(Resolved) Abnormal wear of rear brake hanger. What have I done? Help!

[Nelly]

So you don't have to read the entire thread.
The abnormal wear was caused by a warped disk. The outer edge had become uniformly misaligned with the inner edge approx 1.5mm. When I placed the disk on a sheet of glass I didn't notice it until I turned the disk over.
I would like to thank everyone who tried to help me rectify the problem, and in doing so made me more confident and competent with a spanner.
I replaced the disk today along with the pads, brake fluid, and new seals.

Neil






On my way home from work tonight I didn't use my ear plugs and I noticed a really nasty rubbing on my rear disk. So I took it down and found this really weird wear on the rear disc hanger.

Hanger removed from guide and shot of rear wheel spacer.

At first I thought I was missing a washer? According to the Haynes manual there is no washer on the right hand side.
I was thinking that my rear wheel must be out of alignment to cause this wear.

I have not used the string alignment method because frankly I don't understand how to do it? I am the type of person who needs to be physically shown how to do something and then I have got it.

I have no abnormal tyre wear.
The bike goes in a straight line with my hands of the bars.
I am not missing any washers or spacers from the rear.
The hanger sits well in the mounting guide on the inside of the swing arm.
The rear wheel is torqued up to 120Nm as per manual.

When I loosened the wheel the rubbing was less pronounced as I was able to physically move the hanger.

 

[YZF73]

Re: Abnormal wear of rear brake hanger. What have I done? Help!

My best guess would be that either the hanger or disc is bent due to the caliper or disc being hit sometime in the past.

The disc can be easily inspected, however you would need to compare the hanger to another one to determine whether it is bent.

Not a definitive answer but hopefully somewhere to start... :thumbup:


Yamahaboyz

 

[Nelly]

Re: Abnormal wear of rear brake hanger. What have I done? Help!

My best guess would be that either the hanger or disc is bent due to the caliper or disc being hit sometime in the past.

The disc can be easily inspected, however you would need to compare the hanger to another one to determine whether it is bent.

Not a definitive answer but hopefully somewhere to start... :thumbup:


Yamahaboyz

Thanks, I cant think for the life of me what may have hit it?
Nelly

 

[Motogiro]

Re: Abnormal wear of rear brake hanger. What have I done? Help!

Does the rotor constantly ride against the section that's worn or does the rotor hit and then clear. If it hits and clears that means it not running true. Is the wheel running true? If so then your wheel may be so far out of alignment that the rotor can hit. Bearings! Or the assembly has a bent bolt. That assembly floats on those bolts check the bolt where it mates to the assembly and the assembly for excessive wear.

 

[TownsendsFJR1300]

Re: Abnormal wear of rear brake hanger. What have I done? Help!

I would check the wheel bearings first, then pull the sleeves that the rear caliber rides on (floats on).

If there's wear inbetween the caliber itself and the caliber sleeves, the caliber is going to twist (c**k) on the mounting bracket (vs float across and center itself).

Pull the rubber boot covers and clean the assembly really well, then check for play. I suspect there's some serious wear there or its seized up off to one side and isn't centering itself. It needs to be re-greased with brake grease to keep it from seizing up.

Something else to check, clean really well around the rear brake piston and make sure it retracts fairly easily back into the caliber. Not as likely the problem as the assembly SHOULD CENTER ITSELF on the caliber sleeves

Its also possible the MAIN mounting bracket (that the caliber bolts to) itself is bent but not likely, you would have known you hit something...

 

[Nelly]

Sent from my HTC Desire S using Tapatalk 2

 

[TownsendsFJR1300]

Re: Abnormal wear of rear brake hanger. What have I done? Help!

Sent from my HTC Desire S using Tapatalk 2

Literally LOL!!

 

[FinalImpact]

Re: Abnormal wear of rear brake hanger. What have I done? Help!

Judging by all that RED DUST, the bolt is loose no matter what the torque value says as the red dust is made by two mating parts moving against each under under high friction/pressure. The iron in the metal allows the particles to rust and it makes it obvious that adjacent parts are moving.

The distance from the rotor to the hub is fixed. The distance from the caliper holder to the bearing is fixed. So it looks like you lost a bearing on the LEFT side or one of the shims. Notice how it went left towards the sprocket?

Inspect everything. And if the spacers spun long enough it could wear them down but that would make a hell'uva lot a noise (very unlikely). Not that the rotor to the aluminum was silent. . .

OR - IF the caliper bracket was not in the slide that keeps it from rotating and you torque it down, that would bend it.
Hint the shaft area of the bracket (the flats where the shaft goes though) should be parallel to the opening in the bracket which mounts the caliper. Find a way to clamp it down and measure the bracket for trueness to confirm it is not bent. Placing the machined flat on a table top and measuring upwards to the calipers opening should do the trick.

And find out what was wearing to make all that red dust. How do the bearing feel when you push on them and spin them? Are they rough and notchy?

 

[FinalImpact]

Re: Abnormal wear of rear brake hanger. What have I done? Help!

I would check the wheel bearings first, then pull the sleeves that the rear caliper rides on (floats on).

