07 Brakes have a mind of their own

[wfooshee]

Just to reiterate, the ABS system CANNOT apply the brakes. All it can do is release them. When it senses a wheel lockup, it interrupts the brake pressure already being applied, and then removes its interruption. ABS has no method of applying brake pressure.

 

[HuskyRider]

ABS can apply the brakes without lever pressure, that’s why you hear a motor running during abs stops. Sounds like you have a new option like traction control!

 

[SkooterG]

ABS can apply the brakes without lever pressure, that’s why you hear a motor running during abs stops. Sounds like you have a new option like traction control!

Huh?

Care to elaborate with specific details?

Your statement goes against everything I understand about the FJR's ABS brake system. There's no 'motor'. Just a 'pump' that *releases* pressure momentarily, and let's it build back up again before repeating the cycle.

 

[Scout]

ABS can apply the brakes without lever pressure, that’s why you hear a motor running during abs stops. Sounds like you have a new option like traction control!

The way I read the FJR shop manual (pages 1-18 and 1-19), HuskyRider is correct. When the ABS is activated, a pump recirculates brake fluid in a loop as the pressure is reduced to the calipers. As the brake reapplies (pulses), a solenoid valve alternately lets this pressure go to the caliper or be recirculated. If that pump activates when there is no peddle pressure from rider inputs, it will be just like pulling the brake handle or foot pedal. The bike is gonna stop!

This condition is scares the daylights out of me! Go get your ABS system fixed! It's supposed to throw error codes when something goes wrong, but I don't know if this sort of failure will be detected... It may be the system detects a wheel lockup due to bad wheel sensors and the pump activates. Donno...

 

[SkooterG]

ABS can apply the brakes without lever pressure, that’s why you hear a motor running during abs stops. Sounds like you have a new option like traction control!

The way I read the FJR shop manual (pages 1-18 and 1-19), HuskyRider is correct. When the ABS is activated, a pump recirculates brake fluid in a loop as the pressure is reduced to the calipers. As the brake reapplies (pulses), a solenoid valve alternately lets this pressure go to the caliper or be recirculated. If that pump activates when there is no peddle pressure from rider inputs, it will be just like pulling the brake handle or foot pedal. The bike is gonna stop!

This condition is scares the daylights out of me! Go get your ABS system fixed! It's supposed to throw error codes when something goes wrong, but I don't know if this sort of failure will be detected... It may be the system detects a wheel lockup due to bad wheel sensors and the pump activates. Donno...

Very interesting. I will do some more research on this. I still find it hard to believe the pump can activate brakes on it's own.

 

[charismaticmegafauna]

Not to make light of the issue -- but, it reminds me of a story I heard:

Once, a rider bought a new bike that had drum brakes (it was a long time ago) and early-on something happened that locked-up the front brake and slid the front wheel. Luckily he wasn't going fast and was in a position to save the incident. He disassembled the front brake and found a loose and mangled brake shoe return spring -- apparently, the spring broke/came loose and lodged between the brake shoe and drum - locking the brake/wheel.

The rider took the offending spring to the dealer a put it on the counter-top and told the story -- with feeling!

The dealer said: "I've never heard of that happening before."

The rider said, "Of course not -- they're all dead."

 

[wfooshee]

ABS can apply the brakes without lever pressure, that’s why you hear a motor running during abs stops. Sounds like you have a new option like traction control!

The way I read the FJR shop manual (pages 1-18 and 1-19), HuskyRider is correct. When the ABS is activated, a pump recirculates brake fluid in a loop as the pressure is reduced to the calipers. As the brake reapplies (pulses), a solenoid valve alternately lets this pressure go to the caliper or be recirculated. If that pump activates when there is no peddle pressure from rider inputs, it will be just like pulling the brake handle or foot pedal. The bike is gonna stop!

This condition is scares the daylights out of me! Go get your ABS system fixed! It's supposed to throw error codes when something goes wrong, but I don't know if this sort of failure will be detected... It may be the system detects a wheel lockup due to bad wheel sensors and the pump activates. Donno...

The phrase "As the brake reapplies" means the interruption of brake pressure is removed, not that additional pressure is added.

