Brakes failed

[RossKean]

I would say the rear disk is done. The scoring looks deep. The original thickness is not all that much greater than minimum spec., although enough to last a couple hundred thousand miles if not abused. Having been heated enough to boil the fluid and burn the paint off the hubs as per the photo, they are no longer safe in any case, especially with the scoring. Have a very close look at the right front disk as well.

You seem quick to condemn the design, but the fact is that the rear brake was badly cooked - either due to a stuck pedal or rider error. IMHO, you should have figured out there was a problem long before the front also heated up enough to boil that fluid as well - epecially with the observed greatly reduced available power in higher gears. The FJR has brakes at least as good as any motorcycle I have ridden. Utterly reliable, in my experience. I suspect that the brake fluid must have absorbed a lot of water - DOT4 does not boil readily unless badly contaminated, except under extreme conditions.

Shouldn't be a question of trusting the bike, but if you want to blame it for your error in riding, maintenance or judgement, then I wish you better luck with your next bike.

 

[SkooterG]

Lower your rear brake pedal a notch, maybe two on the shaft. Common to do on the FJR as in stock position it feels high.

And I'll ask again.......How old was the brake fluid in there?

 

[Oldjeep]

Are there pads left? That wear is a lot further inboard than the pads should reach. In the picture it looks like the caliper bracket might actually be rubbing

 

[RossKean]

Are there pads left? That wear is a lot further inboard than the pads should reach. In the picture it looks like the caliper bracket might actually be rubbing

I think the rotor heated up enough to literally burn the paint off - not eroded by physical contact.

 

[Oldjeep]

I think the rotor heated up enough to literally burn the paint off - not eroded by physical contact.

The grooving is what makes me wonder.

 

[RossKean]

The grooving is what makes me wonder.

Hard to say without seeing it in person. Definitely grooving and quite possibly beyond where the pads should contact (not sure). Paint beyond that has been severely compromised due to heat, I believe.

 

[Wingman]

I hit a patch of sandy dirt when coming to a stop on my way to work a couple years ago and the rear brake wouldn’t release afterwards. I had to crack the rear line loose to release pressure so I could ride home. I thought it was a collapsed rubber brake line, but the blockage ended up being inside the abs module.

I had changed the fluid every few years, but didn’t know that I needed to activate the abs pump as part of the flush procedure. Since I rarely activate abs when riding, the fluid within the module was absolutely nasty and there was rust inside. I replaced it with a used abs module because Yamaha is really proud of that particular assembly.

 

[Bounce]

How often do you flush your hydraulics? When I hear "boiling" that's my first concern.

 

[RossKean]

I hit a patch of sandy dirt when coming to a stop on my way to work a couple years ago and the rear brake wouldn’t release afterwards. I had to crack the rear line loose to release pressure so I could ride home. I thought it was a collapsed rubber brake line, but the blockage ended up being inside the abs module.

I had changed the fluid every few years, but didn’t know that I needed to activate the abs pump as part of the flush procedure. Since I rarely activate abs when riding, the fluid within the module was absolutely nasty and there was rust inside. I replaced it with a used abs module because Yamaha is really proud of that particular assembly.

Until my last fluid flush (last year), I had never actuated the ABS while flushing (in almost 300,000 FJR miles) and never had a problem with any of the braking circuits. I do, however, deliberately "exercise" the ABS from time-to-time while riding. Partly to move fluid, partly to ensure that it works as intended and partly to maintain familiarity with the ABS operation - less likely to be taken by surprise when it is activated in an emergency stop or on a surface that provides less traction.

How often do you flush your hydraulics? When I hear "boiling" that's my first concern.

Yeah, me too. Dry DOT4 has a boiling point of 230°C (446°F). Wet DOT4 boils at 155°C (311°F).
446°F is HOT - and that's the fluid temperature! The rotor and caliper (not to mention the pistons and seals) are going to be hotter than that.



I flush mine every two years. I would probably do it annually if I lived in a very humid environment or if I rode a lot in the rain. Cheap and easy maintenance procedure. Even without Speed Bleeders, I can do the three front bleeders, the rear bleeder and the clutch in an hour - including plastic removal to access the rear reservoir. I take a little longer because I also do the critical maintenance on the brake pedal pivot, clutch lever, front brake lever and shifter linkage at the same time. (Those get done every year).

 

[Whooshka]

Are there pads left? That wear is a lot further inboard than the pads should reach. In the picture it looks like the caliper bracket might actually be rubbing

I'm with you on this. Pads and/or caliper is cutting into the "carrier" portion beyond the normal braking surface. That rear rotor and I'd bet the pads are toast.

And to the OP... cleaning the bike IS part of normal maintenance. It helps you give your bike a visual check and stops shit like crud and rust from forming.

