Looking for help on diagnosing a problem with my 03 1150RT

[ednowicki]

Looking for help on diagnosing a problem with my 03 1150RT

 

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Problem:

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I’m at a stop light, (10’s of seconds wait) with the rear (linked) brake pedal engaged. I ease out the clutch and start rolling. I have a violent front wheel ‘thump’ that seems to occur about once per wheel revolution. This might last for 20 to 50 yards then go away.

 

The ‘thump’ feels like the brakes are locking up or catching once per revolution. *this is an assumption*

 

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Frequency of Problem:

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This problem started one (1) month ago, and has happened four (4) times.

 

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Maintenance I’ve done between one (1) and two (2) months ago

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• replace front brake pads

• replace front tire

• replace a missing rear brake reservoir cap. The diaphragm was still in place, the outside was contaminated but the fluid in the reservoir looked clear (clean?). The brakes feel good (hard).

• replace a leaking QD fuel line connector

 

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Troubleshooting I’ve done to date

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• remove front brake calipers and verify the front wheel rotates freely

• remove front brake pads, clean brake calipers, guide pin, anti-rattle clip, and brake pad/piston surface. Insure anti-rattle clip is properly oriented.

• verify no play in steering head

• remove front wheel, check all components (speedo, rotors, axle, torque spec)

 

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What I’m thinking about doing next

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• flushing brake wheel and control circuits (last time was two (2) year ago)

• rebuild front calipers

 

I’m assuming it’s a brake problem. Maybe that’s an incorrect assumption.

 

Any advice is greatly appreciated.

[KMG_365]

Wow, that's a head scratcher. As it was an intermittent problem that would eventually resolve I would have thought it was either an electrical or servo related issue. But considering the rear control circuit reservoir's missing cap, I might worry about contamination getting into the rear (linked) control circuit input into the servo causing a reluctance to release the rear (and thereby also the front) brake. But the "once per revolution" part doesn't seem to want to correlate with that part unless there's also a problem with the following:

 

You say you removed the calipers to make sure the front wheel turned freely, but did you check the front disks' runout? Also spin the front wheel with the calipers in place to make sure a warped rotor is not binding on the pads? Did you use brake cleaner to clean the calipers? Be sure to get all the grime off the parts of the pistons that were exposed when the old pads were worn down. Also, if you're a sporty or heavy rider, your rotors could be nearing the wear limit making them more prone to warping. When the front tire was changed one of the front rotors could have gotten bent. With the "grabbing" being linked to the rotation, I would suspect something in the wheel is the culprit. But also how long has it been since you bled the control circuits?

 

If it were me, I would:

 

1) mic all four of the rotors and check them for runout

 

2) check the ABS sensors and their wires for damage

 

3) check the ABS rings on the wheels for FOD

 

4) properly and carefully bleed ALL of the brake circuits: front and rear wheel and control (and you might as well do the clutch while you're at it)

 

5) If I had any doubt about the tire swap, I'd inspect both wheels and re-balance both of them.

 

6) While re-balancing the wheels, you should also check the rim beads for runout both ways while you're checking the rotors.

 

7) check the rear lug nuts for tightness and especially the rear wheel bearings (and paralever) bearings for play

 

8) with the bike on the center stand, key on, kill switch in "run", in neutral but not running, operate both control inputs, listening for the whine of the servos and making sure they shut off crisply when you release the lever/pedal and are not hanging up. If you frequently hold the bike by pressing hard on the rear pedal you could have a pedal/switch return issue (weakened return spring?).

 

9) confirm activation of the brake light by both controls and have someone ride behind you on the route where this occurs, watching your brake light to confirm that you're not inadvertantly riding the rear brake with your boot slightly when you start out.

 

10) invest in or borrow one of those doohickey's "Ken H." showed us at the UnRally and see if there are any error codes set that might point you to some other cause.

 

 

Do you ride with ear plugs, and are you able to hear the servos while riding when this happens?

 

Sorry, that's all I've got right now--I've gotta go to bed as I'm leaving for Torrey in the morning!

 

Oh, and:

 

11) Ride it out to Torrey and let us tear into it after a few beers Saturday night!

