Brake reservoir hose inner diameter

[keelerb]

84R100RT - I need to replace the hose from the rear master cylinder reservoir to the master cylinder - anybody know what inner diameter is? I'm hoping to score a suitable replacement from the local Auto Zone or the like. Thanks.

[skiteach]

Inner dia shouldn't matter, once it's full of fluid the orfices in master and slave will only allow x amt of fluid. Fitting sizes are much more critical- we are talking of retaining fluids at around 18,000 psi, give or take. I have seen pressures @22,000 psi, car foot brake.

[sumran]

Is the hose you are talking about under pressure or are you talking about the supply line?

It looks like cloth covered fuel line, though it may be a different size or material. Glad you asked because mine looks a little crusty. I'll be happy to learn along with you.

[keelerb]

I meant the supply line (better term) from the reservoir to the MC - not under pressure, just a rubbery inner core covered in cloth. Thanks

[keelerb]

PS I believe it may be different than fuel line as most (perhaps not BMW's....) fuel lines will break down when used with brake fluid .... you can actually see them "sweat" the fluid during the process.....

[lkchris]

Know of any other automotive applications running brake fluid through a hose this size?

Didn't think so.

But, you think PepBoys will have what you want.

Get the proper hose from a BMW dealer.

[sumran]

Good news. The hose is cheap. Less than five bucks. If yours is out of service and there is not a dealer near you, you may be on the hunt for a temporary solution.

[keelerb]

Chris and Sumran, you're both right. I've ordered the part, should be here tomorrow. "Mail" order is faster than trying to find a dealer around here. I was hoping for a temporary expedient to get me out today, but no such luck. So I went anyway - who needs a steenking' back brake anyway.

And of course, went out to the bike, turned on the fuel taps, and soon noticed fuel dripping off the left carb - fuel lines I think; ordered them too.

It never ends. Good thing I love this bike.

Thanks folks.

[skiteach]

Sorry! It was early and I didn't catch the reservoir to master part.