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Old 04-12-2013, 08:05 PM   #1
trc.rhubarb OP
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Brake noise question

38k and change on my 75 R90/6
Since I picked it up about a month ago, I've been chasing a strange noise.
I thought it was the speedo at first because it makes a scratching noise that sounded like the cable was too deep,
I couldn't find anything wrong with the speedo cable (ran it with a drill both in and out of the gauge) so I disconnected and rode the bike around the block.

Same noise getting faster with speed. I pulled the brakes apart and found nothing wrong that I could tell. All looked good. Put it back together, and noise was gone! Awesome, musta been crud. Next day it was back.

So this has happened 5 or 6 times, pretty much any time I feel like playing with the brake to see if I can find a problem.

Makes a rhythmic grinding noise that gets faster and faster. Sort of a click, scratch for just a small portion of the wheel rotation. Makes no noise on the center stand, wheel bearings are smooth and look to be fairly new. The fork lowers don't touch the disk.

Disk is someone's drilled aftermarket semi floating... its got pins but you can't move the disk around.

Anyone experience this before? I can't find anything wearing and the bike runs/stops as well as expected but it bugs the hell out of me

Stock ATE caliper, EBC FA22 brake pads. No o-ring on pad (could this cause it?) but the spring clip is there.
Piston is clean and moves smoothly. Disk doesn't appear to be warped and the tire spins freely when in the air without any tight spot on the brake.


*edit* If I pull the front brake, the noise goes away while the brake is engaged
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trc.rhubarb screwed with this post 04-12-2013 at 08:23 PM Reason: added more info
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Old 04-12-2013, 08:22 PM   #2
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Are you sure it's the front end making the noise? It can be deceptive sometimes.
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Old 04-12-2013, 08:23 PM   #3
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If I pull the caliper off and reinstall, the noise is gone for a bit.
If I pull the front brake, the noise goes away while the brake is engaged - yes, I forgot to say this above.
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Old 04-12-2013, 08:29 PM   #4
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Originally Posted by trc.rhubarb View Post
If I pull the caliper off and reinstall, the noise is gone for a bit.
If I pull the front brake, the noise goes away while the brake is engaged - yes, I forgot to say this above.
Fair enough. I only asked as I've chased odd noises that weren't where they sounded to be.

Are there any score lines in the face of the pads? That might indicate a small burr on the disk. If that's the case you could put a bit of 800 grit emery paper between the disk and pad and spin it a couple of times to clean it off.
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Old 04-12-2013, 08:40 PM   #5
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That's exactly what it sounds like but the pads look brand new. I'll try hitting the whole disk with a flat bar and sandpaper. Good idea on the burr.
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Old 04-12-2013, 09:17 PM   #6
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Don't get too excited with it. I don't want to be yelled at for taking a years wear off the life of your disks and pads!

I always though floating disks were supposed to move, too. Is there a chance that's got something to do with this?
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Old 04-12-2013, 09:44 PM   #7
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I've got more pads anyhow This is my first airhead and I didn't know the pads were wedge shaped. When I got the bike, I thought they were that way because the caliper was misaligned (which it was) so ordered more. Imagine my surprise when they looked exactly the same

I wont hit it with a grinder, I'll just try to smooth it some. As far as the 'floating' I've seen full floaters that move a lot and 'semi-floaters' that seem to really just be 2 different materials attached together.
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Old 04-13-2013, 07:32 AM   #8
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hmm, no change and no burrs found.

I guess I'll keep messing around with the font end. I might pull the caliper and go around the block just to rule out anything else on the front end that activating the brakes could move enough to mask.
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Old 04-13-2013, 08:16 AM   #9
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Do you feel a pulsation when you apply the brakes ? If so then the rotor might be warped.
But remember that the pads have to be in close proximity to the rotor in order to be effective when you initially apply the brake. The piston seal is supposed to pull the piston back when you release the brake, if there is brake dust/crud build up between the piston and the bore that won't happen.
My suggestion is to remove the caliper, extend the piston a ways and remove the build up of crud and dirt.
This will also reveal rust on the piston that could be the cause for sticking.

So, check the rotor for being warped, clean the piston and check operation.
Maybe take a scotch brite pad on a flat block and 'clean' the rotor.

Kai Ju screwed with this post 04-13-2013 at 08:56 AM
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Old 04-13-2013, 08:45 AM   #10
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So, check the rotor fro being warped, clean the piston and check operation.
Maybe take a scotch brite pad on a flat block and 'clean' the rotor.
No pulsing, Rotor visually (when watched against close reference points) is true. I don't have a micrometer to measure with.
I did check the caliper but didn't push the piston out very far. It looked good but I'll check again. I could have missed something.

What's really strange to me is that I can't replicate this with the front tire elevated. I can't do it while pushing the bike either. Sitting on it is the only way and happens in any gear or neutral with engine on or off. Lightly engaging the front brake while moving will make it go away for as long as the brake is engaged.
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Old 04-13-2013, 09:40 PM   #11
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I might pull the caliper and go around the block just to rule out anything else on the front end that activating the brakes could move enough to mask.
Just push the brake pistons in, so the pads are well off the disk. This way if you need the brake you simply pump the hand leaver untill the pressure is up.

How are the wheel bearings? No play - side to side at the rim?
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Old 04-14-2013, 10:05 AM   #12
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So life has jumped in the way of me taking this any further this weekend. I might get time tonight.
I appreciate the suggestions, I have a lot to try.

I'll get back to everyone once I've had an hour to spend in the garage.
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Old 04-16-2013, 07:11 PM   #13
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ok, so finally got to play with it.

The issue I'm having is that the pad on the piston side (outboard) is rattling when the piston is retracted. It gets a little cockeyed and touches the disk and/or clunks on the caliper.

There is nothing securing it in place except the little raised areas on the backing plate. I can't find any references to an oring, clip or glue/grease that is to be used to secure it and honestly, it seems fine until subjected to the road.

I can silicone it in place but it seems a hack thing to do. Is there something I'm supposed to have there?
I can take apart again for pictures but I imagine everyone knows what I'm talking about.

Thank you!
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Old 04-16-2013, 07:42 PM   #14
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Quote:
Originally Posted by trc.rhubarb View Post
ok, so finally got to play with it.

The issue I'm having is that the pad on the piston side (outboard) is rattling when the piston is retracted. It gets a little cockeyed and touches the disk and/or clunks on the caliper.

There is nothing securing it in place except the little raised areas on the backing plate. I can't find any references to an oring, clip or glue/grease that is to be used to secure it and honestly, it seems fine until subjected to the road.

I can silicone it in place but it seems a hack thing to do. Is there something I'm supposed to have there?
I can take apart again for pictures but I imagine everyone knows what I'm talking about.

Thank you!
Yes! On the nipple on the backing of the pad is an o-ring.

 photo clip_zpscb319435.jpg
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Old 04-16-2013, 07:44 PM   #15
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There is an o-ring that goes on the pad which goes in the piston. The microfische shows the o-ring on the outer pad with the clip - but that is not the location of the o-ring. IIRC, the o-ring is a M3x1.5. The last time I changed one, a metric o-ring set from Harbor Freight had the correct size.

The described use of the o-ring is to keep the pad on the caliper piston when removing the road wheel, but keeping the pad in position also applies. The outer pad, which is adjusted using the notorious eccentric bolt, has the metal spring clip. Good luck!

Stan_R80/7 screwed with this post 04-16-2013 at 07:50 PM Reason: spelling
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