[ednowicki]

 

<snip>

You say you removed the calipers to make sure the front wheel turned freely, but did you check the front disks' runout?

</snip>

 

No… will do

 

 

<snip>

Also spin the front wheel with the calipers in place to make sure a warped rotor is not binding on the pads?

</snip>

 

I did this. I did not notice any ‘excessive’ rubbing, just the slight-to-medium rub of the new pads on the rotors.

 

 

<snip>

Did you use brake cleaner to clean the calipers?

</snip>

 

Yes

 

 

<snip>

Be sure to get all the grime off the parts of the pistons that were exposed when the old pads were worn down.

</snip>

 

I pushed in the pistons with my thumbs before putting on new pads. I liberally sprayed the caliper assembly, applied 80-grit sandpaper to the guide pin, and insured proper reassembly.

 

 

<snip>

Also, if you're a sporty or heavy rider, your rotors could be nearing the wear limit making them more prone to warping. When the front tire was changed one of the front rotors could have gotten bent. With the "grabbing" being linked to the rotation, I would suspect something in the wheel is the culprit.

</snip>

 

I’m assuming the rotors are fine because there is not a periodic rub when I spin the front tire, nor is there a visible warp. Also, this is a intermittent problem. I hate to make a rash assumption, but this is low on my suspect list.

 

 

<snip>

But also how long has it been since you bled the control circuits?

</snip>

 

2 years. This is on my short TODO list.

 

 

<snip>

5) If I had any doubt about the tire swap, I'd inspect both wheels and re-balance both of them.

</snip>

 

I had a problem with a avon storm st and swapped it with a bridgestone bt020. Since then the front has been silky-smooth.

 

 

<snip>

Do you ride with ear plugs, and are you able to hear the servos while riding when this happens?

</snip>

 

No, Yes

 

 

<snip>

1) mic all four of the rotors and check them for runout

 

2) check the ABS sensors and their wires for damage

 

3) check the ABS rings on the wheels for FOD

 

4) properly and carefully bleed ALL of the brake circuits: front and rear wheel and control (and you might as well do the clutch while you're at it)

5) If I had any doubt about the tire swap, I'd inspect both wheels and re-balance both of them.

8) with the bike on the center stand, key on, kill switch in "run", in neutral but not running, operate both control inputs, listening for the whine of the servos and making sure they shut off crisply when you release the lever/pedal and are not hanging up. If you frequently hold the bike by pressing hard on the rear pedal you could have a pedal/switch return issue (weakened return spring?).

 

9) confirm activation of the brake light by both controls and have someone ride behind you on the route where this occurs, watching your brake light to confirm that you're not inadvertantly riding the rear brake with your boot slightly when you start out.

 

10) invest in or borrow one of those doohickey's "Ken H." showed us at the UnRally and see if there are any error codes set that might point you to some other cause.

</snip>

 

 

I will do. Thanks for the advice

[T__]

Looking for help on diagnosing a problem with my 03 1150RT

 

-----------

Problem:

-----------

I’m at a stop light, (10’s of seconds wait) with the rear (linked) brake pedal engaged. I ease out the clutch and start rolling. I have a violent front wheel ‘thump’ that seems to occur about once per wheel revolution. This might last for 20 to 50 yards then go away.

 

The ‘thump’ feels like the brakes are locking up or catching once per revolution. *this is an assumption*

 

----------------------------

Frequency of Problem:

----------------------------

This problem started one (1) month ago, and has happened four (4) times.

 

-----------------------------------------------------------------------------

Maintenance I’ve done between one (1) and two (2) months ago

-----------------------------------------------------------------------------

• replace front brake pads

• replace front tire

• replace a missing rear brake reservoir cap. The diaphragm was still in place, the outside was contaminated but the fluid in the reservoir looked clear (clean?). The brakes feel good (hard).

• replace a leaking QD fuel line connector

 

------------------------------------------

Troubleshooting I’ve done to date

------------------------------------------

• remove front brake calipers and verify the front wheel rotates freely

• remove front brake pads, clean brake calipers, guide pin, anti-rattle clip, and brake pad/piston surface. Insure anti-rattle clip is properly oriented.

