Does anyone know where you can get just the K100 (1983 2V non-ABS) front brake master cylinder seals?  I have been searching and can only find rebuild kits including piston, spring etc, and in Australia you just about need to sell the bike to buy the rebuild kit!

Any help would be greatly appreciated!

Give www.motobins.co.uk or http://www.motorworks.co.uk/vlive/Home/index.php a try.

Motorworks part number is BRA10493

MUNICH has the seals for $46.50 + postage (which is usually very quick if you need em asap, but will be Monday earliest due to ANZAC Day)
Part#
3423304RK

Thanks Rossko, but these are caliper overhaul kits - not for the master cylinder.  The only
rebuild parts I can find for the master cylinder is the complete piston and spring assembly (which includes the seals)
 and costs about $200 in Aus.  I really only need the 13mm rubber seals for the piston as the rear seal is the only worn part.

Sorry.
In my early morning haze I misread the post.

Sorry, you have to get the whole shebang with the master cylinder.

This is the part number from Motorworks BRA02356 40GBP plus 10GBP postage



No alternative. Someone obviously is making the rubber seals, but I have not heard of anyone finding out who that is.

I would never replace just one seal because there is a real good chance that you will pay it another visit in the very near future. Never take chances with your brakes it is really very easy to do it right every time.
As RossKo said the kit including all seals is the only way that I know you can get them.

Hi Rick,

I intend to replace all of the seals (if I can find them).  I don't see much need to replace the piston as it is not a wear part.  I can't find anywhere I can buy a seal kit to replace the wear parts only, and I am a bit reluctant to pay nearly Au$200 for $5 worth of rubber seals.  I can get the whole kit and caboodle from beamer boneyard for about $50 plus $50 postage, and may have to do this if I can't find just the rubber.

Couldn't agree with you more about the piston. $50 from Beemer Boneyard is probably as good as you will get.
Motobins or Motoworks would be in the same range and post seems to be a bit cheaper for the small packages from the US than UK
It's probably the only way the thieves can get rid of the hundred thousand pistons they mistakenly ordered 15 years ago.

Have you considered having a stainless sleeve put in. It's usually round the $100 mark but you probably will never have to touch it again.

I have read about the stainless sleeves but the bike is quite low KMs (45K on a 30 year old bike) and the cylinder itself is in good nick after a thorough clean.  The rubbers have probably more perished over time than worn through use, so a stainless sleeve is probably not as critical as new seals at this time.

chris ...over time the bore does become pitted .....not immediately apparent  but water does tend to  build up and find it way down there ...just the nature of brake fluid

a light hone of the bore could well help in the fix once seals are found and before fitting

good luck !

I did once put an 'o' ring under the lip of the seal to stop a leak while I was waiting for a new piston assembly to arrive.........it worked so well that I didn't replace the piston assembly for, well, quite a long time.

Of course I wouldn't recommend this, other than a 'get-you-home' bodge.

Paul.

Not a bad idea Paul.  I quite like the idea of get-you-home bodges, particularly if they work!  I have gone though hundreds of pages of seal catalogues, and spent hours looking on the net at seals of all different shapes and sizes, and have come to the conclusion that the seals I want don't exist except wrapped around a new piston.  Going to have to bite the bullet and get an overhaul kit, but I will try your idea while waiting for the new one to arrive.  Thanks.

When it comes to those sort of bits I have found that BMW don't use any special parts but sometimes very hard to find bits.
There will be some seal somewhere that is the right size but as always the trick is finding it. Often the price is no cheaper and sometimes more expensive so you waste an enormous amount of time getting absolutely nowhere.

I recently went through this same rigmarole trying to find some seals for a ZX-10R master cylinder, no one could supply even similar seals - they exist only in master cylinder manufacturing, it seems, and nowhere else. It's ridiculous that you can only buy them in a kit with other bits you won't need, but that's how it is.

sidecar paul wrote:I did once put an 'o' ring under the lip of the seal to stop a leak while I was waiting for a new piston assembly to arrive.........it worked so well that I didn't replace the piston assembly for, well, quite a long time.

Of course I wouldn't recommend this, other than a 'get-you-home' bodge.

Paul.

I have honed out the cylinder bore and cleaned everything thoroughly, and tried Paul's 'get-you-home' bodge - and it works!  Bled the brakes and they are solid and the leak has completely stopped.  I will still replace the seals when they get here, but at least the paintwork is now safe and I can put the Gladwrap away!!  Thanks Paul.

...tried Paul's 'get-you-home' bodge - and it works!...

That´s very valuable info.
Thanks both
Best regards
JAP