Help with my front brake system (leaking and spongy)

[zalle]

Hi,

My 1992 K1100LT just came back from BMW. They say it needs a new master cylinder and oil hoses. I asked about a repair kit for the master cylinder, and they say it won't work because mine is a '92 one, which means it's not anodized aluminium. Only a new one will work they say.

It leaks some oil from the front brakes, around the pads... Help!

Do I really need a new master cylinder?

[Martin]

Slightly confusing leaking around the pads has nothing to do with the master cylinder leaking. I honed my 92 K75's master cylinder a few years ago, it's been fine since, I don't know whether they are the same construction. However you need to be careful, and if there are deep scores a replacement is called for. A good second hand one might be able to be sourced. Locally we have a guy that sleeves master cylinders makes new pistons cost is $200.00 Au replacement cups are $10.00 once done. He guarantees his work and will send overseas, A couple of inmates have had bad experiences from sleeved cylinders in the US.
Regards Martin.

Boots and cups supply[1].jpg (58.04 kB . 768x576 - viewed 402 times)

[Chaos]

If the master cylinder is leaking, sometimes simply taking it apart and cleaning the seals cures it.  Leaking around the pads you may be looking at rebuilding the calipers.  New lines are a good idea for a 26 year old bike even if everything worked perfectly. 

[zalle]

So, maybe my best bet is to take the whole brake set (master cylinder + calipers) and just ask him to open everything and then tell me what I need, or if I just need new hoses and a rebuild...

OR, should I buy some rebuild kit (s) beforehand?

[Martin]

I'd pull them apart and see what I needed.  I don't know what the second hand parts availability is in Portugal  but there should be heaps of second hand parts in Germany as long as the postage is not too dear. :dunno
Regards Martin.