard stops. Inspect for moist dust around seals. Not being able to lock up is almost always a contamination issue, force generated at the piston is not dependent on bleed unless you run out of lever throw (MC bottoms out or lever hits a physical stop).

The inconsistent bite point issue is lever related I'm quite sure, as one particular set here leaks at the caliper but has zero bite point issues, the brake functions normally. You could try playing with the lever throw adjuster (that seemingly does nothing) in case it has some effect on it.

Unfortunately I have a feeling you may be in a scenario where both lever and caliper are faulty, I'd recommend just buying a complete brake as they are very cheap on Wiggle or CRC. I'd go with an SLX personally as they eliminate one point of inconsistency by having a fixed throw screw setting, not sure if that helps anything but Steve M suggested it may in another thread. They're also cheaper and functionally the same otherwise. For whatever it's worth, I have a set of the new SLX that have been trouble free so far, but am not confident that's universal.
 

motomike

Turbo Monkey
Jan 19, 2005
4,587
0
North Carolina
I think there's a huge tendency to blame the bleed when the brake is at fault, I'd definitely start by not blaming that / yourself. I read way too many threads where there is an actual problem with the brake and there's 100 replies detailing bleed methods.
Agreed. The problem is that the issue with the master cylinder is really hard to replicate on purpose. From what I have been told, most of the time it happens when the lever is set up really close to the bar with very little lever throw before the pads bite the rotor. And given my own experiences with this issue, that seems to be the case. I changed my setup a little bit and haven't had any problems since.

There is no denying the air issue though. No idea where it is coming from, and no signs of fluid actually leaking out on mine, but air definitely does get in somehow. Luckily that doesn't negatively affect shimano brakes the way it does others. I just top it off every once in a while and its fine.
 

ButtersNZ

Monkey
Jun 6, 2013
176
10
Mine had this issue, having had to pump them up a bit before runs and even move the lever position out sometimes. My shop fitted goodrich braided hose and bled them. No problems since.
 

Da Peach

Outwitted by a rodent
Jul 2, 2002
12,574
1,888
North Van
My rear XTR just started to have the bite point go all inconsistent-like. So annoying.

I did a full bleed, and no change. Even more annoying.

Shop says they're going to try to get me a warranty, so we'll see what comes of it. "about 2 weeks". Crap.

Good thing I just bought a set of Deores for my commuter...

I'll use this opportunity to also send my fork back for a warranty replacement of the CSU, "Cryo creak". This will be my second replacement.

kinda frustrating.
 

Udi

RM Chief Ornithologist: “I Brake for Birds”
Mar 14, 2005
4,738
843
I should update that the SLX I mentioned previously as reliable recently developed a leaking caliper seal similar to all the XTs here. Should have bought a RUX.

I am currently in the process of converting all my bikes over to Formula, my DH bike having run the same pair of The Ones for the last 4 years. Who would have thought that the Italians would prove most reliable?
 

djjohnr

Turbo Monkey
Apr 21, 2002
1,932
568
Northern California
I guess the good news is I read this before I opened my new set of Saints. The bad news is now I have to ship them back across the pond. I thought this is what I was getting away from by moving to Shimano from Avid damnit.
 

kidwoo

Celebrating No-Pants Day
Aug 25, 2003
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I guess the good news is I read this before I opened my new set of Saints. The bad news is now I have to ship them back across the pond. I thought this is what I was getting away from by moving to Shimano from Avid damnit.
Just ride them. They don't all do it. I've a pair of xts that leak, one pair that were flawless, saints that don't, and then a pair of saint calipers/zee levers that did. Then some SLX ones that only go to the bar right after backflips (totally serious, it's terrifying).

What's that, 50/50? You gotta chance man! A chance! :D
 

Gallain

Monkey
Dec 28, 2001
183
43
Sweden
Just ride them. They don't all do it. I've a pair of xts that leak, one pair that were flawless, saints that don't, and then a pair of saint calipers/zee levers that did. Then some SLX ones that only go to the bar right after backflips (totally serious, it's terrifying).

What's that, 50/50? You gotta chance man! A chance! :D
Had a Saint front caliper leaking after an employe trained bleeding and rebuilding it (He somehow manged to crack a piston). After I fixed that I haven't really had any problems with my saints, some inconsistency in lever throw but nothing much. Never any problems with my XT or SLX brakes. None of my friends on Shimano brakes have any problems but almost all on avids have issues.

(The irony is that on my new job I sell Sram/avid and not shimano)
 

kidwoo

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That inconsistent bite point is a symptom.

It seems like there's some sort of hard lean involved every time I've had one that just brings the lever to the bar.

I'm not gwin but that WC run is just so typical of what happens.......hard leaning turn, then next time you grab the brakes....nothing. I've had that exact thing happen and so has a pretty significant group of friends I ride with (all mechanics who really figured this out for me a few years ago).

That's even kind of consistent with the slx ones I have on my dirtjumper. Always worked fine and then I started practicing backflips on foam and mulch. Literally every single time, first grab, nothing there. That motion spins a bike sending fluid to the calipers and exacerbating any bubbles in the lever, just like a hard leaning turn. What gets me though is that it seems like hard g-outs would do the same thing. I haven't noticed that one.
 
