Donal
Well-known member
The brake system 'breathes' though a port in the cover of the master cylinder reservoir. Every time the temperature changes the air expands or contacts and expels or draws in ambient air............
Rear Brake has no effect on 08 GenII
- Thread starter woodcycl
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Denver_FJR
Well-known member
Although there is a port in the cover, it's only there to prevent a vacuum lock as the rubber diaphragm contracts (fluid moving from the master cylinder to the slaves as the pads are pushed out due to normal wear). The system is sealed by the diaphragm.
RH, I've always been skeptical of the claim that moisture still makes it way into the system. Every "authority" I've come across claims moisture does make it way into the system and fluid must be changed. Considering the brakes necessity, I've always changed fluid regularly. I do appreciate the better brake response I get after changing fluid so there's something to be said for that.
RossKean
Well-known member
I can't see much, if any moisture making it in through the master cylinder cover. On the other hand, there can never be a "perfect" seal between the rubber seals and the metal piston in the MC or brake caliper. I have no idea how much moisture/humidity could be transferred per braking cycle (not much!) but there are an awful lot of braking cycles over the course of the year. (and a LOT more and longer clutch cycles which is probably why the clutch fluid looks worse than brake fluid after a couple of years)
It takes very little moisture to lower the boiling point of brake fluid but few of us ever run the brakes hard enough to boil the fluid. I am far more concerned about corrosion than boiling brake fluid. Also, the fluid gets contaminated by dirt making it past the seals and wear material from the rubber bits in the system. I change out the hydraulic fluids every year (or 2 at the most). Couple of bucks for fresh DOT 4 and an hour or so of my time - beginning to end.
It takes very little moisture to lower the boiling point of brake fluid but few of us ever run the brakes hard enough to boil the fluid. I am far more concerned about corrosion than boiling brake fluid. Also, the fluid gets contaminated by dirt making it past the seals and wear material from the rubber bits in the system. I change out the hydraulic fluids every year (or 2 at the most). Couple of bucks for fresh DOT 4 and an hour or so of my time - beginning to end.
ionbeam
2 FUN
If someone is serious about studying brake fluid condition I've got the place. Bring a lawn chair and note book and sit at any of the turn-outs between 1/2 to 2/3 the way down Mt. Washington in New Hampshire. You will have a steady supply of vehicles with smoking and flaming brakes to study. While the drivers wait for the brakes to come back or a tow truck you can interview them about their brake fluid maintenance and see if there is a correlation between age/miles/maintenance. You can sit on the other side of the road about 2/3 the way up Mt. Washington and study cooing system maintenance as the rolling geysers pull over.
Looking at the older cars that are over represented at the turn-outs I would think that brake fluid maintenance is a good thing. Follow Yamaha's recommendations, this is one place where caution is good. Your ABS metering block will like you too.
Looking at the older cars that are over represented at the turn-outs I would think that brake fluid maintenance is a good thing. Follow Yamaha's recommendations, this is one place where caution is good. Your ABS metering block will like you too.
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RadioHowie
I Miss Beemerdons!
Umm, Denver_FJR's reply below addresses this possibility of contamination...
You share my skepticism...
Don't anybody get me wrong...I don't believe brake fluid is "permanent" and should never be changed. I change mine as well, because it DOES get dirty, but this alleged moisture contamination due to exposure to the atmosphere simply doesn't make a whole lot of sense to me.
It comes down to this....if moisture can get in, then brake fluid can get out. The braking system is under a lot more pressure than atmospheric pressure, so atmospheric pressure loses every time. If "air" can get it, brake fluid can get out...and would on a regular, and messy, basis.
bwv
Well-known member
Water is "the universal solvent", can break down and/or penetrate almost any material or container over time, and is likely the single most destructive compund on this planet...
(it is also the single most blamed cause of brake fluid failure... I agree with the "how the hell does it get in there" too.. but everyone says...so it must be true...)
...but it's probably not the issue here... he's not near an ocean..and is it really that humid in Southern Indiana? (Really..is it? I don't know...)
That all being said... did the OP bleed his brakes? Any News?
