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transmission for Alle 2CV6

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Gearbox in the exchange. Suitable for Citroen 2CV6 for disc brake. 250 euros Old part deposit

t. Note: It is not oil on the gearbox, please fill it up! (Article number 20000)

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Oil drain screw magnetically, suitable for Citroen 2CV, HY, DS, 11CV (with oil pan out of sheet

metal). Interior square. The suitable tool has our number 20221. Or. No. A1321M, thread M16x1,5x20

Oil drain screw (engine + gearbox) suitable for Citroen 2CV, DS, HY, GS. Thread M16.

2CV6, speedometer pinion in gearbox. 16 theeth! The pinion has an outside diameter of 20,7mm, the

shank has a diameter of 8mm.

Motor-gearbox screw connection: Short stud bolts (these are the lower stud bolts) between the motor

and gearbox. Suitable for Citroën 2CV6 + 2CV4, Dyanne AMI8, Mehari

Motor-gearbox screw connection: long stud bolts (these are the upper stud bolts, as they also hold

the air filter holder) between the motor and gearbox. Suitable for Citroën 2CV6 + 2CV4, Dyane, AK, Ami8

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The transmission of the Citroën 2CV6 is one of the vehicle’s most important components. It affects shifting behavior, torque, engine speed, ride comfort, and the appropriate braking system. Since many Citroën A-series models are technically related, transmissions have frequently been swapped between 2CV, Dyane, Ami, Méhari, Acadiane, and AK models over the years. Therefore, a transmission should not be judged solely on its external appearance.

Particularly crucial factors are the gear ratio, the type of front brake system, the brake fluid used, and the technical condition of the transmission. Proper use of reverse gear also plays an important role, as incorrect operation or excessive strain can cause damage inside the transmission.

Citroën 2CV6 Transmission: Differences, Gear Ratios, and Braking System

Design and shifting characteristics of the 2CV6 transmission

The 2CV transmission is a 4-speed transmission with reverse gear. Second, third, and fourth gears are synchronized, whereas first gear is not.

This means: First gear should only be engaged when the vehicle is stationary. If it is engaged while driving or coasting, significant shifting noises may occur. This is not necessarily a defect, but rather a design feature of this transmission type.

If first gear is difficult to engage while the vehicle is stationary, it may help to briefly shift into second gear first and then into first gear. This often allows the gears to align better.

2CV6 Transmission and Gear Ratio: 8/33 or 8/31?

Various gear ratios were used in the Citroën A-series models. For the 2CV6, the 8/33 ratio is typical in many cases. This ratio is considered rather short and suits the 602-cc engine well.

A short gear ratio ensures good low-end torque, good hill-climbing ability, and lively handling. At higher cruising speeds, however, the engine RPM is slightly higher.

Other models such as the Dyane 6, Ami 8, or Acadiane were often equipped with longer gear ratios such as 8/31. These transmissions can make the vehicle feel smoother at higher speeds but reduce torque, especially on inclines or when loaded.

Model / Transmission Type Typical gear ratio Character Effect in practice
2CV6 often 8/33 rather short Good torque, good hill-climbing ability, higher RPM
Dyane 6 / Ami 8 / Acadiane often 8/31 longer lower RPM, less torque
AK / Méhari / Commercial vehicle variants Varies by model load-dependent Depends on usage and year of manufacture

For a 2CV6 that is as close to the original as possible, an 8/33 transmission is generally the better choice. A longer-ratio transmission can be more comfortable for frequent highway driving, but it alters the vehicle’s character.

Drum brake gearboxes and disc brake gearboxes on the 2CV

A very important difference lies in the braking system. For the Citroën 2CV6, there are transmissions for internal drum brakes and transmissions for internal disc brakes.

These two versions differ not only in their brake components but also in the fluid system used.

Drum brake transmission

Earlier 2CV6 models up to the 1981 model year have internal front drum brakes on the transmission. These vehicles use classic DOT or Lockheed brake fluid.

Typical features:

Feature Drum brake transmission
Front wheel brake Internal drums on the transmission
Brake fluid DOT / Lockheed
Handbrake acts on the front brake drums
Transmission housing without mounting for disc brake calipers
Conversion only practical with further modifications

Disc brake transmission

Later 2CV6 models from 1981 onward feature front disc brakes mounted inside the transmission housing. These vehicles use LHM, i.e., green mineral-based Citroën hydraulic fluid.

