[manhattanprjkt83]

Quick brake question for everyone…

I have a set of shimano XTR Trail levers paired with SAINT m810 calipers…Just set them up last weekend and did a fresh bleed. The front is working absolutely perfectly but the rear is another story.

I use a syringe to bleed from the caliper up and just push the fluid out of the lever. For whatever reason my rear brake is pumping up so bad that the lever wont move after a few runs and the brake is actually dragging.

I even through the syringe back on the caliper and gave the lever a squeeze to force a bit of fluid out with zero result…

Can anyone help here?

 

[jonKranked]

try an off-bike bleed, setup your lever to be directly above your caliper (i clamp a spare handlebar in my work stand and attach it to that). work the lever during the bleed, and i also flick the caliper and line.

have you checked the piston in the caliper? i know its brand new; might be faulty.

edit nvm, just re-read. open up the master cyclinder cap and work some fluid out. are the new ones still using the bladder insert design?

 

[Nick]

I had the same problem setting up a rear M810 brake.

In my experience, when pushing fluid up to the MC you have to do it REALLY slowly or the oil takes air from the syringe along with it. I got frustrated and re-filled from the MC with the caliper bleed nip open and a clear tube on it, slowly filled from the top and pumped the lever until fluid showed at the tube, closed everything up and it was perfect.

FWIW I never had any issue bleeding from the caliper up with any other Shimano brakes that I own.

edit: reading comprehension is fun. I thought you were getting air.

 

[jonKranked]

another question... how fresh is the mineral oil you're bleeding with? I've heard that funky things can happen to it as it ages.

 

[Sandwich]

I always bleed mine top down and have little problems. Fill the resi, CAP IT, then squeeze and release just like an auto brake. Has worked fine, I use pentosin chf11 or whatever.

I say "little" because my brakes have a tiny bit of air in the lines after sitting on the shelf for a season and not being rebled. Plus, I have no pad material left....

 

[manhattanprjkt83]

thanks for the replies everyone. Here is the story with the setup, i had the m810 levers but thought they sucked then they started leaking so i had them replaced with XTR trails so the calipers are half a season old and the levers are brand new.

To install the levers i just pulled the cables switched the lever then did a bottom up bleed to fill the lever...

To be fair the rear saint was tight before but it has reached a new level there is some good info in here. Like others i have been doing shimano this way for >5 years always worked so i was a bit lost.

 

[manhattanprjkt83]

another question... how fresh is the mineral oil you're bleeding with? I've heard that funky things can happen to it as it ages.

i guess its pretty fresh...straight out of the jug but it has been open for a long time.

 

[manhattanprjkt83]

edit: reading comprehension is fun. I thought you were getting air.

i have litterally drawn so much fluid out of the brake trying to losen it that it shouldnt even work...that is what has me stumped...starting to worry about the caliper.

 

[IH8Rice]

i guess its pretty fresh...straight out of the jug but it has been open for a long time.

thats not too fresh then

 

[kidwoo]

thats not too fresh then

Does it get moldy?


I've seen gatorade that color get moldy. Takes a while though, you have to really work at it.

 

[IH8Rice]

Does it get moldy?

 

[jonKranked]

i guess its pretty fresh...straight out of the jug but it has been open for a long time.

how long is long?

i don't remember the exact details, but i recall reading something somewhere that the thermal expansion properties get wonky as the mineral fluid ages/degrades (and breaks down or something), which is why its recommended to bleed them at least annually whether they need it or not.

 

[Uncle Cliffy]

Do you have the funnels that the new levers use for bleeding?

 

[manhattanprjkt83]

i dont have the funnel, that is actually why i need to do them caliper up...

the fluid has been sitting around my house probably been open for 6 months...but with the cap on...didnt think it was an issue.

 

[jonKranked]

i dont have the funnel, that is actually why i need to do them caliper up...

the fluid has been sitting around my house probably been open for 6 months...but with the cap on...didnt think it was an issue.

if its 6 months then that's not it. i'm talking more like 2-3 years.

 

[manhattanprjkt83]

i guess with the system under filled at this point what the hell could cause it to pump up to that point? sitting in my house the brake feels great but after a run or 2 it is literally completely frozen...

 

[jonKranked]

i guess with the system under filled at this point what the hell could cause it to pump up to that point? sitting in my house the brake feels great but after a run or 2 it is literally completely frozen...

water in the system?

 

[manhattanprjkt83]

possibly i guess...im going to try another full bleed and see how it goes...

 

[jonKranked]

since your caliper is used, might be worth taking it apart and cleaning it.

 

[TWeerts]

if your doing the push fluid all the way through method, why not push excess fluid through the system? im thinking it may clear out any contaminants like water/air/deposits?

just a thought...

 

[kidwoo]

I'm more curious to hear how mineral oil breaks down/degrades/absorbs contaminants while sitting in a closed bottle.