It's been a week, you should be riding by now
(it is also the single most blamed cause of brake fluid failure... I agree with the "how the hell does it get in there" too.. but everyone says...so it must be true...)
...but it's probably not the issue here... he's not near an ocean..and is it really that humid in Southern Indiana? (Really..is it? I don't know...)
That all being said... did the OP bleed his brakes? Any News?
It's been a week, you should be riding by now
Au contraire!
Water evaporates at room temperatures. Brake fluid will not. It is the water vapor that we call humidity that is the issue with contamination of brake fluid. Glycol based brake fluids are hygroscopic, which means it has an affinity for water in any state. It will actually absorb the water vapor right out of humid air, no need for it to be in a liquid form.
Air is allowed into the upper reservoir via a vent to allow the fluid to be drawn down into the master cylinder. Yes, most have a flexible membrane of some type (typical rubber, which is semi permeable to air) to help keep any splashing brake fluid from getting out, but it is not a perfect seal to the air molecules.
Do people make more fuss over it than really necessary? Probably.
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ionbeam
2 FUN
RadioHowie
I Miss Beemerdons!
Okay...THAT makes some sense...humidity entering reservoir through the rubber bellows.
(says a person with a frozen ABS metering block)
SoCalFJR1300
Well-known member
woodcycl
Well-known member
Wow, so this topic really took off.
Okay, this is a Yamaha certified dealer with the same owners for years and years (just a new name after 30 yrs or so). They had a Yamaha certified tech work on it. And, I mentioned the fact that they are linked (this is a 2008 model Gen 2) and to go ahead and bleed both anyway and also the clutch as well.
I was told last Friday when I picked up the bike that the tech spent an extra 30 minutes being extra sure they did everything they could to ensure that bleeding the brakes wouldn't resolve the issue. Again, I'm not a mechanical guy and bleeding the brakes may be easy for some, but I have never done it and especially on a linked system where I continue to hear "be sure", etc. etc. etc. I'd prefer to have someone in-the-know handle it.
Yeah, I was a bit surprised that I needed a new rear master cyclinder. I looked them up online and the master cylinder alone isn't that expensive. But, I wonder how many additional parts i need besides just that one. I was quoted $156 for the part(s) alone and 1 hr @ $85 for labor. They are closed on Mondays so I plan on calling tomorrow to find out exactly which parts they are going to order and look them up myself. If there is more than a 10% markup, I'll order them myself.
I'll also talk to the service manager to find out and confirm that the guy working on the system absolutely was aware of how to bleed linked brakes on a FJR ... or not. And, be sure I have a warranty or guarantee on the work. I am NOT happy about having to spend $238 for to bleed front and rear brakes and a clutch .... and still not have working back brakes. I wish I was comfy handling it myself.
Okay, this is a Yamaha certified dealer with the same owners for years and years (just a new name after 30 yrs or so). They had a Yamaha certified tech work on it. And, I mentioned the fact that they are linked (this is a 2008 model Gen 2) and to go ahead and bleed both anyway and also the clutch as well.
I was told last Friday when I picked up the bike that the tech spent an extra 30 minutes being extra sure they did everything they could to ensure that bleeding the brakes wouldn't resolve the issue. Again, I'm not a mechanical guy and bleeding the brakes may be easy for some, but I have never done it and especially on a linked system where I continue to hear "be sure", etc. etc. etc. I'd prefer to have someone in-the-know handle it.
Yeah, I was a bit surprised that I needed a new rear master cyclinder. I looked them up online and the master cylinder alone isn't that expensive. But, I wonder how many additional parts i need besides just that one. I was quoted $156 for the part(s) alone and 1 hr @ $85 for labor. They are closed on Mondays so I plan on calling tomorrow to find out exactly which parts they are going to order and look them up myself. If there is more than a 10% markup, I'll order them myself.
I'll also talk to the service manager to find out and confirm that the guy working on the system absolutely was aware of how to bleed linked brakes on a FJR ... or not. And, be sure I have a warranty or guarantee on the work. I am NOT happy about having to spend $238 for to bleed front and rear brakes and a clutch .... and still not have working back brakes. I wish I was comfy handling it myself.
russperry
Well-known member
My problem happened on Day 2 of my 9 day trip through Colorado last year - I tried and failed at the rear caliper so gave up and rode the next 7 without any rear brake at all - I only recovered the rear with the front caliper trick after i got home. The biggest pain was when stopping on any uneven, dirty, gravelly turnouts where I was worried about tucking the nose. It also intimidated me off of trying some longish dirt tracks but that was probably a good thing
RaYzerman19
Go Wings!