The ABS "motor" keeps pressure in its actuators, not the actual brake system. The actuators in the ABS system are solenoids which open to relieve pressure in the brake line momentarily while preventing further fluid flow, thus releasing brakes at the caliper. The solenoid then resets, allowing hydraulic pressure to return to the brake line, and the system continues monitoring wheel speed for impending lockup. The solenoid can be cycled quite rapdily, and the hydraulic system for the actuators is completely separate from the hydraulic system for the actual brake lines, and maintains its own pressure system activated by the motor you hear running as the ABS is activated. The motor DOES NOT APPLY BRAKES, it applies pressure to the ABS actuators.

The lever and the pedal are the only sources of brake pressure, unless something like a stuck caliper heats up the system by dragging the pads, and the resulting heat applies pressure through some means like boiling water out of the brake fluid. The ONLY thing ABS can do to the brakes is release them by interrupting line pressure.

Bleed the brakes.

 

[Scout]

Well, lets think about it. The ABS system has to release pressure from the brakes to prevent a lockup, right? Then it's got to reapply that pressure to continue the stop. Where does the pressure come from each time it reapplies the brakes? Based on the diagram in the FJR manual, it comes from that electric pump. If the only pressure in the system was from your brake lever, the ABS would quickly bleed that pressure off releasing brake pressure each time it pulses. Your lever would quickly hit the handlebar if that was the case. The pump is a source of pressure in the system. And if some malfunction causes that pump to start unexpectedly, it will independently create pressure in the system.

By the way, I stopped by the Yamaha dealer today and asked a mechanic about this problem. He had never heard of it happening, but he did agree that if that ABS motor started, it would indeed create pressure in the system. He thought the problem might be a bad sensor.

 

[wfooshee]

Well, lets think about it. The ABS system has to release pressure from the brakes to prevent a lockup, right? Then it's got to reapply that pressure to continue the stop. Where does the pressure come from each time it reapplies the brakes? Based on the diagram in the FJR manual, it comes from that electric pump. If the only pressure in the system was from your brake lever, the ABS would quickly bleed that pressure off releasing brake pressure each time it pulses. Your lever would quickly hit the handlebar if that was the case. The pump is a source of pressure in the system. And if some malfunction causes that pump to start unexpectedly, it will independently create pressure in the system.
By the way, I stopped by the Yamaha dealer today and asked a mechanic about this problem. He had never heard of it happening, but he did agree that if that ABS motor started, it would indeed create pressure in the system. He thought the problem might be a bad sensor.

I will admit that I do not have specifics of the FJR anti-lock system, but every automotive system I have seen works like this:

At impending lock-up, the system energizes a solenoid that blocks the brake line to the affected wheel. That's it. No pressure relief, but no increase, either. Just a block. If the wheel is still decelerating too rapidly, another solenoid opens to bleed pressure between the first solenoid and the caliper. (This might be done with a second stage on the same solenoid.) Fluid released is collected in the accumulator. When wheel speed is correct the collected fluid is returned to the line and the solenoids are de-energized. That's where the pressure comes from: the fluid collected in the first place. As far as I know there's no additional fluid available for additional pressure. The ABS accumulator does not have access to the master cylinder's reservoir. This happens astonishingly fast, and the interruption of the hydraulic circuit will feed back into the brake line and results in the pulsation most of you feel at the lever or pedal. Some systems try to isolate that pulsation but it is difficult to do so. Also note that with the solenoids de-energized, the ABS accumulator is completely isolated from the braking system.

Now, I might be wrong, and it wouldn't be the first time this week. It would be the first time today, though! But with everything I've learned about ABS, I see no way for the ABS system to apply brake pressure by itself, out of the blue. I've never seen a documented incident of ABS applying unwanted brake pressure.

 

[SCRider]

The pump is a source of pressure in the system. And if some malfunction causes that pump to start unexpectedly, it will independently create pressure in the system.

+1 Scout. I studied the manual as well and came to the same conclusion. The only thing that bothered me is that the pump would return the released fluid from the ABS system back to the reservoir in the front brake master cylinder if the handle were not pulled to close off the port from the reservoir. He did state that the front brake lever had slack in it so if his master cylinder were sticking and not returning to fully open, the pump would indeed pressurize the brake system. It seems like he is having 2 failure modes happen at once which is probably why this only happens occasionally. Does this make sense?

SCRider

 

[MartyA]

Great discussion!

He did state that the front brake lever had slack in it so if his master cylinder were sticking and not returning to fully open...

