Front Brake Issue

[vettrick]

I'm still fighting a front brake issue. Last fall I was on a ride and my front brake lever suddenly went to the handlebar with no braking effect. That was scary!
Over the winter I rebuilt the calipers, new pads, and put a new piston with seals in the master cylinder. Didn't touch the lines. Also added speed bleeders.
I bled the lines a couple of times to make sure the air is out. I had a good hard feel.
That is until I move the bike. Now if I even roll it three feet the brake lever drops to the bar again...no breaks at all. I can pump it up with three strokes and it feels good. Roll the bike and nothing. There are no leaks...dry everywhere.
I am at a loss on this one. It isn't that complicated of a system. But I'm about to break down and take it to the dealer. In total, I have used about 3/4 quart in the bleeding processes.
Any ideas what might cause this?

 

[dabobmeister]

I had something similar after I rebuilt my calipers. I had used non-yamaha pistons and they were very very slightly out of spec, and the brake fluid could push past the first seal.

If you take off the outer seal and there is any brake fluid there you could have something similar.

Rebuilt with expensive oem pistons and no problems since.

Hope you get it sorted.

 

[FinalImpact]

With a block of wood under the headers, hold the end of pen up to the rotor (on the fork leg) and spin it. Each rotor should maintain the same contact distance and sound from the object used.

So with the nose off the ground, pads seated and spin the wheel - what do you hear? I would expect the initial rotation to be a brushing sound with 100% contact. I admit this is abstract; but what you describe sounds like the rotors are bent and pushing the pads & pistons away so you have to pump the lever to seat the pistons and build pressure.

When is the last time they worked proper? Is there ANY WAY the rotor on one or both sides could be bent?

^ ^ ^ ^ ^
That is the only thing that changes when rolled verses just being a timing thing.

That said, caliper seals are NOT bi-directional. They only go in one way. Piston cups only go in one way. As you mentioned if either of these were blowing past, you will have noticeable fluid out of the bike.

This is very unusual if a bent rotor is not to blame. So there is no chance its just random? Do you have aftermarket levers? Users have reported the lever height adjusting cam has MOVED UNDER PRESSURE allowing the lever to bottom on the bar. Is that possible?

My last card to play is the piston in the master cylinder is NOT RETURNING. Even that is hard to say its the cause as the brakes should be stuck on. Are they?
>> Closing comment; if the piston in the MC does not COME OUT ALL THE WAY, it DOES NOT ALLOW the port from the reservoir to open and FILL the PISTON BORE! This will allow it to go down to the bar with no pressure. Make certain the piston is coming out. That's all I have....

 

[Motogiro]

I agree with FI on the master cylinder as suspect from how you've explained it.

Sounds like the master cylinder has total blow by because of an open seal or the piston is stuck and not returning. This is one reason I don't believe in pushing the piston back in the caliper without opening the bleeder valve. Opening the bleeder valve helps prevent old dirty fluid in the line from being pushed back to the master cylinder reservoir which can allow debris to contaminate the master cylinder piston. On many or all ABS brake systems it can cause other problems as well so it's a good practice to get into.

 

[TownsendsFJR1300]

Probably not important but, not asked or posted, were ALL the parts replaced, OEM Yamaha or some knock offs from ???

I have to agree with FI's suspicion re the disc.

If the disc is warped, wheel assembly not re-assembled correctly, etc, once you rotate the wheel, its literally pushing the pads / pistons back INTO THE CALIPER.

Now, your literally pumping the pistons / pads BACK OUT (until they harden again). Once hard, their fine. Move the bike (rotate the ft wheel), it pushes the pistons/pads back in the caliper, thus you have to re-pump...

**If if have a centerstand, put the bike on it and raise the front wheel (sizzor jack or ? under the header). Pump the lever hard and examine the pads which should be right up against the disc's with some drag. Now, slowly spin the wheel some and see if the pads are pushed back in and the drag is diminished or gone... The drag should be consistant ALL THE TIME, however I strongly suspect it'll change and the pads push back in the caliper...

Question, the year bike, did you have the front wheel off for any reason (when all this started)? I ask in that if the forks are not aligned straight, one fork may be pushing a caliper over causing the "retraction"..

 

[vettrick]

Probably not important but, not asked or posted, were ALL the parts replaced, OEM Yamaha or some knock offs from ???

I have to agree with FI's suspicion re the disc.