• verify no play in steering head

• remove front wheel, check all components (speedo, rotors, axle, torque spec)

 

--------------------------------------------

What I’m thinking about doing next

--------------------------------------------

• flushing brake wheel and control circuits (last time was two (2) year ago)

• rebuild front calipers

 

I’m assuming it’s a brake problem. Maybe that’s an incorrect assumption.

 

Any advice is greatly appreciated.

 

Ed, that is a strange one indeed..

 

Are your brakes pulsating or making noise while stopping for the light? If not then you probably don’t have anything warped or bent..

 

Can you hear the servo motor quit running BEFORE pull away? Maybe you have a sticking rear brake pedal.. Listen closely for the servo motor to quit operating when you release the rear brake pedal..

 

What happens if you ONLY use the front brake lever to stop for the light? Same problem of none on pull away then?

 

If you can get it to act up on a regular basis you can do some testing__

 

Maybe find a deserted road or parking light & do some stop testing.. Try stopping for the 10 seconds then walking the bike away from the stop to see if the problem is still there.. If so try walking the bike away from the stop with the ign switch turned off to see if problem gone..

 

Maybe try riding the bike to a stop with the ABS relay removed to kill the ABS servo assist to see what happens on drive away..

 

Maybe find a steep down hill & stop on that then key off & roll away from the stop.. Then roll away from stop with engine on but trans in neutral..

 

 

If problem really intermittent then look for a sticky rear brake pedal or sticking rear brake switch..

 

Can you correlate the problem to ABS brake release on the stop? (ie does it only happen after brakes ABS’d on the stop).. Sometime you can get momentary ABS wheel release while stopping hard on a bumpy or tar strip covered road surface.. If so suspect a sticking valve in the ABS controller..

 

Twisty

[Ken H.]

did you check the front disks' runout?

Yes, that's the first thought that occurs to me too; warped front rotor.

[Tipover_Bob]

Ed:

Perhaps it is as simple as contamination from brake fluid that may have spilled out of the reservoir with the missing cap. Once that is finally gone the problem may be gone too.

Tipover Bob

[ednowicki]

I’m a dumb-ass.

 

 

This morning I checked the abs ring and the true-ness of the rotors. While sitting there spinning the wheel, I would occasionally hear a slight rattle.. just every once in a while.

 

Subsequently, I tried giving the wheel a good spin and then abruptly stopping it with my hands. I heard something *inside* the tire. This is when I *knew* I was a dumb-ass.

 

When I change my tires, I use a small block of wood ( I have a bunch of them laying around) to hold the tire bead inside the rim while I walk the mounting bar around the rim.

 

The wood spacer dropped inside the tire. Tonight I pulled the wheel and dismounted the tire, and sure enough there was the block of wood.

 

I guess (4 times in a month), the wood would flop around and wedge itself against the tire/rim when I was approaching a stop. When I would roll away, the wood would keep the tire from compressing, (I’d get a thump once per revolution), and the wood would dislodge itself after a couple of wheel revolutions.

 

Jeeze… good thing I not a surgeon.

 

I appreciate all your helpful posts.

[ESokoloff]

I’m a dumb-ass.

 

 

Some one needs to give you a dope slap like in your avatar

 

Seriously, glad it was not a costly repair.

I'll bet you don't do that again.

 

FWIW I left a 3"x4" (or so) section of plastic sheet (homemade rim protector) in a tire once

[KMG_365]

Oh man, I'm so tempted to bestow upon you a new nickname . . . but that wouldn't be very nice, would it??

 

Glad you got it figured out and the chunk of wood sure makes a LOT more sense than any other ideas I posted!

[Ken H.]

Well wood in the tire certainly was not on my short list of possible causes. Glad it all worked out though!

[Tipover_Bob]

Ed:

If it's that little block of wood, I don't think so.

Tipover Bob

[ednowicki]

That is the block of wood.

 

I am (almost) certain it's the problem, but I guess I'll only know for sure after a couple of weeks.

[Green RT]

That is the block of wood.

 

I am (almost) certain it's the problem, but I guess I'll only know for sure after a couple of weeks.

 

I suggest you make sure you didn't bend a rim. Not likely maybe, but having a block of wood wedged between the rim and tire can't be a good thing. I discovered last winter that it is pretty easy to bend a rim.