Yes, the third time I did notice that. I actually moved it with one of my fingers just before the bike came to a stop. It clicked out the moment the bike stopped rolling. I cannot reliably state that it also was the case the first two times.

My appointment is Tues AM for the 24,000 mile service. I can't wait to talk to the mechanic about it. They think I'm half nuts anyway since I was just in 2 weeks ago for the 20,000 mile service. I did mention something was going on with the brakes at one of the recent maintenance visits but they said they didn't find anything. My guess is they forgot to check. I am sure they don't have the equipment to test or service the ABS, but I will make them write down to check it and I have to wait and give them a chance before I call Yamaha. Anyone got a phone # for me?

 

[3dogs]

Dude, Sorry about your problem but after reading all the posts on this thread I think you're full of shit. Below are quotes from your previous posts. You state that you bought the bike in April 07 (15 months ago) and you also state that you are going in for a 24,000 mile service. Yet you also mention that you have had 4 FRONT TIRES and 8 REAR TIRES since last spring---In 24,000 miles????

If one does the math you are using up rear tires at a rate of 3000 miles for each and a front tire every 6000 miles. I think you should fix the excessive tire wear problem before the brakes. At any rate something doesn't add up here. Your brake story is ridiculous and the amount of tires you're going through is stupid???? Other than those issues hope you get your brakes fixed. In the mean time just keep riding--maybe the throttle will start accelerating the bike all by it self then you will only have to hold on and steer!

"Appreciate all the responses. I bought the bike new April 07. I have had 4 front tires and 8 rear tires since new last spring, all but one done by me and my buddy in his garage, so I have had lots of opportunity to mess that ABS up. The last occurrence of this brake lockup was last week at about the 3,000 mile point of a 4,000 mile New England / Canada trip."

"My appointment is Tues AM for the 24,000 mile service. I can't wait to talk to the mechanic about it. They think I'm half nuts anyway since I was just in 2 weeks ago for the 20,000 mile service. I did mention something was going on with the brakes at one of the recent maintenance visits but they said they didn't find anything. My guess is they forgot to check. I am sure they don't have the equipment to test or service the ABS, but I will make them write down to check it and I have to wait and give them a chance before I call Yamaha. Anyone got a phone # for me?"

 

[slapnpop]

If one does the math you are using up rear tires at a rate of 3000 miles for each and a front tire every 6000 miles. I think you should fix the excessive tire wear problem before the brakes. At any rate something doesn't add up here. Your brake story is ridiculous and the amount of tires you're going through is stupid????

Whether or not this brake problem is real, WTF?!? Take a big 'ole chill pill and back the **** up!

I've worn through about 6 rears and 3 fronts at the above mileage. It's called RIDING THE BIKE! Some people obviously ride a little harder than others. (and as a result end up changing tires in their own garage) I certainly know I'm not alone in this mileage range for people who ride in the mountains, and ride hard.

Pull your head out of your ass and quit jumping someone else's case.

 

[madmike2]

If one does the math you are using up rear tires at a rate of 3000 miles for each and a front tire every 6000 miles. I think you should fix the excessive tire wear problem before the brakes. At any rate something doesn't add up here. Your brake story is ridiculous and the amount of tires you're going through is stupid????

Whether or not this brake problem is real, WTF?!? Take a big 'ole chill pill and back the **** up!

I've worn through about 6 rears and 3 fronts at the above mileage. It's called RIDING THE BIKE! Some people obviously ride a little harder than others. (and as a result end up changing tires in their own garage) I certainly know I'm not alone in this mileage range for people who ride in the mountains, and ride hard.

Pull your head out of your ass and quit jumping someone else's case.

Amen, Brother Travis!!!

And you are not the only guys here who are having that issue because of mountainous roadways or the coarseness of the asphalt.

 

[MartyA]

3dogs you really need to find another hobby.

Not sure why I am clarifying this for you but you said I was full of sh*t and stupid and I would like to point out that you don't even know me. For your information, my bike is rarely in the driveway, and is not very shiny. I bought my FJR to ride.

Now, read this slowly and carefully, and if you have any questions don't jump to any more conclusion, ask.

I have posted many times I get around 3,500-4,500 per rear tire. In my post that you quoted but didn't read I merely stated 8 rear tires and 4 fronts, I did NOT state I wore them out. The statement from a post above was

"...check the ABS sensors and make sure that the ABS "hub" that mounts over the axle is properly lined up..."