If there's wear in between the caliper itself and the caliper sleeves, the caliper is going to twist (c**k) on the mounting bracket (vs float across and center itself).

Pull the rubber boot covers and clean the assembly really well, then check for play. I suspect there's some serious wear there or its seized up off to one side and isn't centering itself. It needs to be re-greased with brake grease to keep it from seizing up.

Something else to check, clean really well around the rear brake piston and make sure it retracts fairly easily back into the caliper. Not as likely the problem as the assembly SHOULD CENTER ITSELF on the caliper sleeves

I'm on board with the fact that the stuck slide(s) could bend the whole apparatus over but #1) it would have some strange brake behavior like EXCESSIVE peddle effort with little braking results. #2) it should have destroyed the inner brake pad first if the whole assembly was not able to float.

Are either of these true?

Its also possible the MAIN mounting bracket (that the caliper bolts to) itself is bent but not likely, you would have known you hit something...

Lets clarify. If the wheel was just off (just the past couple of days), then it is possible there was an assembly error in that when the caliper bracket was set into the swing arm, "IF it wasn't in that slot in the swing arm" and you still got the wheel in there, one could stick the bolt in and bend the caliper mounting bracket while torquing it. Although I find it unlikely, it may be possible.

 

[Nelly]

Re: Abnormal wear of rear brake hanger. What have I done? Help!

Literally LOL!!

I tried to respond using tapatalk. The post didn't come through????

I have taken the disk off and it isnt warped.
Wheel bearings are fine.
I have redone the alignment.

I am thinking it's the hanger that is bent? I don't know how though.
Nelly

 

[Nelly]

Re: Abnormal wear of rear brake hanger. What have I done? Help!

I'm on board with the fact that the stuck slide(s) could bend the whole apparatus over but #1) it would have some strange brake behavior like EXCESSIVE peddle effort with little braking results. #2) it should have destroyed the inner brake pad first if the whole assembly was not able to float.

Are either of these true?





Lets clarify. If the wheel was just off (just the past couple of days), then it is possible there was an assembly error in that when the caliper bracket was set into the swing arm, "IF it wasn't in that slot in the swing arm" and you still got the wheel in there, one could stick the bolt in and bend the caliper mounting bracket while torquing it. Although I find it unlikely, it may be possible.

Yeah, I was thinking along those lines? My chain and sprockets need replacing, the bracket has moved down the hanger a great deal. Could this be a contributing factor?

It's not rust on the bolts. I used a high temp copper grease to lubricate the locking bolts. The red comes from where my hand has touched the caliper. I hadn't cleaned it before taking the pictures.
Nelly

 

[Nelly]

Re: Abnormal wear of rear brake hanger. What have I done? Help!

I would check the wheel bearings first, then pull the sleeves that the rear caliber rides on (floats on).

If there's wear inbetween the caliber itself and the caliber sleeves, the caliber is going to twist (c**k) on the mounting bracket (vs float across and center itself).

Pull the rubber boot covers and clean the assembly really well, then check for play. I suspect there's some serious wear there or its seized up off to one side and isn't centering itself. It needs to be re-greased with brake grease to keep it from seizing up.

Something else to check, clean really well around the rear brake piston and make sure it retracts fairly easily back into the caliber. Not as likely the problem as the assembly SHOULD CENTER ITSELF on the caliber sleeves

Its also possible the MAIN mounting bracket (that the caliber bolts to) itself is bent but not likely, you would have known you hit something...

I did the things you suggested a few weeks ago. I didn't notice the abnormal wear then.
Or maybe I wasn't paying really close attention?

Nelly

 

[FinalImpact]

Re: Abnormal wear of rear brake hanger. What have I done? Help!

On my way home from work tonight I didn't use my ear plugs and I noticed a really nasty rubbing on my rear disk. So I took it down and found this really weird wear on the rear disc hanger.

Hanger removed from guide and shot of rear wheel spacer.

At first I thought I was missing a washer? According to the Haynes manual there is no washer on the right hand side.
I was thinking that my rear wheel must be out of alignment to cause this wear.

I have not used the string alignment method because frankly I don't understand how to do it? I am the type of person who needs to be physically shown how to do something and then I have got it.

I have no abnormal tyre wear.
The bike goes in a straight line with my hands of the bars.
I am not missing any washers or spacers from the rear.
The hanger sits well in the mounting guide on the inside of the swing arm.
The rear wheel is torqued up to 120Nm as per manual.

When I loosened the wheel the rubbing was less pronounced as I was able to physically move the hanger.

This has nothing to do with wheel alignment. If all the spacers are there, the distances are fixed. From this it leaves the most likely to the least likely.

One question: when you pulled the caliper did the disc align into the center of the caliper brackets opening? If so, that points to caliper slides not sliding. I think a stuck piston would have wasted your brake pads. A stuck slide would have wasted the inner pad.

If the wheel bearings are bad this could happen.
If the bracket got bent during its last assembly this could happen.

This is unusual so I'd like to know what caused it.

 

[FinalImpact]

Re: Abnormal wear of rear brake hanger. What have I done? Help!