It would initially seem unlikely you need a master cylinder, however let's say it's a possiblity. CheapCycleParts lists it for $106 and there is a rebuild kit for $30. One thing to verify also is that the rear brake pedal is not sticking, thus potentially closing off the port that allows fresh fluid in from the reservoir. And yes that bleeder on the front needs to be done first.
Now a little wrinkle, someone else reported here he couldn't bleed his rear brakes, and there was some speculation of blockage in the ABS system... don't know if that was true or worked out. I'd verify the master cylinder thing first, before going down that (expensive) road. You'd know if the master cylinder was OK if you could pump fluid out the rear caliper bleeder.
And not to hijack, but Ionbeam and Howie mentioned the metering block.... this is more related to the linked brake system than ABS, it and the proportioning valve are in line to the right front caliper for the linked brakes. Blockage in there wouldn't be a good thing for being able to bleed the front. If I interpret the FSM correctly, this does not affect whether the ABS is working or not, just the amount of fluid pressure going to the right front linked caliper.
Now a little wrinkle, someone else reported here he couldn't bleed his rear brakes, and there was some speculation of blockage in the ABS system... don't know if that was true or worked out. I'd verify the master cylinder thing first, before going down that (expensive) road. You'd know if the master cylinder was OK if you could pump fluid out the rear caliper bleeder.
And not to hijack, but Ionbeam and Howie mentioned the metering block.... this is more related to the linked brake system than ABS, it and the proportioning valve are in line to the right front caliper for the linked brakes. Blockage in there wouldn't be a good thing for being able to bleed the front. If I interpret the FSM correctly, this does not affect whether the ABS is working or not, just the amount of fluid pressure going to the right front linked caliper.
dj bill
Well-known member
waiting for the update woodcycl
rushes
Well-known member
I'll throw this out there again. My 08 needs the rear brake bled if it sits for more than a month.
No leaks, system fully bled both manually and with a pump.
Dealer buddy and every wrench I know can't figure it out.
Weird deal....
Pretty easy to bleed.
A lot of my bikes have a pre-ride ritual, so I don't stress about it...
No leaks, system fully bled both manually and with a pump.
Dealer buddy and every wrench I know can't figure it out.
Weird deal....
Pretty easy to bleed.
A lot of my bikes have a pre-ride ritual, so I don't stress about it...
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RossKean
Well-known member
I would suspect a very minor leak at the bleeder nipple or a banjo fitting. Can't be too bad or you would see brake fluid dripping somewhere.I'll throw this out there again. My 08 needs the rear brake bled if it sits for more than a month.No leaks, system fully bled both manually and with a pump.
Dealer buddy and every wrench I know can't figure it out.
Weird deal....
Pretty easy to bleed.
A lot of my bikes have a pre-ride ritual, so I don't stress about it...
RaYzerman19
Go Wings!
Let's back up a bit and ask, what symptoms are causing you to bleed after a month?
rushes
Well-known member
I didn't intend to hijack the thread, but soft pedal, and I might get a bubble or 2 out of the front usually.
The only thing I can guess is maybe a pocket in the system up high that just won't pump through.
RaYzerman19
Go Wings!
No prob, I thought it might apply to the OP's issue too....... I'd suggest bleeding the old fashioned way (ie., no vacuum bleeding) with Speed Bleeders or stock bleeders with teflon tape on the threads. You could try the old trick used with the fronts by putting an elastic band to hold the lever down overnight, but for the rears I don't know if a bubble would travel back to the master or not.
There could be something going on inside the master cylinder, might be worth spending the few bucks for the rebuild kit and have all new rubbers in there.
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Yeah, that Ty-Wrap trick works better for the clutch and the front without ABS. When you add ABS there is a loop to get to the ABS hydraulic block that acts like a P trap in reverse and traps air.
