Brake Master Cylinder Blanking

[malcolm]

For my Gordini I want to fit a remote servo and a remote brake reservoir. Finding the parts is driving me crazy.

The master cylinder is the early single circuit type, and as I only need one feed to the remote servo I need to blank off the other two outlets. They are 3/8 UNF to take female brake pipes (the wrong type for blanking with bleed nipples). Any ideas for blanking would be much appreciated as I haven't been able to source blanking plugs. I'm thinking of having something machined up.

The remote reservoir is needed because the carb gets in the way of filling. The thread appears to be M16 * 1.5mm, and a rough plan was to find a hose tail to convert to 6mm ID pipe and then back again. I've not been able to find these either (I can use an adapter to BSP thread, or just fill with a funnel and hose so it's not a big issue).

Any ideas for places to look for any of this would be most appreciated. I've been trying to figure this out for months and it's really holding up the project. I even wasted a fortune on a different master cylinder aimed at kit cars, but that can't be made to fit properly and has me in a bad mood.

 

[Steve Hennessey]

Any photos please Malcolm - not sure what you mean by female brake pipes. Usually master cylinders feeds take male fittings. Easy to make some blanking plugs in your own workshop it that's the case.

 

[malcolm]

Sorry, bad description. It's a normal Renault 4 master cylinder and the outlets I want to block would take male 3/8 unf fittings with a double flared pipe. (Double flared is what I meant by the female thing - if they were single flared I'd use bleed nipples).

 

[ggcton]

Sorry, bad description. It's a normal Renault 4 master cylinder and the outlets I want to block would take male 3/8 unf fittings with a double flared pipe. (Double flared is what I meant by the female thing - if they were single flared I'd use bleed nipples).

Having the same problem with fitting the servo in the R8 the solution done by others is to machine some bolts to blank off.
Gary

 

[malcolm]

I'm leaning the same way. And I have a lathe! Presumably they use a drill bit and then a grinding bit with the correct taper? Do you know what they used or have a reference you could link? I'm always worried with brakes - it's not about them leaking as that can be found out with a steady push on the pedal, more the hassle of getting in there to correct the leakage once everything else is in place.

 

[angel]

I had thought a simple trick in the past when I needed to blank an outlet from a 4-way union. I put a suitably sized steel ball from a bearing in the hole and then screwed on a pipe union without anything on it. It worked very well (and is still working).
However, this union was to be used with "bubble" pipe flares. On our master cylinders this would not work as there is the protruding "nipple" for the double flared pipe. This can be ground off with a drill, and at the same time the correct "inside" taper machined in the hole.

As you have a lathe, wouldn't it be easy to machine a M16x150 hose tail for the remote reservoir?

 

[bob_g]

Couldn't you make up a short brake pipe with the double flare & fitting on each end, and simply connect the two together? (or have I managed to miss the point?)

 

[Le Champ]

B & Q it Malcolm.

Cast iron blanking plugs are available in British sizes 'BSP' and are used to blank off gas fittings in 1", 3/4", 1/2", 3/8" and 1/4" however these are 'tapered' and available in plumbing section at large BQ branches. use with 'ptfe' (white) thread tape wrapped tightly into the threads. Parallel thread equivalents are used for water fittings.
Alternatively, both types are available mail order from 'B.E.S' tel 0800 80 10 90.
You may also be able to simply use bolts of compatible thread in conjunction with ptfe sealing tape.
Hydraulic blanking plugs were usually machined from brass and sealed with Stag compound type A (new fittings).
You could even 'mig up' the unwanted orifice (with all dodgy bits - piston/seals etc removed first.)

 

[Steve Hennessey]

Ok Malcolm - I see what you mean. I have already carried this mod out before. Double flare a short piece of copper pipe, attatch the male connector, cut the pipe off level with the end of the connector, braze the open end up to seal it and you now have your 'plug'.

 

[malcolm]

Many thanks for all the suggestions - I really was stuck thinking there must just be a bit I can buy.

I tried an old master cylinder this morning - a metal drill is nearly the right taper, and I reckon I can get a good seal by drilling and then using a bleed nipple for the blank.

For the adapter I'll put an old M16 bolt in the lathe and see what happens.

 

[malcolm]

The lathe didn't go well - mostly because I couldn't find an M16 fine bolt that wasn't hardened.

Instead I found that a fuel pipe was a good fit inside the original base for the reservoir. I compressed the pipe to expand it once in place which ought to give a good seal, then flared the end to make sure it can never pull out. I'll pressure test before fitting it to the car to be on the safe side.

PS Bob - connecting the two unused connectors with a pipe would have made it difficult to bleed air from the system. Looks like the bleed nipples are making a good seal. Fingers crossed.

 

[iancr900]

http://www.holley.com/types/Caps and Plugs.asp are these any use?