rear brake keeps fading

[moondog]

The rear brake on my 2005 FJR1300ABS, 25,000 miles, keeps fading. Had the brake fluid flushed and changed by 2 different shops. Had the brake fluid flushed and changed last May in Linclon, Neb. on a trip. Now in August brake has completely faded again, no stopping power at all. One mechanic is absolutly certain it's the master cylinder gone bad. Another mechanic is certain its NOT the master cylinder. So at this point I have new hoses on order since the owner's manual says to replace these every four years. I might as well replace these before I have a new master cylinder put in or fixed. Correct me if I'm wrong but if it IS the master cylinder gone bad then the brake wouldn't work no matter what I do, replace the brake fluid or not. (Pads are still fresh, replaced just last year but I will have the mechanic check these anyway.) Anyone with a similar problem?

 

[Fred W]

moondog,

Tell us a little more about what happens when it "fades".

Can you ever brake hard enough to actuate the ABS?

Is this only happening when the bike has been ridden for a while, or will it fade when cold?

When it fades, does it feel like the pedal is depressing too easily / too far?

Or does the pedal feel normal but you aren't getting the stopping power that you expect?

 

[Donal]

I guess my question is why are you using the rear brake to the point where it fades?

IMHO the rear brake is really only useful in slow traffic conditions. If you need consistent stopping power use the front brake only. Isn't that why Yamaha installed two larger rotors and more pistons on the front?

Don

 

[mcatrophy]

The rear brake on my 2005 FJR1300ABS, 25,000 miles, keeps fading. ...

Have you checked the brake lever isn't binding? The pivot can seize if not lubricated occasionally.

 

[moondog]

I guess my question is why are you using the rear brake to the point where it fades?

IMHO the rear brake is really only useful in slow traffic conditions. If you need consistent stopping power use the front brake only. Isn't that why Yamaha installed two larger rotors and more pistons on the front?

Don

From YAMAHA booklet LIT-11626-15-41"YOU AND YOUR MOTORCCYLE:RIDING TIPS" page 17 "Always apply both the front and the rear brakes at the same time." which is what I have been doing for the past 5 years on this bike. I always apply both brakes at the same time with approx same force.

 

[Ignacio]

From YAMAHA booklet LIT-11626-15-41"YOU AND YOUR MOTORCCYLE:RIDING TIPS" page 17 "Always apply both the front and the rear brakes at the same time." which is what I have been doing for the past 5 years on this bike. I always apply both brakes at the same time with approx same force.

There you go...you appear to be reading something into the booklet that's not there....not that I'd necessarily treat the booklet as total gospel. Regardless, nowhere does it say to apply the same force.Try more front brake.

I've cooked my rear brake once and it was a case of a lot of downhill twisties that I was tired and favoring the rear.

 

[moondog]

moondog,

Tell us a little more about what happens when it "fades".

Can you ever brake hard enough to actuate the ABS?

Is this only happening when the bike has been ridden for a while, or will it fade when cold?

When it fades, does it feel like the pedal is depressing too easily / too far?

Or does the pedal feel normal but you aren't getting the stopping power that you expect?

When I have the bike up on the center stand and in neutral and press the rear brake lever all the way down, yes then I cannot turn the rear wheel at all by hand. But when riding and I press the brake lever all the way down, nothing, no stopping power whatsoever right off the bat.

 

[moondog]

From YAMAHA booklet LIT-11626-15-41"YOU AND YOUR MOTORCCYLE:RIDING TIPS" page 17 "Always apply both the front and the rear brakes at the same time." which is what I have been doing for the past 5 years on this bike. I always apply both brakes at the same time with approx same force.

There you go...you appear to be reading something into the booklet that's not there....not that I'd necessarily treat the booklet as total gospel. Regardless, nowhere does it say to apply the same force. Try more front brake.

I've cooked my rear brake once and it was a case of a lot of downhill twisties that I was tired and favoring the rear.

Nowhere does it say NOT to apply same force either. I guess you and I have different riding styles.

 

[Ignacio]

Nowhere does it say NOT to apply same force either. I guess you and I have different riding styles.

You're totally right! I guess with your riding style you'll have to make some choices about putting half your stopping force in one rear 282mm rotor or or more of it in two 320mm rotors. Good luck in finding a solution.

 

[Fred W]

moondog,

Tell us a little more about what happens when it "fades".

Can you ever brake hard enough to actuate the ABS?

Is this only happening when the bike has been ridden for a while, or will it fade when cold?

When it fades, does it feel like the pedal is depressing too easily / too far?

Or does the pedal feel normal but you aren't getting the stopping power that you expect?

When I have the bike up on the center stand and in neutral and press the rear brake lever all the way down, yes then I cannot turn the rear wheel at all by hand. But when riding and I press the brake lever all the way down, nothing, no stopping power whatsoever right off the bat.

OK, there is something wrong with that. On a 2005 (first gen) w/o ABS you should be able to stomp on the rear brake pedal and lock up the brake. Since yours does have ABS (as does mine) you should be able to stomp the rear pedal and feel the brake pedal pulsate, indicating that the ABS is cycling to prevent tire lock up.

You are getting some action since the pedal will make it so the wheel won't turn by hand, but not enough hydraulic pressure is being delivered.

You didn't say if the pedal feels like it is traveling too far, and that is an important detail. If it is, then I suspect that you have air trapped in the system somewhere.

If the pedal feels normal and firm, then I suspect that something in the system is blocking the fluid flow. Remember that we have the added complexity of the ABS pump and control valves in our systems.