So Nelly, what happened here? What do you know?

Does the caliper slide, does the piston move freely, and what do the pads look like?

That red crap - well I hear you that you applied something red, but do tell, does it really look the same as what you applied color wise?

 

[Nelly]

Re: Abnormal wear of rear brake hanger. What have I done? Help!

So Nelly, what happened here? What do you know?

Does the caliper slide, does the piston move freely, and what do the pads look like?

That red crap - well I hear you that you applied something red, but do tell, does it really look the same as what you applied color wise?

The Caliper slides and the piston moves freely. The outside pad is abnormally worn because it was dragging.
The copper lubricant is really that red. It's actually quite handy as you can see where it has been applied.
I really can't recall any issues with seating the Caliper on the guide when I did the swing arm service a few months ago, I am completely at a loss.

I can't see how the Caliper bracket could be bent as it is cast. It would snap before bending. As stated the most likely is the least likely.

Nelly

 

[TownsendsFJR1300]

Re: Abnormal wear of rear brake hanger. What have I done? Help!

Just looked at mine and I think I know what happened..

That cast bracket has a slide and rides on a notch which IS PART OF THE SWING ARM (it keeps the assembling steady and allows chain adjustments, the wheel slides forward and backward, that notch/slot keeps the brakes clocked in one position.

I'm betting when you reassembled it, it wasn't in the slot and was riding atop the swingarm. It was good until you made a fairly hard stop, then the bracket AND entire assembly, rode clockwise. The notch and slide, now working against each other, binded up and kinked sideways!


Try re-assembling making sure that notch is lined up with(around) the swingarm....

 

[Motogiro]

Re: Abnormal wear of rear brake hanger. What have I done? Help!

The Caliper slides and the piston moves freely. The outside pad is abnormally worn because it was dragging.
The copper lubricant is really that red. It's actually quite handy as you can see where it has been applied.
I really can't recall any issues with seating the Caliper on the guide when I did the swing arm service a few months ago, I am completely at a loss.

I can't see how the Caliper bracket could be bent as it is cast. It would snap before bending. As stated the most likely is the least likely.

Nelly

I was thinking the same thing. The casting may have some give but should be less malleable and prone to break instead of bend. If you measure the slot with a dial caliper or machinist scale you will see if that clearance slot has closed up. If it hasn't that slide bolt is prolly bent.

 

[FinalImpact]

Re: Abnormal wear of rear brake hanger. What have I done? Help!

I was thinking the same thing. The casting may have some give but should be less malleable and prone to break instead of bend. If you measure the slot with a dial caliper or machinist scale you will see if that clearance slot has closed up. If it hasn't that slide bolt is prolly bent.

I'd have to disagree about the casting breaking before it bends. That is not a desirable feature for brake hardware. I suspect that bracket is of better grade of aluminum than other parts because its holding the caliper.

As for the actual issue;
Likely was assembly error a while ago. Close inspection of the mating parts SHOULD SHOW CONTACT in all the wrong places. Does it?

So - review of the thread indicates you did have the wheel off recently. So this could be true?

Lets clarify. If the wheel was just off (just the past couple of days), then it is possible there was an assembly error in that when the caliper bracket was set into the swing arm, "IF it wasn't in that slot in the swing arm" and you still got the wheel in there, one could stick the bolt in and bend the caliper mounting bracket while torquing it. Although I find it unlikely, it may be possible.

Nel, maybe if you cleaned the thing up a little you could tell what was going on back there??? lol :scared:

 

[TownsendsFJR1300]

Re: Abnormal wear of rear brake hanger. What have I done? Help!

Any updates?

 

[Nelly]

Re: Abnormal wear of rear brake hanger. What have I done? Help!

I'd have to disagree about the casting breaking before it bends. That is not a desirable feature for brake hardware. I suspect that bracket is of better grade of aluminum than other parts because its holding the caliper.

As for the actual issue;
Likely was assembly error a while ago. Close inspection of the mating parts SHOULD SHOW CONTACT in all the wrong places. Does it?

So - review of the thread indicates you did have the wheel off recently. So this could be true?



Nel, maybe if you cleaned the thing up a little you could tell what was going on back there??? lol :scared:

Ha Ha, It has been raining for the last month, there is so much crap on the lanes.
It's dirty pretty much 99.9% of the time.

So an up date:
I have taken the disk of and used a piece of glass to see if the disc is true. There appears to be no warping. I do not have a micro meter or calipers so the glass was the best I could do.
The guide that the caliper runs down has no abnormal wear on it. The only thing of note is that there is about 3mm gap. The bracket doesn't sit flush with the swing arm.
Is that normal? The bolts that hold the the caliper are also true.

I recall that when I did the swing arm pivot bearings the swing arm was a total B@@ch to -re-align. Could I have twisted the swing arm? No hammers were used for the alignment just a lot of swearing and tears.

I have purchased a caliper bracket from Steve Allen and it should be here in about 10 days. I will clean up the back end and do a re-install and see whats what.

Thanks for all of the very useful input guys.

Nelly