I pointed out that I had 4 fronts and 8 rear tires on which meant I had that many opportunities to mess up the position of the ABS "hub" when [SIZE=14pt]changing tires[/SIZE]. In fact, if it is really important to you, I have completely worn out 4 rear tires, have 2 partially worn ones on the porch, 1 with about 2,000 miles is in a VA dealer's dumpster with a big honking hole in it, and have the [SIZE=36pt]8th[/SIZE] rear tire on the bike now with 4,000 miles on it.

If I have a long trip coming up and I cannot get the required mileage from the tire that is mounted and it has sufficient tread left I remove that tire and put a new on on, saving the partially used tire for later. This I have done twice.

I would tell you about the weekend I completely wore out a brand new rear tire after 765 miles cruising around north Georgia, Tennessee, and North Carolina but that would be well beyond your scope of comprehension so it would be of course just another prevarication on my part, wouldn't it.

Thanks for stepping in guys!! As you can see I tend to be very patient with the feeble....

On topic, no brake report from the dealer yet.

 

[huron52]

Ok, personally I have rode with or at least near Marty and I can say that YES he can wear out a set of tires that fast or short of time.

I am also from the school that if I am going on a long trip, put a new set on. I have taken the used set off put them on the shelf and when I get back put them back on. Excellent piece of mind.

In fact today I am getting my used pilot Road 2's off and putting a brand new set of Road smarts for the NAFO trip.

Hope they figure it out Marty.....

 

[FJR1300Mark]

I think you said you were headed to the dealer and that you were going to bleed the brakes.

I am interested in what you and or the dealer finds and how you fix it.

the discussion on ABS and the pump has me wanting to read the shop manual myself too.

Hope it is as easy as the fluid or abs unit, if it's covered under warantee.

thanks for the update.

 

[MartyA]

Just talked to the mechanic at the dealer. He reports that he talked to a Yamaha engineer who indicated that if there was an electrical fault with the ABS system it would just not function, and the brakes would be regular brakes, until the ABS system sensed no fault condition again. He thought a dashboard light would come on also. Is there an ABS failure light on the dashboard?

He suggested the fluids should be flushed and replaced. Either the fluids were heating up or the fluids were dirty and a small bit was perhaps catching one of the pistons and holding the pad against the rotor creating heat. The pads and rotors are the originals and they look fine, not worn much at all, and not burnt. Brake fluid is hydroscopic so maybe there was a little moisture in the fluid? Since I purchased the bike the master cylinder was not opened until this week. The dealer even called the engineer back as they flushed the lines to be sure they were covering all the lines with the correct procedure.

Can someone check the shop manual and tell me if there is either an idiot light on the dash or a fault code to read if the ABS does show a fault? As I mentioned earlier this dealer is a small town low volume dealer, and while I do not question their efforts or sincerity I do question their ability much beyond the standard stuff like oil changes, carbie balance, head gaskets, and tire rotation...

I just wonder if there is a certain combination of things that happen to cause this, or if it is indeed as simple as bad brake fluid.

I can pick up the bike on Monday. If it happens again I'll try to pay more attention to what is going on.

I did ask the Sales guy to quote me a 2009 with trade after he tells me what the color is.

 

[CCook82]

Ditto on the tire wear. I averaged 3500 miles on the rear with the Avon Azaros. I live in the Smokey mountains and ride two up quite a bit. Use 42 pounds in the rear. Front wear is not quite twice as long.

This spring I mounted the first Avon Storms. Yeah, I know, I know. Went to Texas hill country. I was loaded with wifey and tools, etc to go into Mexico. I wore the tire to one half tread depth in 800 miles on the chip sealed roads in the hill country. Was with others and the pace was brisk. I did not go into Mexico for fear I would not get another tire, even if I crossed the border with a fresh one.

With this, I gave up, and upon turning home, I mounted the Metzeler ME880 on the rear. I guess I should get a Goldwing or BMW LT, but I would like to stay with the FJR. The Metzeler seems to be the answer for now, but I have toned it down fearing what the consequences might be.

 

[FJRJOE]

Make sure the brake reservoir is not overfilled.If the fluid expands when hot it can apply the brakes.

Friend of mine had a problem with his BMW clutch slipping when hot.The clutch fluid was over filled<when it got

hot it would start to apply the clutch.