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Wetbed0

Chimp
Dec 17, 2013
73
2
Colorado
That fits with my experience with xt's, demo bike felt great when I left the shop, but a night of laying on its side in my car (not leaving it on the rack overnight) it took a few minutes of pumping to get them feeling right the next day. Good after that, and they were find the next time I took the bike out, nut just odd.
 

jstuhlman

We noticed.
Dec 3, 2009
9,516
4,260
Cackalacka du Nord
every time i flip the bike over with my xt's...levers to the bars when i turn it back. a few squeezes, it's all fine. i don't do backflips. it's never happened under any other circumstances, no matter how leaned, g'd, gnar. i can live with it, 'cause they've been mint for three years otherwise.
 

kidwoo

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I remember the video TWR and their sponsors wanted you to see. I also remember this:

They obviously worked up to that point on the track......and in the pits and that morning.

Like everyone in this thread has said, air gets in there, either through something leaking or from an insufficient bleed. His had a leak/seal breach. But how it shows up is summed up exactly with what happened to him. Damaged piston or not, when these things aren't completely air free, that's what they do. That's all I'm saying. They work just fine, even with air in them so you'll think they're fine, but then that happens. And it's just really difficult to get a flawless bleed with them sometimes. Much less the leaky piston thing and all the other reasons for bubbles.
 

Nick

My name is Nick
Sep 21, 2001
14,838
3,251
behind you, don't wait up.
3 sets of XTs over the years. No issues.
M810s, this was a constant issue.
M820s, front caliper leaking right out of the box, replaced under warranty, no issues since.

To add, I don't do backflips.
 

Tmeyer

Monkey
Mar 26, 2005
586
1
SLC
Do you notice it more from the rear? I've never had my 820's go to the bar but definitely have had some weird lever throw starting into a few high speed bermed corners. Never from the front though.


I remember the video TWR and their sponsors wanted you to see. I also remember this:

They obviously worked up to that point on the track......and in the pits and that morning.

Like everyone in this thread has said, air gets in there, either through something leaking or from an insufficient bleed. His had a leak/seal breach. But how it shows up is summed up exactly with what happened to him. Damaged piston or not, when these things aren't completely air free, that's what they do. That's all I'm saying. They work just fine, even with air in them so you'll think they're fine, but then that happens. And it's just really difficult to get a flawless bleed with them sometimes. Much less the leaky piston thing and all the other reasons for bubbles.
 

antihero

Chimp
Jul 3, 2008
10
0
the problem i have with my Zee's is that under really fast rough terrain they will loose all the lever stroke and just lock up the wheel while only moving the lever a fraction of its stroke.
 

kidwoo

Celebrating No-Pants Day
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Do you notice it more from the rear? I've never had my 820's go to the bar but definitely have had some weird lever throw starting into a few high speed bermed corners. Never from the front though.
Both.

The fun part is that it depends on which way you lean. That's what makes me think there's air around the caliper that comes into play with some g-forces.
 

slyfink

Turbo Monkey
Sep 16, 2008
5,923
1,672
Ottawa, Canada
I figure I'd add my experience to this thread as I finally figured out what my problem was (see post #121). Turns out I had a leaky hose. Tiny little stress fractures that were barely visible. I was about to send the brakes to Shimano for warranty when the shop noticed the leaking (after at least 6 bleeds over two years). Replaced the hoses, and no more problems, at least for about three months. Now I'm getting the lever to the bar thing when I flip the bike or even lay it on its side. Once you pump it a few times, it works perfectly fine again.

My mechanic told me it's pretty much impossible to get all the air out of the system, and that Shimano's system seems to deal with air the best. except when you flip the bike or something. So I guess that means that I'll have to just hunker down and get familiar with bleeding the things, and hope that each bleed will be good for a few months. I may also try braided steel hoses.
 

kidwoo

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Heh......Now that it's cold the xts on my trail bike are now doing the opposite of what they usually do......bite point magically occurs further from the bar now.

SCIENCE! :rofl:
 

rscecil007

Chimp
Oct 18, 2007
48
7
Random Bite Point Generator - good one. I think the cold temps affect Shimano brakes more than most realize. I think that's probably what was going on with my Saints when I started this posted ages ago. It was late fall and colder when both sets started acting up. All summer they'd been fine.

FWIW, that was the first winter I'd been on Shimano brakes, and I really had no idea the cold would affect them, or mineral oil, for that matter. No idea how I didn't know that, but so it goes.

My XT's and XTRs have done it in cold temps, and so do my new brakes (XTR race levers with Saint calipers.)
 

kidwoo

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I'm still waiting for mine to quack like a duck and spit out 100 dollar bills.

It's no more random than what they already do.
 

6thElement

Schrodinger's Immigrant
Jul 29, 2008
4,422
2,172
I know it sounds dumb but I'm thinking of trying Guide's for some new brakes to avoid the possible bite point issues with XT and that the levers are likely too short to work with grip shift.
 

kidwoo

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They're not too short to work with grip shift.

Ask me how I know!


I'd rather buy formulas than anything sram makes.
 

djjohnr

Turbo Monkey
Apr 21, 2002
1,932
568
Northern California
I know it sounds dumb but I'm thinking of trying Guide's for some new brakes to avoid the possible bite point issues with XT and that the levers are likely too short to work with grip shift.
I have brand new sets of Saints and Guides sitting on my bench right now; I think I'm going to send the Saints back based on this thread. The Guides are super cheap at Jenson - $100 for RSs. If they don't work out I'll try Hope E4s next.
 

kidwoo

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I have brand new sets of Saints and Guides sitting on my bench right now; I think I'm going to send the Saints back based on this thread. .
Pssh.......fuck this thread. They're still the best brakes ever in the history of ever. (totally serious, they still blow everything else away).

Go ride them.