LHM brake fluid (Citroen 2CV)

[TurboFiat124]

I just recently added a Citroen 2CV to my collection of oddball European cars. Well when I mean "oddball", I mean odd for the United States. My Trabant would be recognized in Germany and former Eastern Bloc countries and the 2CV in France and other countries. My Yugo is recognized by people my age who were of driving age back in the 1980s but rarely by people as young as 25.

It uses a brake fluid called LHM. I was aware that Citroens were unusual cars and for some reason knew years before I even owned a Citroen they used special fluids so it was no surprise when I noticed it had green brake fluid.

It's supposed to be a type of mineral oil.

Prior to 1982, the Citroen 2CV had four wheel drum brakes and used DOT 3 brake fluid. In 1982 they went to front discs and this LHM brake fluid. The brake fluid and the reservoir cap are green indicating not to use DOT 3 brake fluid. I read in a shop manual in a pinch you could actually use something like baby oil if you could not find LHM fluid but to have the brake system flushed when possible but would not cause any ill effects to the seals in the meantime. However if you add DOT 3 or DOT 4, it will ruin the brake seals.

Since none of the auto part stores even sell GL-4 80/90 EP transmission oil, I didn't even bother to ask them if they carried LHM brake fluid (or course they would tell me they had never even heard of it) so I ordered it from a parts supplier here in the US. At least I didn't have to have one bottle shipped all the way from Europe!

Wikipedia lists the difference between brake fluids and seems like LHM is better than DOT 3 or 4. It's got a higher boiling point and I think does not absorb water like glycol based brake fluids.

https://en.wikipedia.org/wiki/Brake_fluid

Are the brake seals in the 2CV made of natural rubber or something? Why is DOT3 bad for this type of braking system?

Are there any other companies that use this same brake fluid? it would be great if LHM could be used to replace DOT 3 because I think I read it does not absorb water like DOT 3.

Years ago I had my eye on a sweet late 80s/early 90s Saab 900 convertible parked in front of some business with a for sale sign on it at a good price. Then some guy told me to stay away from it because Jiffy Lube topped off the reservoir with DOT 3 and it destroyed the brakes. Maybe Saabs used LHM fluid?

Speaking of Citroen 2CV brakes. This car has the best brakes I've ever seen! They are mounted on the transmission instead of at the wheels between the transmission and axles. I don't know if this provides better braking or the calipers have two pistons and the discs are bigger or what.

My Fiat Spider has four wheel power disc brakes and the Citroen puts it to shame when it comes to braking. The Fiat Spider, the braking power is so [censored] poor, you can't lock the brakes up at all. Well not on dry pavement anyway. That was Fiat's version of anti-lock braking!

 

[slacktide_bitog]

Isn't Pentosin CHF the same or very close? You can probably use it in your 2CV. The parts stores carry it. Walmart has Prestone European power steering fluid, which is like the CHF and most likely ok to use as well.

 

[spackard]

> Speaking of Citroen 2CV brakes. This car has the best brakes I've ever seen! They are mounted on the transmission instead of at the wheels between the transmission and axles. I don't know if this provides better braking or the calipers have two pistons and the discs are bigger or what.

Those are inboard brakes, as opposed to outboard brakes.
You reduce the unsprung weight at the wheel, so that's good.
Cooling isn't as good, I believe. But you don't have much car to brake.
They're harder to maintain, and a pain in the rear if you ever have any rust in the bore.

Not absorbing water was deemed to not be that awesome of a brake design.
Hygroscopic fluid slowly lowers boiling temp as it absorbs water.
The other kind still gets water into the system, but the water boils at
water temp, so if the water gets into the hot part of the system
it'll cut out your brakes at a much lower temp than hygroscopic system will.

My dad owned a '67 DS21.

 

[andyd]

For a very brief time I had a DS19. It was 30 yrs ahead of 50's American cars. Michelin radials inboard disc brakes, plastic brake lines.

 

[Jetronic]

LHM doesn't suffer a lower boiling point with water dispersed in it

 

[Yah-Tah-Hey]

American Graffiti

 

[Trav]

When I had my SM and CX Pallas I remember seeing these new at the dealer, it was in 1985 IIRC the models were 2CV Charleston, Duck and Dolly. Pretty cool cars.
I owned a Citroen GS with a flat 4 air cooled, it was a good car and fun to drive.

