Changing the line from reservoir to rear master cylinder

[bofler]

Since I'm rebuilding or putting in new parts for most of the braking system, I figured it wouldn't hurt to change this crusty, old line between the reservoir and rear master cylinder.

Was thinking I would just get some cheap rubber fuel hose to run those few inches, but not sure if a special type of hose is needed. I'm no expert on brake fluid chemistry, and don't want something that's going to degrade and put a bunch of crud in my fresh system. Any thoughts?

[OldguyGlen]

I'm no chemist either. But I was comfortable using fuel rated hose. I would avoid vacuum hose or water/drain/vent type hose.

[bofler]

Well, upon further research I decided that standard rubber fuel line is not a good idea. Seems like brake fluid will probably eat it up in a relatively short period of time, leading to leaks and crap in the brake system.

Don't need a high-end, steel braided line for this, but should be something designed for brake fluid.

[johnny42]

bofler: did your research mention anything about DOT 5 brake fluid and fuel lines? I use DOT 5 and think I might replace mine line as well.

[winguyjo]

my numbers are probably not really accurate but ... braking systems operate around 2000 - 3000 psi so the lines are built to withstand those kinds of pressures.
fuel systems are generally below 100 psi ... again, my accuracy can be called into question ... but the difference is obvious. this alone should be enough reason to not use fuel line in place of brake line, and then there's the problem of possible incompatibility with brake fluid.

[bofler]

We're talking about the line that runs from the reservoir and into the master cylinder. It's before the master cylinder, so not pressurized.

[winguyjo]

d'oh !
pressure not an issue then.

[johnny42]

I did learn EPDM material is what the line should be made of. Good for most liquids/fluids. Find the right diameter and length and you're good to go.

[bofler]

Yeah, I also read that EPDM is good. Have looked for it in shops locally, and nobody has anything of that sort. I just saw a similar post in the forum where WingAdmin says that PVC hose is resistant to brake fluid and could work for this short stretch. Would be kind of cool to have some clear tubing running through there. Though, maybe I will just stick with the old hose unless something else falls into my lap.

[WingAdmin]

I've read many posts where people used PVC (in particular, translucent PVC) for brake fluid, but according to Eaton, it's not recommended. I just found this from an application booklet they publish:

Acceptable brake fluid hose material

[bofler]

Well, good to clear that up quickly. Thanks WingAdmin! Seems like a little stretch of EPDM hose is the best option. For now just going to plan on using the old one, but somehow seems wrong when I'm putting in new stuff on most everything else in the system.