 

[IH8Rice]

I'm more curious to hear how mineral oil breaks down/degrades/absorbs contaminants while sitting in a closed bottle.

is his bottle still hermetically sealed like it is when brand new?

 

[manhattanprjkt83]

I'm more curious to hear how mineral oil breaks down/degrades/absorbs contaminants while sitting in a closed bottle.

as am I...I have run the old saints for 3 years without a bleed and zero performance change...

 

[manhattanprjkt83]

is his bottle still hermetically sealed like it is when brand new?

screw on cap

 

[manhattanprjkt83]

if your doing the push fluid all the way through method, why not push excess fluid through the system? im thinking it may clear out any contaminants like water/air/deposits?

just a thought...

this is my next step

 

[IH8Rice]

screw on cap

screw on cap ≠ hermetically sealed

 

[jonKranked]

I'm more curious to hear how mineral oil breaks down/degrades/absorbs contaminants while sitting in a closed bottle.

breaks down over time due to heat. this is accelerated when in use in a brake system, but can also occur gradually over time even at ambient temperatures (i'm talking more like ~5 years as opposed to ~6 months, which is why i asked how old it was). a quick google also indicates that exposure to certain spectra of light can cause it as well.

 

[jonKranked]

as am I...I have run the old saints for 3 years without a bleed and zero performance change...

i didn't bleed mine for a little over two years at one time... difference wasn't really perceptible, but the fluid that came out was clear, not red like shimano's fluid normally is. it did feel a touch better on a fresh bleed (og saints, xt levers)

 

[kidwoo]

breaks down over time due to heat. this is accelerated when in use in a brake system, but can also occur gradually over time even at ambient temperatures (i'm talking more like ~5 years as opposed to ~6 months, which is why i asked how old it was). a quick google also indicates that exposure to certain spectra of light can cause it as well.

Yeah I get all that, but that's not relevant to sitting in a bottle in a garage. It's oil, not dot fluid, and not getting subject to insanely high heat or uv rays. Opened or not, that shlt lasts a LONG time with no change.

Longer a span than shimano has made brakes worth a damn at this point.


It's actually one of the biggest reasons I use shimano brakes.


edit: definitely noticed the loss of color after a while. That's pretty much what I use as a barometer for any sort of compositional change. Either that or mold.

 

[pillete]

thanks for the replies everyone. Here is the story with the setup, i had the m810 levers but thought they sucked then they started leaking so i had them replaced with XTR trails so the calipers are half a season old and the levers are brand new.

To install the levers i just pulled the cables switched the lever then did a bottom up bleed to fill the lever...

To be fair the rear saint was tight before but it has reached a new level there is some good info in here. Like others i have been doing shimano this way for >5 years always worked so i was a bit lost.

Sorry to derail your thread, but i just want to know if you had to get new brake lines to make it work with the XTR Trail levers or were you able to just use the lines on your saint calipers?

 

[manhattanprjkt83]

Sorry to derail your thread, but i just want to know if you had to get new brake lines to make it work with the XTR Trail levers or were you able to just use the lines on your saint calipers?

no problem man...nope the M810 fittings fit right on the XTR Trail levers...Honestly the m810's blow in my opinion but 2 things to call out:

- the rubber hose covers do not really sit on the XTR lever that well.
- XTR Trails arent as long as the Saints if they were much shorter it would be a problem (I am a 2 finger guy)

hope that helps, took me 30 min to swap levers the new XTR's really are art.

 

[Huck Banzai]

Whats the weight savings? Ive become a w8-weanie to an extent. Also wouldnt mind improved performance, and bling is always welcome these days. I can blame going slow on wanting people to see my shinystuff.

 

[slyfink]

i had the same problems with my Saints but chalked it up to my line being crushed by my stanchions. i'm having the line replaced now. and will report back after my first ride on them. However, I'm going to presume you've already looked at the state of your brake lines, so i'm not sure how much help this this will be...

on a side note, and let me know if I should start a separate thread for this, i have just received one of my new XT brakes (M785) from CRC. They didn't ship both together as they are back ordered on the front brake. However, they are set up uk-style - or moto style) and I'm going to have to swap the lines and levers. Having never done this myself, how big a job is it, and would getting that little funnel kit be worth it? I will say that the new levers look beautiful... mmmm shiny!

 

[MarkDH]

Yeah I get all that, but that's not relevant to sitting in a bottle in a garage. It's oil, not dot fluid, and not getting subject to insanely high heat or uv rays. Opened or not, that shlt lasts a LONG time with no change.

Yeah I'd agree with that. My guess is that the recommendations to change mineral oil every so often are due to breakdown of additives rather than the oil itself. Probably explains the loss of colour in Shimano stuff over time. Sitting in a screw top container in a shed somewhere, I can't imagine much if any breakdown of the base mineral oil occurs, it's pretty stable stuff. It won't pick up significant quanitites of water either, much less than PEG based fluids.