 

[Bounce]

Yeah, me too. Dry DOT4 has a boiling point of 230°C (446°F). Wet DOT4 boils at 155°C (311°F).
446°F is HOT - and that's the fluid temperature! The rotor and caliper (not to mention the pistons and seals) are going to be hotter than that.

I flush mine every two years. I would probably do it annually if I lived in a very humid environment or if I rode a lot in the rain. Cheap and easy maintenance procedure. Even without Speed Bleeders, I can do the three front bleeders, the rear bleeder and the clutch in an hour - including plastic removal to access the rear reservoir. I take a little longer because I also do the critical maintenance on the brake pedal pivot, clutch lever, front brake lever and shifter linkage at the same time. (Those get done every year).

Yup. Of more a concern than the boiling point of the DOT3/4/etc is the boiling point of water and that the DOT3/4 is hygroscopic (absorbs moisture from atmo). You're doing everything I was taught to do about it (flush every other year at a minimum). One thing that caught up a friend on a ride to Pikes Peak was that, he overlooked flushing his clutch. Having just come off an HD, he wasn't used to hydraulic clutches and simply overlooked it. At the top, he lost clutch control and didn't get it back until back to about the guard shack. (higher altitude boiling the water at lower temps)

 

[RossKean]

Of more a concern than the boiling point of the DOT3/4/etc is the boiling point of water and that the DOT3/4 is hygroscopic

Water is fully soluble in DOT3/4 and the mixture boiling point drops as the moisture content becomes greater. (Look at the graph I posted.) Very unlikely to boil under any reasonably normal circumstances, but becomes more likely as water percentage increases; especially with a sticking brake. While failure to change fluid soon enough might have contributed to the OP's problem, the root cause was the stuck (or inadvertently applied) rear brake. Given the appearance of that rotor and the burned paint on it, there was a serious issue far beyond wet brake fluid! A problem would have resulted even if the fluid was pristine. Can't imagine not stopping to investigate immediately once I had noticed an apparent lack of power in higher gears.

At the top, he lost clutch control and didn't get it back until back to about the guard shack.

Brake fluid heats up as a function of friction between the pads and the rotor. I wasn't aware that clutch fluid could get hot enough to boil - even when wet.
Contaminated fluid at 5% water still has to get to 150 °C (300°F) before it will boil. Of course, there is reduction in boiling point at increased altitude.
(Just looked it up - pure water boils at 184°F at 15,000 ft, 212°F at sea level. Not sure about a DOT4/water solution. Pikes Peak is 14,115 feet. )

 

[thefix]

FWIW- most riders or dealers never look at the manual. Rear brake pedal often set too high. It's supposed to be significantly below the level of the foot peg. I greased my 1st time just 2 weeks ago at 19k miles. It was dry, I USE WATERPROOF grease. There is a groove to hold the grease. ... Or use PJ1 black chain lube, it doesn't wash out either. A squirt of anything else from a can is looking for failure. Hope you get it resolved w/o dealer.

 

[SilverStreak]

This is 2008 1300AE - no clutch, just shift version. What has me puzzled is that the bike came to a stop at a stop sign, and only after I released the brake lever and applied it again did it fail. Then I tried the rear and that was also failing.

The other symptom is that before this, while riding in 5th at 2000 RPM giving it gas did not seem to increase power. It was as if I had not done anything with the throttle. Kicking it down a gear picked up the RPM and suddenly the bike accelerated nicely, particularly when I dropped it into 3rd. But the RPM had to be around 3000 for it to respond correctly.

Also, the front level was collapsing totally. The rear was collapsing, but if I really pressed all the way hard I had a tiny bit - just barely enough to keep the bike from rolling easily. I thought I had a broken brake line but there was no fluid coming out anywhere. The bike had stopped normally. It was only after I rolled forward a little to see traffic and re-applied the front brake, and then the rear, that I realized I had no brakes at all.

Thanks for the comments above about the front calipers dragging. I have not been riding much so it may be that I forgot to watch foot position on the rear brake and was dragging it. However, I have some play in the back brake just to avoid that issue. It still does not make a lot of sense to me since if the rear break is applying pressure to 2 of the front pads it should not be using the front reservoir. ie. the rear pedal has it's own reservoir and when I bled the brakes 2 years ago it was a separate operation for front and rear. I need to look at the schematics to see how the rear applies the front brakes. I thought it was the front that applied pressure to the rear. Might be getting my bikes confused.

