'83 K100 8v non ABS

I think the rear rake master cylinder needs replacement. I have already done the brakes (new shoes), a new rake disk and a master cylinder kit. Brakes still are spongy. Bike stood for many years and there is corrosion in the master cylinder towards the back. Seems the fluid is flowing back under pressure.

I am looking at E-Bay for a replacement.

Are there rear brake cylinder bodies from other BMW years/models that will interchange? Seems the K75 and R series, as well as the newer years, are far less expensive than the early K's.

Any help will be greatly appreciated.

Thanks

Glen

Hey Glen!

There are two sizes 12 and 13 mm, they both fit.
The only new you can get now are 12mm.
I have two K 75, 1991 without ABS = 12mm 
and a other K 75 with ABS = 12mm.

All K 75 100 and 1100 will fit! I think? the R100R and R80R will fit too, but wait until somebody else confirmes.

On REALOEM klick on the rear master cylinder number and you will see which other KS use the same cylinder.
http://www.realoem.com/bmw/enUS/showparts?id=0562-EUR-02-1992-K569-BMW-K_75_85_0562,0571_&diagId=34_0620

Cheers

I've just replaced the 13mm rear brake master cylinder on my '85 K100, BMW part number 34 31 1 454 351, the same number for your '83 model. There are plenty of them available. I bought it new for less than the US$200 it retails for as I work for a dealer. No other master cylinder from any other Beemer fits the K100/K75 and works as the original does. It has to do with the piston/lever attachment. A clever person could/might be able to fab something up. The 12mm ABS version is also available and will slot into position like the non-ABS master cylinder. There is no separate piston/seal kit available from BMW.

Both Motobins and Motorworks have 13mm cylinders, which is a bit cheaper than 12mm.
Bins have the lowest price.......to post a small item like that to SA would cost only a couple of fingers.

Jip: After posting, I re measured the master cylinder, and the part that Moto Bins sent me. One is 13mm, the kit is 12mm. They made a mistake and sent me the wrong one. No wonder I've been struggling to get proper brakes. First going to look and see if I cannot scrounge the rubber piston somewhere else. Then I'll probably have to buy a whole kit again. Dammit!