Board logo

Brake cluid reservoir cap...
bigandy - 12/4/07 at 10:13 PM

evening folks.

I have just been taking a look at a brake fluid reservoir that I have bought from Rally Design, and am intending to fit to the clutch master cylinder on my car.

I have noticed that there is a slight hole in the top of the cap, presumably to vent the reservoir, and to stop a vacuum building up as the fluid level drops.

Anyway, is this hole likely to cause any problems with water absorption (into the brake fluid) or leakage at all? Is there anything that can be done to prevent this from happening and maximise the fluids working life? How about just bung the hole up with something?

Cheers
Andy

Angel Acevedo - 12/4/07 at 10:36 PM

There should be a diaphragm between the cap and the fluid, that way the diaphragm keeps air thence moisture out of the fluid.
If theres not, you may fit one.

JAG - 13/4/07 at 08:02 AM

quote:

to stop a vacuum building up as the fluid level drops


That's exactly why the hole is there. There's not much you can do about it if you want the reservoir to top up the hydraulic system every time you take your foot off the pedal.

NS Dev - 13/4/07 at 11:23 AM

rally design also sell rubber diaphragm thingies for just this purpose, they are like tiny gearstick gaiters but with no hole in the middle.