 

[wheatonFJR]

Always apply more front brake than rear. During braking action, the bikes weight loads up the front wheel, while the rear wheel unloads some weight.

That's why double disks on front, single on the rear. Rear braking is good for fine adjusting...but bulk of braking load should be through the front brakes.

Check out various riding technique books...

Still, it sounds like something is funky with your rear brake...obviously.

 

[ionbeam]

Supplementing what Fred said --

This is a rare but not unheard of problem situation. It has been cured by replacing the master cylinder and by bleeding the brake caliper.

Does bleeding the brake system allow your brake system to work normally and ABS to function normally for days or weeks at a time?

Bad brake lines usually affect fluid return to the MC causing the brakes to drag or brake fluid leaks.

There have been a couple of bikes that have recently been fixed by replacing the master cylinder. This also will entail some brake bleeding which may be the actual fix and not the master cylinder replacement. The MC replacement may disturb air in the lines and move the bubble(s) to a point where bleeding will take it out.

If bleeding your brakes at least temporarily fixes the problem then what you actually need to troubleshoot is how air keeps getting into your brake system. It could be as simple as leaks around or through the bleed screw itself. I assume you have seen no signs of brake fluid leaks? Including the ABS metering block? It is fairly simple to test the ABS system, do you know that your rear ABS is working correctly?

Edit to ask: You don't have speed bleeders do you? In my car club we have found speed bleeders to fail quite frequently. Motorcycle speed bleeders seem to last longer but they do fail.

 

[Donal]

There was a similar thread recently. If I remember correctly the solution then was to elevate the rear calliper (slave cylinder) above the master cylinder and then carry out the bleed procedure which resulted in several large air bubbles coming out.

Don

 

[wfooshee]

You say fading, but you don't say hot. Is the brake actually heating up before this non-action? If not, then it's not fade, it's something else.

If it is overheating leading to fade, then the pedal sticking is a known issue. The pivot gets grungy, and the pedal doesn't lift on its spring, leaving the brake dragging. Not enough to affect riding, but enough to cook the rotor and hat the caliper to boiling.

If there's no braking action from a stone-cold start, then I for one am in over my head. I will say, though, that stopping the wheel while the bike is on the centerstand is not the same thing as actually slowing down the bike. A system that needs bleeding will stop the wheel on the centerstand just fine.

 

[Constant Mesh]

"When I have the bike up on the center stand and in neutral and press the rear brake lever all the way down, yes then I cannot turn the rear wheel at all by hand."

Your phrase "all the way down" tells us there are gas bubbles in the system. You might do the same test but this time turn on the ignition so that the ABS components are energized. Something wacky may be going on inside the ABS unit -- the solenoid valve may be opening when it shouldn't, etc.

Before replacing/refurbishing the master cylinder I would reconnect the hoses so that the caliper hose goes directly to the master cylinder -- get the ABS out of the loop.

If the master cylinder is misbehaving it can probably be refurbished with a new internals kit ($31) from Yamaha. A new master cylinder will cost at least $73.

 

[moondog]

moondog,

Tell us a little more about what happens when it "fades".

Can you ever brake hard enough to actuate the ABS?

Is this only happening when the bike has been ridden for a while, or will it fade when cold?

When it fades, does it feel like the pedal is depressing too easily / too far?

Or does the pedal feel normal but you aren't getting the stopping power that you expect?

When I have the bike up on the center stand and in neutral and press the rear brake lever all the way down, yes then I cannot turn the rear wheel at all by hand. But when riding and I press the brake lever all the way down, nothing, no stopping power whatsoever right off the bat.

OK, there is something wrong with that. On a 2005 (first gen) w/o ABS you should be able to stomp on the rear brake pedal and lock up the brake. Since yours does have ABS (as does mine) you should be able to stomp the rear pedal and feel the brake pedal pulsate, indicating that the ABS is cycling to prevent tire lock up.

You are getting some action since the pedal will make it so the wheel won't turn by hand, but not enough hydraulic pressure is being delivered.

You didn't say if the pedal feels like it is traveling too far, and that is an important detail. If it is, then I suspect that you have air trapped in the system somewhere.

If the pedal feels normal and firm, then I suspect that something in the system is blocking the fluid flow. Remember that we have the added complexity of the ABS pump and control valves in our systems.

Yes sir, you sound like you know what you are talking about. But what every one here is ignoring is what the owner's manual says: "Replace the brake hoses every four years." And in my case I'm 2 years over due. They are on order.

 

[Fred W]

Yes, ignoring that mostly because that isn't very likely to be what is causing your problem.

However, in the course of replacing those hoses you very well may fix it, because you'll be fully bleeding the entire system.

Replacing brake hoses every two years is just not required. If it were my bike and my money I'd be bleeding the brakes first.

 

[SkooterG]

Yes sir, you sound like you know what you are talking about. But what every one here is ignoring is what the owner's manual says: "Replace the brake hoses every four years." And in my case I'm 2 years over due. They are on order.

Well, I guess that will make you the single smartest feller on this forum. Cause in the 6+ years I have been here, you are the first I have heard replacing their brake lines because 'the manual said so'.

So what does that say about the hundreds of us 7, 8, and 9 year old FJR owners with original brake lines and no brake issues?

You started this thread seeking help. You are getting a lot of good advice from folks with a lot of knowledge. Not sure why you are choosing to ignore it.

Best of luck to you.

And just for general fyi - are you replacing ALL the brake lines? How many are there for a Gen I abs FJR? How much did that cost? Oh, and replacing with OEM? Or aftermarket?

 

[RadioHowie]

....and replacing the "hard" lines along with the "soft" ones???