Brake Reservoir

[BadAsp427]

I have a 20th Anniversary (#008) kit that I'm building. With that kit I received the chrome small brake fluid reservoir. My concern is that it seems to be a positive seal cap. If that is the case, how can fluid be sucked out of it if there is no displacement area (air) allowed into it? I understand that FF has changed this on newer builds? Is this something that can be upgraded with some new parts or something? I do not want to just "take the "o" ring out. I have to say, I'm very surprised that FF would want someone building this kind of car with this reservoir, seems kind of on the cheap side of things... I'm guessing it must work, either that or nearly everyone is spending money on the CNC double/triple reservoir system. Either way, Let me know your thoughts and what I should do. Thanks.

95576

[RRussellTx]

Not sure if this helps, but I sold mine and opted for the CNC 3-part Reservoir mainly for the safety of having separate front and rear reservoirs. I don't have the FFR version anymore to verify it, but I though the FFR reservoir had a small hole in the top and some sort of rubber baffle to allow for air displacement?

[mikeinatlanta]

Also can't help but agree that a fully sealed reservoir is not appropriate for the application. I went CNC dual. One feeds front and the other feeds rear and clutch.

[NAZ]

The reservoir has to be vented to atmospheric pressure to operate correctly BUT the brake fluid must not be vented directly to air. Brake fluid has an affinity for moisture and will suck it out of the air and affect the boiling point of the fluid. So brake fluid reservoirs should have a vented cap and a thin elastomeric bladder between the cap and brake fluid to prevent direct air to brake fluid contact.

[TheBabyBadger]

Not sure if this helps, but I sold mine and opted for the CNC 3-part Reservoir mainly for the safety of having separate front and rear reservoirs. I don't have the FFR version anymore to verify it, but I though the FFR reservoir had a small hole in the top and some sort of rubber baffle to allow for air displacement?

Should be a small hole in the cap. I went with a slim line Tilton 3 reservoir for clutch and brakes, F/R. Wanna buy another FFR reservoir? :)

[rychi1]

I had the original reservoirs like you mention but had to buy an extra so I would end up having 3 (2 brakes and 1 clutch). Factory five at some point switched between a 2 inch version like you show and a 3 inch version, so because I ordered them at different times I ended up with 3 of the each version. The good thing is that each of those have the same size cap. I was able to replace all of the caps on the original ones I had with the vented caps from the newer version. I would do a post asking if any one has any reservoirs with the vents or just the caps since so many swap out for CNC or other options. I found a few on the forums and through a mix and match made mine work, for a lot less than the CNC 3 reservoir costs.

[BadAsp427]

I had the original reservoirs like you mention but had to buy an extra so I would end up having 3 (2 brakes and 1 clutch). Factory five at some point switched between a 2 inch version like you show and a 3 inch version, so because I ordered them at different times I ended up with 3 of the each version. The good thing is that each of those have the same size cap. I was able to replace all of the caps on the original ones I had with the vented caps from the newer version. I would do a post asking if any one has any reservoirs with the vents or just the caps since so many swap out for CNC or other options. I found a few on the forums and through a mix and match made mine work, for a lot less than the CNC 3 reservoir costs.

Thanks... I'll do that...

[Brad Smith]

If you look closely at the rubber diaphragm under the cover, you'll find one or two VERY small slits in the rubber.

[BadAsp427]

If you look closely at the rubber diaphragm under the cover, you'll find one or two VERY small slits in the rubber.

Well, that is actually the problem, these reservoirs do not have a diaphragm.... That's my whole problem... I just received 2 more of them and they are strictly an "O" ring around a solid top... no venting of any kind... And FF says this is fine.

[Brad Smith]

Measure the inner diameter of the cap, and find a brake reservoir cap the same size and rob the diaphragm from it, then drill a tiny hole in the top of the cap.

[rponfick]

Very interesting discussion.

I just got the new FFR '35 pickup model and it has the same reservoir. Mine has a small hole drilled in the cap, but no "O" ring or rubber diaphragm. I am concerned also about moisture contamination of the brake fluid if it is exposed to air all the time. And, it can not be totally sealed as the fluid would never drain out. If you remember all the car stock master cylinders; they had a rubber diaphragm that would be sucked down as fluid was being used. No open air exposure.

Very interesting.

Ralph

[Brad Smith]

Actually, the diaphragm is designed to move with brake application, but as pads wear more fluid migrates to the calipers and the diaphragm would become fully extended, so there's a tiny slit in the rubber to let MINUTE amounts of air in.