up without destroying the transmission
back up uphill or start very fast backing up! 2CV's with disc brakes
have a severe problem: While backing up with a high tourque, the
collar for the center shifting fork twists off the gear assembly (see
The reason is that this collar was not tightened enough during
production. Afterwards it is almost impossible to tighten it more.
This requires disassembling the transmission. When you back up very
hard you put a high load on the transmission, which leads to friction
between the shifting fork and the collar.
The gear assembly warps and the collar twists off the thread. The
collar is peened in a few spots, but this cannot stand the force. Once
the collar is twisted off completely the gear assembly will pull
apart. Mostly this leaves the transmission in permanent 3rd gear.
The synchro-ring twists and the gears cannot engage anymore. Maybe
you can manage to engage another gear - a transmission with two gears
engaged simultaneously - will lock up. To press the clutch won't help
because it is not the motor that blocks!
A repair is challenging. In most cases the transmission will need to
be replaced. This is the reason why it is so hard to find a good used
transmission with disc brakes.
So be gentle in reverse, try to avoid a high tourque. Typical
situations where the transmission is threatened are steep downhill
driveways to your garage or house. If there isn't enough space at the
bottom to turn around on a level surface, go down in reverse. This way
you have the high tourque coming back up in 1st gear, where it doesn't
harm the transmission. Also it makes it easier to leave the driveway
pulling out foreward.
Also don't fall for the urban legend that "if you can't make it
up a hill in 1st gear, turn around and go in reverse". This was
true in the old 2CVs with 12 or 16 HP engines. In the later model 2CVs
with a 602cc motor, the gear ratio for 1st and reverse gear is
Another typical situation where we saw many transmissions damaged was
with plenty of snow in winter. The 2CV got stuck in snow, the usual
response would be to go in reverse to get back out of the mess.
Usually one wheel has less traction, so this wheel will just be
spinning. The other wheel is standing still. The spinning tire rubs on
the snow and ice surface. The friction creates heat and melts the ice
away. Once the tire hits the bare pavement under the snow, it suddenly
has good traction. This gives the transmission a very high tourque
impuls, quite often enough to pull the collar off the shaft.
The best way to keep this problem from happening is to be aware of
the situations that will cause it, and simply avoid these situations.
your transmission well
years now, the production of transmissions has been discontinued.
Spare parts are limited to a few bearings, which makes it hard to
rebuild a transmission. The only way is to salvage core returns, which
mostly show the same problem as your dead transmission. So finding
good parts from returned transmissions is getting harder with the
higher mileage these boxes have seen. Already, the ratio is about 50%,
meaning, that it takes approximately two transmissions to salvage, to
gain one good unit. So treat your transmission well and don't throw it
away when it is defective. Parts of it might help keeping another 2CV
going in the future!
you could do to extend the lifetime of your transmission
the oil regularly after about 15000 km
The transmission needs 80W90 Hypoid oil. The code is GL4 - GL5 is not
recommended if GL4 is obtainable. Don't use synthetic oil. This has
caused problems in the past. Just stick with conventional mineral oil
of the right weight and very important, the oil must be for "hypoid"
transmissions and differentials (GL4). In many vehicles, the
transmission and the differential are separate units. The pressure
between the gears in a regular transmission without a differential
built in is not too high. So regular gear oil will do the job here. In
the differential however, the pressure between the gears is extremely
high. In regular gear-oil, the molecules would just break apart under
his pressure. This is why the oil for the differential is of a higher
In the 2CV transmission, the differential is integrated. Both sides
in the box, gears and differential share the same oil. So make sure
that you use the right oil.
Change the transmission oil with every second oil change for the
engine. Drive the car to get the oil up to temperature and drain
engine oil and transmission fluid together. To drain the transmission
fluid, just remove the drain plug on the underside. Allow it plenty of
time to drain. Check the drain plug magnet for metal particles. Don't
be shocked, there will always be some metal powder sticking to the
magnet in the plug. The "cap" on the drain plug may get up
to half an inch high. If it is more, or solid parts, like chipped off
parts of gear teeth, it is highly recommended to have the transmission
inspected and rebuilt.
To refill the oil, put the cleaned drain plug back in and pull it
tight. Then open the plug on the passenger side of the transmission.
Now fill a quart of transmission fluid trough the hole. There is no
dipstick to measure the oil level. Once the oil starts running out the
side hole, the filling process is finished. Put the plug back in and
shift too rapidly
For shifting, both shafts have to turn at the same speed before the
gears can be engaged. This is the job of the synchro-rings. When you
shift gears, you will feel a little resistance in the shifting lever,
just before the gears engage. This is the synchro-ring, retarding or
accelerating the other shaft to the same speed. Once the speed is
equal, the gears engage. This synchronization process causes wear on
You can control the wear by the way you shift gears. A very sportive,
fast gear jamming way of engaging gears, leads to a high wear on the
synchro-rings. Once the synchro-rings are worn, this is it. They
cannot be replaced, and chances are that parts from other salvaged
transmissions show the same wear. So subsequently, the transmission is
To prevent this, watch the way you shift gears. Don't force the gears
in rapidly; applying gentle pressure, give the synchro-ring some time
to synchronize the speeds. This way you can significantly minimize the
wear on the synchro-rings.