 

[jonKranked]

Yeah I get all that, but that's not relevant to sitting in a bottle in a garage. It's oil, not dot fluid, and not getting subject to insanely high heat or uv rays. Opened or not, that shlt lasts a LONG time with no change.

Longer a span than shimano has made brakes worth a damn at this point.


It's actually one of the biggest reasons I use shimano brakes.


edit: definitely noticed the loss of color after a while. That's pretty much what I use as a barometer for any sort of compositional change. Either that or mold.

Yeah I'd agree with that. My guess is that the recommendations to change mineral oil every so often are due to breakdown of additives rather than the oil itself. Probably explains the loss of colour in Shimano stuff over time. Sitting in a screw top container in a shed somewhere, I can't imagine much if any breakdown of the base mineral oil occurs, it's pretty stable stuff. It won't pick up significant quanitites of water either, much less than PEG based fluids.

short and long term stability of the mineral oil would depend on what the base hydrocarbon structure is, which i don't know, and doubt shimano will tell us (just as an example, there are CH structures that are susceptible to bacterial degradation). mineral oil is also more susceptible to temperature fluctuations - which is why my brakes feel sluggish when i ride in below freezing weather.

in regards to water, mineral oil is non-hygroscopic. any water that gets into the system won't get absorbed like DOT fluid, and will settle at the bottom. IE in the caliper, where it can boil under use and cause drag - which may be the case in manhattan's problem - so it might be worth completely draining the system.

 

[MarkDH]

short and long term stability of the mineral oil would depend on what the base hydrocarbon structure is, which i don't know, and doubt shimano will tell us (just as an example, there are CH structures that are susceptible to bacterial degradation). mineral oil is also more susceptible to temperature fluctuations - which is why my brakes feel sluggish when i ride in below freezing weather.

in regards to water, mineral oil is non-hygroscopic. any water that gets into the system won't get absorbed like DOT fluid, and will settle at the bottom. IE in the caliper, where it can boil under use and cause drag - which may be the case in manhattan's problem - so it might be worth completely draining the system.

Mineral oil doesn't have a single structure though, it's a mixture of a variety of alkanes of a certain length/weight. You can burn them, and perhaps they undergo enzymatic degradation like you say, but sitting in a reasonably well sealed container they are definitely at the more stable end of the spectrum. I'd happily use stuff that had been sitting round for a few years.

Anyway, back to the problem at hand, would water cause the issue the OP is having? Surely if it vapourised it would feel more like air in the system, rather than locking the lever out solid? Just a thought.

 

[jonKranked]

Mineral oil doesn't have a single structure though, it's a mixture of a variety of alkanes of a certain length/weight. You can burn them, and perhaps they undergo enzymatic degradation like you say, but sitting in a reasonably well sealed container they are definitely at the more stable end of the spectrum. I'd happily use stuff that had been sitting round for a few years.

well yea, that was sort of my point, without knowing the composition we can't know how it'll perform. alkanes encompasses a very large range of hydrocarbons, similar to how polyethylene is a large range of polymers. using the term generically doesn't give you a lot of details on what exactly the structure/composition/density/performance traits will be.

in regard to sealed containers, a screw on closure is certainly NOT fairly well sealed. it'll keep out solid particulates, but gases & moisture are most definitely able to get through. i did a lot of studying and testing regarding this when I worked in the pharma industry. this is why when you buy a product in a bottle that's sensitive to moisture or certain gases it has an induction sealed foil on it.

Anyway, back to the problem at hand, would water cause the issue the OP is having? Surely if it vapourised it would feel more like air in the system, rather than locking the lever out solid? Just a thought.

yea, water could cause it. water's desnity is higher than mineral oil, so it'll settle in the lowest point, the caliper, which is where the highest heat generation occurs. the heat will cause the water to expand, which will increase the pressure in a closed system, if it gets hot enough it'll boil.

 

[IH8Rice]

in regard to sealed containers, a screw on closure is certainly NOT fairly well sealed. it'll keep out solid particulates, but gases & moisture are most definitely able to get through.

which is what ive been saying.

 

[MarkDH]

well yea, that was sort of my point, without knowing the composition we can't know how it'll perform. alkanes encompasses a very large range of hydrocarbons, similar to how polyethylene is a large range of polymers. using the term generically doesn't give you a lot of details on what exactly the structure/composition/density/performance traits will be.

Hmm, I suppose density and boiling point will vary if you compare oils that are at opposite ends of the length/weight range (whilst still able to be classed as mineral oil). I thought we were only talking about stability over time though, in which case I'd still maintain that what is likely to be a mixture of straight chain alkanes, perhaps with some branched chain alkanes thrown in, is going to be pretty stable, even when exposed to air and moisture.

Still, this digression is detracting from this guys problem.

 

[kidwoo]

Still, this digression is detracting from this guys problem.

I just wanted to poke fun at the idea of 'old' mineral oil.

I agree, we've achieved that.



Back to ridemonkey: Buy some codes brah!! Best brakes evrrrr!!