If the disc is warped, wheel assembly not re-assembled correctly, etc, once you rotate the wheel, its literally pushing the pads / pistons back INTO THE CALIPER.

Now, your literally pumping the pistons / pads BACK OUT (until they harden again). Once hard, their fine. Move the bike (rotate the ft wheel), it pushes the pistons/pads back in the caliper, thus you have to re-pump...

**If if have a centerstand, put the bike on it and raise the front wheel (sizzor jack or ? under the header). Pump the lever hard and examine the pads which should be right up against the disc's with some drag. Now, slowly spin the wheel some and see if the pads are pushed back in and the drag is diminished or gone... The drag should be consistant ALL THE TIME, however I strongly suspect it'll change and the pads push back in the caliper...

Question, the year bike, did you have the front wheel off for any reason (when all this started)? I ask in that if the forks are not aligned straight, one fork may be pushing a caliper over causing the "retraction"..

I think you and FI nailed it with warped rotors. I lifted the front tire off the ground this evening and rotated it. Both sides appear to be off by at least 1/8 inch if not more. There is mucho drag on the high spots. After rotating by hand, I get no brake action at the lever but can pump it up in three squeezes.
So...can the disks be trued/centered or is it time for new parts?
Thanks much guys.

 

[FinalImpact]

I think you and FI nailed it with warped rotors. I lifted the front tire off the ground this evening and rotated it. Both sides appear to be off by at least 1/8 inch if not more. There is mucho drag on the high spots. After rotating by hand, I get no brake action at the lever but can pump it up in three squeezes.
So...can the disks be trued/centered or is it time for new parts?
Thanks much guys.

Replacement is the only option, Has the bike been down or left somewhere that damage could go unreported?

06 and up:
5VX-2581T-01-00 DISC BRAKE ASSY

05 and down:
5VX-2581T-00-00 DISC BRAKE ASSY

Although it may be the same part physically as a tiny detail like heat treating or painting the edge black could roll the Rev but still fit and work.

Be sure to grab new bolts too. Some have had issues and damaged them getting them off.
PN: 90109-064G6-00 BOLT

 

[yamihoe]

+1 totally sounds like the master cylinder.

$.02 officially thrown in! :thumbup:

 

[TownsendsFJR1300]

+1 totally sounds like the master cylinder.

$.02 officially thrown in! :thumbup:

A little late now!!! :spank:

 

[TownsendsFJR1300]

I think you and FI nailed it with warped rotors. I lifted the front tire off the ground this evening and rotated it. Both sides appear to be off by at least 1/8 inch if not more. There is mucho drag on the high spots. After rotating by hand, I get no brake action at the lever but can pump it up in three squeezes.
So...can the disks be trued/centered or is it time for new parts?
Thanks much guys.

Total runout (back and forth sideways) is .10mm or .0039", so yes, your a bit over that..


Just curious, were the brakes draggng badly before (why you rebuilt them)? If they were dragging bad, that would overheat and warp them, especially if they got splashed (rain) while super hot.. And what year is you bike (2 or 4 pistons per pot)?

 

[FinalImpact]

I don't see rain or puddles as a gating factor for taco type deflection. Seems more like impact damage IME.

If it were blazing hot and one half of it quenched rapidly it may change its temper but very unlikely it would be the cause of 1/8" deflection. OK ->> Taco may have been excessive in that description....

 

[vettrick]

This is a 2009 with only 7,350 miles. I'm the second owner but it has never been down. Never been ridden real hard. Very little if any rain. I rebuilt the calipers thinking that was the problem. It wasn't. The bike is used as a weekend special mostly. Do you think it's possible that the disks aren't floating sideways properly from lack of use?
I pulled the wheel off tonight but didn't have time to check it out.
I started pricing new disks and they are expensive!

 

[FinalImpact]

This is a 2009 with only 7,350 miles. I'm the second owner but it has never been down. Never been ridden real hard. Very little if any rain. I rebuilt the calipers thinking that was the problem. It wasn't. The bike is used as a weekend special mostly. Do you think it's possible that the disks aren't floating sideways properly from lack of use?
I pulled the wheel off tonight but didn't have time to check it out.
I started pricing new disks and they are expensive!

Not likely. These are not full floating discs so they move little if at all side to side. They do expand and contract on the hub.