The idea of not having any brakes front or rear is scary. A failure like this should never happen, even if you mess up one brake set by burning the pads/rotor or lose a brake line. I am going to look at things later this weekend and then have the Yamaha shop check the bike and prepare for a $1500+ bill. I expect it is the ABS controller (maybe that got affected by the hot brake fluid?) I will have them do a few other things since the only thing I have done on the bike in 10,000 miles is change the oil every season/3000 miles and changed the coolant and brake fluid 2 years (4000 miles) ago. I am at 30,000+ now. Still, I am now wondering if I want to keep a bike that can have both sets of brakes fail at the same time. That is bad engineering. At this point, my smile as I hit 75 on the highway might be a bit tremulous.

P.S. Probably not relevant: For oil changes I used Mobile 1 10w-40 with Mobile 1 filter this spring and last year. Yamaha oil and then Rotella 5 for diesel once in the past. Mobile 1 gives better clutch feel when I twist the throttle and the automatic clutch starts to grab.

You used "Mobile 1 10w-40" or

Mobil 1 Racing™ 4T 10W-40 ?​

 

[Bounce]

You used "Mobile 1 10w-40" or

Mobil 1 Racing™ 4T 10W-40 ?​

I've used both on my 2003 FJR. From before there was a T to after.

 

[Ishkatan]

You used "Mobile 1 10w-40" or

Mobil 1 Racing™ 4T 10W-40 ?​

"Mobile 1 10w-40". I did not know they had "Racing" oil. Now I am not sure if it said "High Mileage" or just 10W-40.

 

[Ishkatan]

Got voice message from the shop. Basically the problem was what you guys suggested here - I boiled the brake fluid. When I dropped it off, the shop explained that boiling the brake fluid in back can affect the front because they both share the same ABS unit. They are not totally separate since there is one ABS unit. I probably rested my foot on the brake and and was not aware I was doing it.

"Plenty of meat on the brake pads" (I do a lot of engine braking) and they tested everything and it is ready to ride. (I think they replaced the rear rotor and front right rotor - message was not clear - I will be checking but that was the expected repair.)

 

[RossKean]

Thanks for the follow-up. I'm not convinced that the shared ABS unit was responsible for both front and rear to go out, but I suppose it doesn't matter. If, in fact, they also replaced the right front rotor due to damage, it seems likely that the linked piston pair was also overheated (from application of the rear brake). Although the two piston pairs in the right caliper are not hydraulically connected to each other, cooking the lower would also heat the upper by conduction.

If they didn't replace them, keep an eye on brake piston seals and be prepared to change them out if there is any evidence of a leak or if the pads are reluctant to retract when you ease off the brake. I will assume the shop checked them. I also assume they did a full and thorough fluid flush...

 

[Ishkatan]

So I just picked up the bike. The shop did NOT change the rotors, pads or fluid. They opened the master cylinders and said the fluid looked good, no indication that it boiled, no indication of water. There is 4/32 of pad left all around and the rotors are not warped and have plenty or meat on them. While there was some discoloration in spots the color rubbed away when they took it for a test ride. Basically, they did not want to do work they did not think was needed. They also checked the radiator coolant per my request and said it was fine. Can't justify any work.

The ABS unit requires the use of a special tool when doing a brake fluid change. They did not want to change the brake fluid since I did it about 2 years ago but only about 2000-3000 miles ago and the fluid looked so good. (I did not know about the ABS module issue, just kept pumping the brakes and filling before the cylinder ran dry and used the entire can.) They have the special tool but apparently it does not work very well and they had issues with getting air stuck in the ABS unit. "There is a risk of screwing the brake system up every time you change the fluid so if it looks good it's better to leave it until you know for sure it needs it."

The explanation of what might have happened is that the brakes are linked through the ABS unit. The 2nd mechanic speculated that the brake pads may have swelled with heat and the ABS sensor thought that the brakes were being applied too hard so it opened up to release pressure. When I turned off the bike and then turned it on again the ABS valves closed. He suggested that if this happens again I should try turning the bike off for 5 seconds and then turning it on again. Things that make you say "Hmmmm.....".

He also said that this was a bad design. Someone figured all 4 wheels in a car share the ABS unit so what is good for cars is good for bikes. They moved away from this design in later models and in adventure bikes. Adventure bikes have separate ABS units for front and rear and you can turn the ABS off. Well that makes me want a new bike. Can't retrofit.

They said the bike is safe to ride and I should be careful while I test it, and stop riding the rear brake.

Finally, before this event the rear brake had an inch or more of play in it before gripping well. During the event it fell several inches, close to vertical. Now it has just a small amount of play in it. I turn off the bike in Neutral and pushed it into my garage so I know the rear is not gripping when the brake is not depressed.

At this point the bike is parked until next week when I plan to take another close look at the pads and do some of my own testing. None of the explanations make me feel good, but the bike was fun to ride home and worked flawlessly.

 

[BigOgre]

"There is a risk of screwing the brake system up every time you change the fluid so if it looks good it's better to leave it until you know for sure it needs it."

Your bike, your comfort zone, but I'd find a new shop.