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MOTOBRICK MARKETPLACE => FS WTB WTT ~ Bikes ~ Parts ~ Gear => Topic started by: MichaelMandel on March 14, 2016, 02:34:21 AM
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As stated, looking for a rear master cylinder(brembo, Non-ABS) or a master cylinder rebuild kit for my 1985 k100. Don't have much money, just looking to have my rear brakes back working on my free bike.
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Try the Beemer Boneyard about the cheapest kit around.
Regards Martin.
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Have you looked at your master cylinder to identify the problem? Is it a corroded bore that allows fluid to leak back past the piston seals? Or are the seals bad?
On my master cylinder the corrosion was in the form of a shallow groove running for part of the length of the cylinder at the lowest point of the bore. You need to take the cylinder apart and look inside with a good light and a magnifier. Took me about a half hour before I could get everything so I could see the damage in mine, but then, I don't have such good eyes anymore.
If it is the bore you can send it out to be sleeved. I had mine done for something like $100 which is a lot less than a new cylinder. Can't think of the place that did it off the top of my head, but they were someplace out in Cali. Found them on the internet. If the corrosion isn't too bad I have heard of guys cleaning up the bore with a bit of wet or dry wrapped around a dowel. Don't go too coarse or the roughness will eat the seals on the piston.
Another option is eBay. There seems to always be a master cylinder or two on there. Try to get the seller to guarantee that it works so you aren't getting stuck with another bad one.
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Definitely check for pits or scoring before ordering a kit. I use stainless wire wool on split shaft on the end of my drill, move in and out while spinning it slowly. If you do end up putting a kit in it, stick thick silicon grease in the boot it stops the crud getting in. Occasionally you can get away with a clean and new fluid, but carefully examine the old cups for damage before you try this. Regards Martin.
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Not aware of anyone in the states selling rebuild kits anymore(or at least until stock runs out).
Breembo, and I also believe Magura are not able to sell(bmw specific spec parts) to non-bmw dealers anymore(result of a lawsuit, isn't america great.) And unless you have a real good "in" with a dealer most are not willing to sell you brake rebuild components for you to do your own rebuild. They want to sell you the whole thing, or you let them do the rebuild.(also for their own liability issues)
You can still get rebuild kits for calipers and master cylinders from Motobins.
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As stated, looking for a rear master cylinder(brembo, Non-ABS) or a master cylinder rebuild kit for my 1985 k100. Don't have much money, just looking to have my rear brakes back working on my free bike.
Is it leaking, seized or both, Michael?
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I bought a re-build kit this fall from Ridewest BMW. You should be able to find one.