Are both of them bent? It only takes one to be an issue. This is much easier to check on the bike. Do you see any signs of contact from an odd angle that something might have struck it while parked?

Sorry man.

 

[TownsendsFJR1300]

Did you remove the front wheel at all or the rotors recently? Tires changed at a shop (did they drop the wheel and bend the rotors??)

Is the wheel itself tracking true (no crashes)?

ANY BLUING on the disc's?

With what you've mentioned, it sounds as if the axle could be bent, wheel bearings (not likely with the mileage) but your being so far out of spec's on the rotors indicates something not assembled correctly.

IMO, I would re-set the axle, pull and check the axle (to rule that out-probably not the issue). Basically just check and re-set everything from the triples down.

Please check your shop manual re the EXACT PROCEDURE, (ie, loosen the rt lower leg pinch bolt, torque axle to specs, make sure the right fork leg "finds its own happy spot"- do NOT push in or pull out, etc)...

 

[trepetti]

Did you remove the front wheel at all or the rotors recently? Tires changed at a shop (did they drop the wheel and bend the rotors??)

Is the wheel itself tracking true (no crashes)?

ANY BLUING on the disc's?

With what you've mentioned, it sounds as if the axle could be bent, wheel bearings (not likely with the mileage) but your being so far out of spec's on the rotors indicates something not assembled correctly.

IMO, I would re-set the axle, pull and check the axle (to rule that out-probably not the issue). Basically just check and re-set everything from the triples down.

Please check your shop manual re the EXACT PROCEDURE, (ie, loosen the rt lower leg pinch bolt, torque axle to specs, make sure the right fork leg "finds its own happy spot"- do NOT push in or pull out, etc)...

*** Sorry for the Thread-jack ***

Scott, I am about to replace the fork oil in prep for spring riding season and I have heard a lot about methods for aligning the forks/wheel, but do not see an official procedure in the Yamaha manual. Can you point me to it?

Thanks

 

[TownsendsFJR1300]

*** Sorry for the Thread-jack ***

Scott, I am about to replace the fork oil in prep for spring riding season and I have heard a lot about methods for aligning the forks/wheel, but do not see an official procedure in the Yamaha manual. Can you point me to it?

Thanks

Actually, its on page 4-49-FORKS of the [B]07-09 Yamaha manual[/B] in detail, page 4-9 for the front wheel/axle. Didn't see it in the 04-05 manual.

PM sent

 

[FinalImpact]

?? How is bent axle going to make a rotor wobble in and out??

Its like an all or nothing scenario. If said axle were bent it *could* make the rotors drag on the caliper all the time. It would not be a hit or miss thing as the axle is fixed and is not rotating.

Some event happened, so the question is; what components are damaged? What needs replaced? Did you try to remove the wheel w/out removing the calipers first? IDK...

 

[TownsendsFJR1300]

Something I mentioned earlier and had a similar experiance with (possibly related)..

On my old KLR, there's a separte roller bearing in the rear sprocket hub (like the FZ). One day I noticed my rear sprocket visably wobbling (about the same as yours). After pulling it apart, the bearing turned fine but was definitly the culprit. Sticking the bearing alone on the axle, you could barely see/measure any runout. Obviously, the farther out you go, the more run-out you'll have

A new hub bearing solved the problem, sprocket ran true again. It should be noted that I did not hit anything, nothing unusual, etc.

Should you have a front wheel bearing gone bad, it could very well be causing the wobbling, especially since your getting the approx same amount of deflection on both rotors.

 

[vettrick]

Final diagnosis: I pulled the front wheel off last night and looked at it today. The left front wheel bearing was totally gone. A couple of the ball bearings were out of the race and were riding against the middle spacer. The right bearing was in perfect shape. This caused the wheel to wobble and the disks to screw with the caliper pistons. I don't think the wheel is damaged...but it was close. I had to use a Dremel tool and a chisel to get the outer race out of the wheel. So I will order new bearings and a new spacer. Hopefully the disks are OK.
Thanks all for your help on this.

 

[TownsendsFJR1300]

Final diagnosis: I pulled the front wheel off last night and looked at it today. The left front wheel bearing was totally gone.
Thanks all for your help on this.

Excellent!!! :thumbup:

Took a couple of posts but nailed it!! As noted previously, nothing unusual happened when my hub bearing went out and caused the wobbling. Apparently the same for your bike.. :thumbup: