As some of you know, I'll be replacing the gearbox in Russ's old Ami soon. The thing is, I have a disc brake box in the shed ... I don't know if you can get Ami6 brake master cylinders for LHM fluid, and I really can't be arsed changing all the seals and the rear slave cylinders, but I'd be tempted to fit disc brakes if there was a way to rebuild the callipers to accept "normal" brake fluid. Can this be done?

dot 4 seals for disk calipers?

Dot 5 (silicone brake fluid)

May Sixer has got a 2cv disc box build in by the previous owner, and has a green system and master cilinder.
Also the rear rubbers of the car are changed with LHM-proof ones.

Don't know if callipers can be changed to DOT-fluid. If so, only the rubber parts need to be changed. Those are the O-ring between the two halfs of the calliper and the ones in the hole were the pipe goes in.

Tom,
surely the main seals on the pistons are the most important consideration?

Many years ago, there was an article published in 2CVGB magazine where someone thought that they could simplify things when wanting to fit a disc brake gearbox into their drum brake Mehari, so they'd filled the system with silicone brake fluid but kept the original seals in the calipers.
By the time that the magazine had been printed and I'd contacted the Editor to suggest that the Mehari owner should drain the silicone fluid out of the calipers asap, it was too late as the seals had already swollen and the pistons were jammed.

In one of the ECAS catalogues, there's also this warning...
" If, by mistake, you put synthetic fluid into a system made for L.H.M. the synthetic fluid sinks to the bottom immediately, it will destroy seals very quickly if not flushed out with
copious quantities of L.H.M.
You can NOT use silicone fluid in an L.H.M. system. "

ken.

That is correct if the system is not flushed with white spirits. I fitted a disc gear box on a raid 2cv AK 400 (drum machine) Owner didn't want to replace master cylinder and rear wheel cylinders etc. Today the AK 400 is still running on Dot 5 silicon in the calipers and no reports of failing some 8 years later.

had a racer in our pits 3 yrs ago with dot 5 silicone as its supposed to be fade free etc etc

and to put it in the venacular it was pishing out EVERYWHERE

so your saying its a reaction between any remaining lhm and silicone? thats why flush it with white spirit??

Spot on Sean

You're right...
My bad. On my car the whole rear brake cylinders are replaced with LHM ones

Interesting. So basically, I need to flush out the entire system - including the callipers - with white spirit once I've got the gearbox in and the brakes hooked up. Is that it?