 

[Popsy]

If you look into the history of the Citroën DS, you'll see Citroën made the move from somewhat modified/adapted brake fluid (LMS and LHS2, which you could temporarily replace with DOT3 + castor oil) in the earlier DS, to LHM (from 1966 to 2000) in all cars with hydraulic suspension.
All hydraulic parts were painted green (earlier with LHS were painted red I think) to avoid confusion...and leaks, since both fluids were totally incompatible.
-
All that to say, yes, LHM is mineral (Liquide Hydraulique Mineral). Not certain at all, but it seems you can use the red MIL-H-5606 fluid, like Aeroshell 41, that is compatible with green gaskets.

DOT3/4 brake fluid will more than probably cause leaks if the gaskets are original "green" gaskets.

Maybe you can get some Total LHM+ fluid?

http://www.micksgarage.com/proddetails.aspx?pid=1209568

It is quite cheap here in Frogland, for sure...I've grown up with plenty of green bottles in every supermarket and service station

Edit : GS and CX were the last "real" Citroën with Citroën engines, before the PSA merge. Off topic but I think the Citroën 2500cm3 turbo diesel was the best French diesel of its era

The flat four were fun, remember the GSA X3 when I was young.

 

[fdcg27]

The 2CV is a neat car and is a worthwhile addition to any collection of European cars not typically seen in this country.
Does the Citroen really have vastly better brakes than the Fiat, or is it just that the little twin can't gather enough speed that it really matters? Fiats typically have very good brakes, so if those on your car are really weak, I'd wonder about what might be wrong with the system.
Is your turbo late 124 the OEM one? IIRC, the turbo installation wasn't factory but was done here by a third party, maybe Legend Industries?

 

[Trav]

The CX had the most comfortable seats and ride of any car I drove. That is truly one car I miss probably more than any other, such a solid well built car.
I had it for years and it never had a problem, it was a joy to own and drive. The SM was good but very finicky.

 

[TurboFiat124]

Originally Posted By: fdcg27
The 2CV is a neat car and is a worthwhile addition to any collection of European cars not typically seen in this country.
Does the Citroen really have vastly better brakes than the Fiat, or is it just that the little twin can't gather enough speed that it really matters? Fiats typically have very good brakes, so if those on your car are really weak, I'd wonder about what might be wrong with the system.
Is your turbo late 124 the OEM one? IIRC, the turbo installation wasn't factory but was done here by a third party, maybe Legend Industries?


The 2CV has 29 BHP, my Fiat Spider has 155 BHP with the turbo.

Mine is not a Legend industries system. Mine uses a PBS manifold and a T3 from a Volvo 240.

It's not just me but most people complain that the brakes are not that great on Fiats. There was a friend who designed a front braking system called WHOA! brakes. He passed away but sold the design to one of the parts suppliers. It uses a larger rotor, larger master cylinder and two piston calipers. I road in his car and the brakes was impressive.

http://www.midwest124.com/whoa_brakes.htm

Here are some photos of my Spider:

http://s222.photobucket.com/user/turbofiat/library/1980 Spider?sort=6&page=1

http://s222.photobucket.com/user/turbofiat/library/Garrett T3?sort=2&page=1

http://s222.photobucket.com/user/turbofiat/library/GM 5 PIN HEI module?sort=6&page=1

 

[Popsy]

Citroën traditionally had "brutal" brakes, where you just have to lay your feet on the pedal (we called it mushroom here) to brake normally. Don't know if it's the same on these late 2CV? It gave an impression of very powerful braking.

I can't complain on the braking of my two Fiat, even the Marea with rear drums...but this one is slow and don't really need powerful brakes!

PS: really nice rides

 

[Jetronic]

The mushroom wasn't used in all cars, or even all engine options of the cars. I believe the DS wth injection engines used the mushroom.

But overservo'ed brakes is pretty common in Citroens, though I don't remember that being an issue in my AX.

 

[Ben Boyle]

I'll resurrect this thread because I also own an 80s 2CV. I assume you probably got your LHM from Kenji at French Parts Service. This fluid can be had from Napa and Auto Value stores https://www.napaonline.com/napa/en/p/AOR1402106_0423208778

I have seen late 2CVs that people have put DOT fluid into and it dissolves the seals and causes a disaster.

BTW: IS your car a real Charleston? Most of the clone don't bother with the badges but your car has bench seats.