2CV Brake upgrade

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PeteB

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Tadpole
Tadpole
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Hi All

Does anyone know if it is possible to upgrade the front drum brakes on a 1981 2CV to discs? Any kits available etc?

Thanks, in advance,
Peter
 
Its certainly possible. Though, due to the incompatible brake fluids you have to change over all the seals. Most importantly, you also need a gearbox that has the disk brake mounting bosses.

I don't think you'd find any kits
 
Thanks Ian, guess it was a newbie question. So the drum brake systems are LHM?
 
LHM is a million times better than brake fluid. If you convert it to LHM, you'll probably never have to replace a brake component ever again (sort of pads of course). As nothing will corrode out while sitting.
 
there is nothing wrong with properly adjusted and maintained drum brakes.
 
The only reason I'd upgrade ... is to get the LHM version of everything. that way you never need to worry about brakes again. they will not take up moisture and seize up.
 
Hmmmm, LHM brake systems are not immune to moisture issues.

Moisture can still enter the reservoir as vapour, then condense, then seek the lowest point..... in this case it's the brake caliper cylinders.
Under prolonged heavy braking this little puddle can reach boiling point, and the steam created will push your fluid out of the system.
Next application will not do much.

I witnessed this during my survey run through the Vic alps, for the 2012 Raid. I was in my 1960 18hp, brake fluid, drum brake Raid car, while my accomplice was in his more modern LHM disc brake 2cv.
Halfway down the Tom Groggin track he called over the radio that his brakes had gone......
I advised him to use 1st gear and the parking brake until we could safely inspect it.
It turned out that he had not been going in low gear, and had been on the brakes all the way down the mountain.
 
SuppleC said:
Worry wort!
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Yes ... and no. I've had this before in an old CX I was driving "enthusiastically" (ok, ok, I was racing my brother at "considerable speed" to a relatives house .. he was driving a fuego). I lost brakes and cruised through a stop sign a block from the destination (it was a car I'd only just collect a few weeks before). Obviously I investigated this. I found black watery black "stuff" in the front brake lines. I bleed through clear green fluid and it was good as new. I'd boiled the moisture in the lines.

I'm betting those brakes hadn't been bled since the car left the factory quite a few decade prior :clown:

So I get where Bob is coming from. Still, I believe anything LHM should last "forever" compared to something running brake fluid :)
 
The downfall in a 2cv of LHm is overheating as the boiling point is lower than brake fluid. The brake cooling ducts don’t seem to help that much
 
PeterMol said:
The downfall in a 2cv of LHm is overheating as the boiling point is lower than brake fluid. The brake cooling ducts don’t seem to help that much
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Can you boil LHM? I have never experianced such a thing. I've "heard" you can brake a Citroen CX from well over 200km/h ... and not boil the LHM in the lines. :whistle: , er, "apparently" it brakes hard and straight from 220km/h easily. Here is the thing though, pick a spot you think you will stop easily by .... and watch as it flashed by well your still way into 3 digit speeds :eek:

if you have good clean, bright green LHM in the 2CV, I can't imagine a scenario where you would boil them. I know someone with a very "hot" CX turbo with a diesel gearbox fitted. From "high" speed, he says the brake pads melt and the warning wires fall out and the discs crack. Fancy aftermarket slotted brake rotor explode :eek: ... He has never mentioned the LHM boiling though (I can't imagine your trying to brake a 2cv from "exteme" speeds like him) :)

seeya,
shane L.
 
I saw it on the mountain raid, comming into Jenolan caves on a long steep downhill with my Dyane with drum brakes, short sharp braking in low gear with no problems, one or even two disc brake (LHM) 2cv lost brakes and took to the scenery. One owner got such a fright he went home.
I ran my Dyane on 2 raids, over 10,000 km with drum brakes, when I got home and checked the shoes they were fine. Never felt short of brakes. When i built the car before the first raid I put in new cylinders and shoes and didnt have any problems.
 
petermelb said:
I saw it on the mountain raid, comming into Jenolan caves on a long steep downhill with my Dyane with drum brakes, short sharp braking in low gear with no problems, one or even two disc brake (LHM) 2cv lost brakes and took to the scenery. One owner got such a fright he went home.
I ran my Dyane on 2 raids, over 10,000 km with drum brakes, when I got home and checked the shoes they were fine. Never felt short of brakes. When i built the car before the first raid I put in new cylinders and shoes and didnt have any problems.
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Had the brakes ever been bled though? Was it clear bright green LHM in the lines, or black, watery stuff that was LHM 20+year ago :blackeye: Please don't take this as an attack, I'm really interested to know (its possible they do not know and never checked I guess, so you probably can't answer this).

poeple change and clean brake fluid (even if its just because its rusted out the slaves). but never touch the LHM. So its highly likely these cars had the LHM in there brakes they left the factory with decades ago!

Liek you say, you fitted new brake cylinder, so change the fluid. If that car was LHM, you wouldn't have needed to change the brake cylinders... So would the fluid have been changed.... I bet I wouldn't have :clown:

Maybe before raids, ask everyone with LHM cars.... Has the brake fluid ever been changed on this ? if you don't know, it probably hasn't :)

Remember the BX16vavle did bathurst .... no boiling brakes. that would have to be the most torturous event you could ever put a brake system under :)
 
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Oh ... now I think about it ... The LHM in my mothers 2cv would certainly be the LHM it left the factory with. I'd never thought about that before. I might "borrow" it for a weekend at some point and change that LHM :clown:
 
I've never specifically changed the LHM on a hydraulic citroen, but having said that, sphere changes and leaks would have progressively diluted the older LHM over time.

I guess the application of LHM brakes 2cv is different from the large Cits, in that the LHM is purely used for brakes and is not circulating or getting heated by the suspension.

Would be interesting to see if there is indeed any water in the lhm when you change the fluid on the 2cv, Shane. Any easy test would be to put a little in a hot old frying pan and see if it spits. Or a lot in an old saucepan and see if it bubbles/pops like wet chip oil.

Cheers,
Andrew
 
andrewj said:
I've never specifically changed the LHM on a hydraulic citroen, but having said that, sphere changes and leaks would have progressively diluted the older LHM over time.

I guess the application of LHM brakes 2cv is different from the large Cits, in that the LHM is purely used for brakes and is not circulating or getting heated by the suspension.

Would be interesting to see if there is indeed any water in the lhm when you change the fluid on the 2cv, Shane. Any easy test would be to put a little in a hot old frying pan and see if it spits. Or a lot in an old saucepan and see if it bubbles/pops like wet chip oil.

Cheers,
Andrew
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The brakes don't circulate on any Citroen I know of. Bleed the brakes!!!! I bet you get black, moisture filled "stuff" come out (I have no doubt a 2cv is worse as moisture will just drop to the lowest point. In a hydraulic car it may well get boiled off as the hydraulic system heats up :unsure:

When I bleed the hydraulic cars, I usually bleed into a glass jar ... until I get bright green fluid through. I'm not bleeding air out, I'm bleeding the probably 50year old fluid out of the brake lines!

You could change the cars LHM annually .... but if you have never bled the brakes.... You still have 50+ year old LHM in them :eek:
 
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