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Disc Brake button replacement

kbasa

Well-known member
So you have an early Oilhead with the buttons to provide the floater action. Your bike's got about 50 or 60,000 miles on it and the front discs are rattling like a baby toy. What to do, what to do....

Well, the answer is that the buttons that hold locate the disc on the carrier are all worn out and they're allowing some amount of rotational play. You can fix this in your garage in a couple hours. Here's how.

First off, take off the front wheel. I got mine off and dropped the wheel on top of a milk crate. You don'twant to drag your nice rotors on the ground.

270087-M.jpg

The milk crate fits perfectly

Next thing is to make sure you can put everything back together the way you found it, only with new buttons. This means ensuring that the disc is in the same relative position on the wheel and the carrier and disc are in the same relationship to each other. You'll also notice that there are two kinds of buttons. Some have a smaller hole in them. These have a circlip running around the outside. There are three on each side. Mark their location as well. I used a Sharpie pen.

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I used an arrow to point to the valve stem and the single line indexes the carrier and rotor. I put little arrows at the three special buttons so I knew where to put the replacements

There are six allen head bolts that are not reusable holding the carrier onto the wheel. Once you get them off, flip the disc/carrier assembly off and here's our mission.

270079-M.jpg

We need to get these little guys off

I used a small screwdriver to get the E-clips off. I wedged it in the little gap and then twisted the screwdriver to lever the clips off. Go all the way around, taking all the clips off.

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Just wedge the end of a teeny screwdriver in there...

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...and give it a little twist. Be careful not to scratch the disc.

Once you have all the clips off, the regular buttons will all fall out, leaving the circlip ones behind.

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Just the three circlip buttons are left behind.

I gave one of the circlip buttons a knock with a hammer and drift and it fell right out, which let the other ones go free.

Now comes the trickly part, putting the new circlip buttons in. I found the best way to do this was to make sure the little wire was in its groove and then poke the ends into place. This let the button snap into place easily.

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Make sure the wire is seated in the groove on the other side and then use your little screw driver to poke the ends into place.

After you have all three of the wire equipped buttons in place, carefully lay the disc assembly down and put the washers and new clips on. I used a small drift and a hammer to drive the new clips on.

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After you've got the three set, move on to the regular buttons, working in three segments.

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Put the new buttons in three at a time. Drive carefully with the punch so you don't scratch anything.

Now, mount the disc back on the wheel, indexed properly. Flip the wheel over and do the same thing for the other disc.

Here's what BMW calls the parts you'll need.

You'll need:

  • 18 each "9-bushing"
  • 6 each- "Roller"
  • 24 each - "9-circlip"
  • 24 each - "9 Washer"
  • 12 each - "Braker Rotor Botl - FR"
  • 12 each - "Washer"

This whole process shouldn't take you more than a couple hours.

I only have the part numbers for a '94 R11RS, but if you want them, I can send them to you.

Dave
 
How about this...

Why not start at one button and replace them one for one going around the rotor? This way you don't need to mark which is which and what goes where. Or is there something I missed that requires the two peices be seperated?

MarkF
 
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Re: How about this...

oilhed said:
Why not start at one button and replace them one for one going around the rotor? This way you don't need to mark which is which and what goes where. Or is there something I missed that requires the two peices be seperated?

MarkF

I thought about that, actually. I like to work with one set of tools at a time, so I did disassembly and then reassembly as two completely separate phases.

dave
 
Thanks for the procedure Dave! Have you guys changed wheel bearings on that bike yet? Both of our RS's needed new wheel bearings around 50K....
 
jdiaz said:
Thanks for the procedure Dave! Have you guys changed wheel bearings on that bike yet? Both of our RS's needed new wheel bearings around 50K....

I haven't done wheel bearings yet, but it's getting a new master cylinder and new pads along with the buttons.

The bearings seem OK, wheel spins freely without play and spooky noises.

I think I'm going to document the procedure for getting the master cylinder replaced as well. There were two tricky parts; getting the heated grips off and getting the rounded out allen bolt that is the pivot pin out of the master cylinder.
 
Well....

There were two tricky parts; getting the heated grips off and getting the rounded out allen bolt that is the pivot pin out of the master cylinder.

So far anyway. :brow

He hasn't done reassembly yet. We need two more parts, and the dealer doesn't open again until Tuesday.:banghead
 
KBasa said:
There were two tricky parts; getting the heated grips off and getting the rounded out allen bolt that is the pivot pin out of the master cylinder.
They used all sorts of creative hardware on that assembly...my favorite is the tiny screws and nuts attaching the brake light switch. I always dropped those.

The screw that usually gets buggered up is the Phillips-drive flathead hiding behind the inside lip of the right hand grip. You have to peel the grip back to access it, and of course when you start turning the screwdriver, the shaft gets pushed off-center by the grip and cams out of the drive slot. But you turn it anyway and ream out the Phillips drive.

And there's NO way to easily get that bad boy screw out of there. Sue had a police throttle lock installed on the road once upon a time, and the dealership in Mechanicsburg messed that screw up trying to take it out.....a five-minute job ended up taking them an hour. Needless to say, we're probably not welcome back there anymore. :p
 
Re: New master cylinder??

j-budimlya said:
Dave, just curious, but why did you need to change the master cylinder??

Jim Bud

It was dribbling fluid out of the little bellows. BMW doesn't make a rebuild kit for this bike :mad , so I got to cough up $192 for a new one.

I'm going to put some pictures up to detail how that whole thing went down. The biggest issue is the connectors for the heated grips are way the heck over on the other side of the bike and you need to take the connector apart to get the grip off.
 
jdiaz said:
The screw that usually gets buggered up is the Phillips-drive flathead hiding behind the inside lip of the right hand grip. You have to peel the grip back to access it, and of course when you start turning the screwdriver, the shaft gets pushed off-center by the grip and cams out of the drive slot. But you turn it anyway and ream out the Phillips drive.

That's funny. I had exactly the same problem and finally wound up taking an impact driver to it. It popped both of those miserable screws out. I wound up buying replacements to go with the new allen head pivot pin the PO rounded out. To get that out, I used an allen wrench one size larger than the socket was pre-rounding in banged the larger wrench in with my ball peen hammer. Took it right out.
 
Here is another one. It would save members time to have a hall of wisdom for each type, oilheads, airheads, Kbikes, and F650. I dont know if we have much on vintage bikes though.
 
lorazepam said:
Here is another one. It would save members time to have a hall of wisdom for each type, oilheads, airheads, Kbikes, and F650. I dont know if we have much on vintage bikes though.

Good idea :thumb
 
It's worth noting that while the buttons do wear and rattle, that other things can cause a rattle, too.

On my bike, the big rattler wasn't the buttons, but was the brake pads, which both lacked the little wire springs which damp the pads' movement on the retaining pin. A new set of pads had the springs, and cured the front-end rattle.
 
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dbrick said:
It's worth noting that while the buttons do wear and rattle, that other things can cause a rattle, too.

On my bike, the big rattler wasn't the buttons, but was the brake pads, which both lacked the little wire springs which damp their movement on the retaining pin. A new set of pads had the springs, and cured the front-end rattle.

Adding this at the end of what Kbasa did adds to the value of the thread. It is one of the most valuable things we have, the combined experience of everyone here, and makes this site an exciting prospect.
 
This was what we did on the forum in the beginning, and I hope to bring back a lot of these by using the search feature. It is what makes the site so valuable to me. So Kbasa, when you arent plotting evil, think you could do an illustrated brake pad change? :D
 
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