Very slow leak from Brake reservoir

[suecanada]

On my 1983 R65LS...there is evidence of a very slow leak out of the bottom of the Brake reservior. The level has slowly gone down and the black paint on the bottom rim of the reservoir situated on the handlebars shows the effects of brake fluid corrosion. So it sthis the sign to replace the whole master cylinder up on the handlebars or is there some o-rings etc. that aren't up to scratch??
One other question..I have read that the black OEM brake hose is just fine...maybe Matt Parkhouse....comments on replacement...stainless or OEM rubber?

[Bob_Roller]

Hi Sue !![ch9786]
The bottom of the reservoir has a tube like extension about 10 mm long that mates into the master cylinder, there is at least one o-ring there .

You need to remove one screw from the bottom ofthemaster cylinder, it holds the resevoir to the master cylinder .
If your brake lines are original, there are 35 years old .
I would replace them, stainless lines are around the samecost of rubber lines .

[suecanada]

Thanks Bob! Wow, fast reply. I have to renew the brake fluid anyway as routine maintenance so this will give me the chance to renew the lines and check out that reservoir for 0-ring (s). Is this a big job to replace it all and also, is there any problem I need to know about the caliper or brake lines being empty of brake fluid for a period of time? I also surmise this is a good opportunity to check out the caliper itself? There's a piston in there that needs attention maybe? All round good time to check out the front brake system as a whole?

[suecanada]

I have read Snowbum's tech on brakes just now and think I'll probably stick with the old adage if it ain't broke don't fix it. The OEM brake lines I'll leave alone for now...I'll just go and see about the reservoir leak. Is there a kit to buy??

[Bob_Roller]

Here's a link to RealOEM.com, the page fpr R65's didn't break down the parts for the master cylinder .

This is for an '82 R80ST, about as close as you'll get to a bike the same as an R65 .

http://www.realoem.com/bmw/enUS/showparts?id=0349-USA-12-1982-2471-BMW-R_80_ST&diagId=32_0747

[wilcom]

the page fpr R65's didn't break down the parts for the master cylinder

At time like these I like to order parts from Tom Cutter.

I actually buy all my parts from Tom, as little that it is, with one bike, just for a little pay back for all that he gives to the Airhead Community.

He would be the most knowledgeable guy you could get on the phone to talk BMW parts and ensure you get what you needed and the guidance you might need if he thinks that a leak from that spot would indicate if it was repairable or not. He is an invaluable resource

http://www.rubberchickenracinggarage.com/

[mrclubike]

Max shows a breakdown of the MC for the LS


The SS brake lines give a firmer feel than the OEM type brake line

I changed mine because the inside of the brake line was breaking down and causing my brake fluid to turn black 

[Justin B.]

I'll second the SS lines.  I replaced all of the front brake lines on my '81 RT when I put it back together with SS lines from Moto-Bins. Really a no-brainer as they were less than what the local "Stealers" want for stock rubber!

[Tony Smith]

I'm assuming that this is a "square" brake reservoir.

If you have a round reservoir master cylinder and it is leaking from under the reservoir itself I'm sorry to say but it is a bin job, you can no longer buy new reservoirs and their method of attachment means that there is a 99.9% chance you will destroy an old one n the process of removal. Given that BMW parts sellers are still selling the round variety as a new part I find this a bit irritating.

OTH if you have a square one, the news is brighter, the tank is still available and is quite cheap. Given what sun and brake fluid do to the plastic I would buy a new tank and not just the "O" ring.

[georgesgiralt]

Hello Sue,
IMHO if you have to dismantle the master cylinder to change the reservoir O ring, it is time for a renewal of the whole brake job.
The internal piston with seals is available from the usual suspects (item # 12 in the Max fiche) and you'll find, also, renewal kits for the calipers at affordable prices.
A couple of can of brake cleaner, a can of DOT4 brake fluid, a bit of patience and a day in the shop is all you need.
You'll be surprised at the gunk you will find into the calipers and by the change in braking this renewal makes.
Of course, as it is a security item, do not process if you don't feel up to the task. But it is not rocket science either.
Ensure you get all the parts on hand before committing to the job ;-)
Have a bright day.

[suecanada]

Thank you all for your responses!