Typical features:

Feature Disc brake transmission
Front wheel brake Internal disc brakes on the transmission
Brake fluid LHM, green, mineral-based
Handbrake Separate handbrake pads on the disc brake
Transmission housing with mounting for brake calipers
Hoses and seals must be compatible with hydraulic brake fluid

Important: Hydraulic brake fluid (LHM) and DOT/Lockheed brake fluid must never be mixed. The seals and components of the respective systems are designed differently. Mixing them can cause severe damage, up to and including total failure of the brake system.

Can drum and disc brake systems be easily swapped?

A direct swap is not recommended. While many mechanical components are interchangeable among Citroën A-series models, the brake system, handbrake, lines, master cylinder, and wheel cylinders must all be compatible with one another.

If a disc brake system is installed in an older vehicle with a drum brake system, simply swapping out the brake system is usually not enough. In that case, the entire brake system must be compatible with the hydraulic-mechanical (LHM) system.

Conversely, installing a drum brake assembly in a vehicle with a hydraulic disc brake system is also not advisable unless the entire brake system is adapted accordingly.

The following points should be checked before a conversion:

Checkpoint Why is this important?
Front brake system Drum or disc
Brake fluid DOT/Lockheed or LHM
Master cylinder Must be compatible with the fluid system
Handbrake cables vary depending on the brake system
Brake lines and seals must be compatible with the material
Drive shafts and flanges Check depending on the year of manufacture
Speedometer cable drive may vary depending on the gear ratio
Clutch design Depends on model year and engine

Citroën 2CV6 Transmission: Reverse Gear, Weak Points, and Inspection

Reverse gear on the 2CV: Intended only for maneuvering

The reverse gear in the 2CV transmission is intended for short maneuvering movements. Prolonged driving in reverse, high RPMs, or heavy loads in reverse should be avoided.

A specific problem is known to occur in Citroën A-series models: After prolonged or forceful driving in reverse, the transmission may lock up. The cause is usually not directly related to reverse gear itself, but rather to a component inside the transmission.

The area around the sliding sleeve for 2nd and 3rd gears is frequently affected. A lock nut or threaded bushing is located there. If this bushing loosens, the sliding body can shift too far. This can cause the shifting components to jam. The transmission then behaves as if two gears were engaged at the same time.

Why can the transmission lock up after driving in reverse?

When driving in reverse, different forces act on the transmission than during normal forward driving. Reverse gear is not designed for long distances, high speeds, or strong acceleration.

If you drive in reverse with the throttle wide open or under heavy load, unfavorable forces can be transmitted to the shift mechanism. If a retaining clip is already weakened or no longer properly secured, a bushing may come loose. After that, the sliding sleeve may shift out of its intended position.

Drive in reverse only slowly, for short distances, and without heavy loads.

This is especially important on long driveway approaches, garage entrances, inclines, when towing a trailer, or when driving on grass or gravel. Unfortunately, this is a real weak point of the transmission.

Typical signs of a seized 2CV transmission

The following symptoms may indicate a blockage or damage to the shift mechanism:

Symptom Possible meaning
A metallic noise suddenly occurs after driving in reverse A safety device or shift component may have come loose
The vehicle will no longer move The transmission may be internally locked
The clutch is engaging, but the drive is blocked The problem is likely in the transmission
The shift lever feels unusual Shift forks or shift sleeves may be misaligned
The transmission feels as if two gears are engaged Shift components may be jammed

In this case, do not force the gearshift or attempt to drive off. Also, do not use the starter motor to “free up” the vehicle. This can cause additional damage to gears, shift sleeves, or shift forks.

What to do if the 2CV transmission locks up?

If the transmission locks up after driving in reverse, the vehicle should be secured immediately and not moved any further.

Recommended procedure:

  1. Secure the vehicle to prevent it from rolling away.
  2. Do not continue to shift gears or drive off by force.
  3. Remove the upper transmission cover.
  4. Check the position of the shift sleeves and shift forks.
  5. Position the loosened lock nut correctly and secure it.
  6. Check the transmission oil for metal particles.
  7. Replace the transmission oil if necessary.
  8. Carefully check all gears before a test drive.

With a bit of luck, the inspection and repair can be performed through the upper transmission cover. This depends on whether secondary damage has already occurred.

When does the transmission need to be removed?

Not all damage can be repaired through the transmission cover. Removal and complete disassembly are recommended if there is significant wear or damage.

Findings Recommendation
Retaining bushing severely damaged or loose Disassemble and inspect the transmission
Teeth damaged or broken Complete technical inspection required
Sliding sleeve damaged Replace component
Shift fork bent Inspect or replace shift fork
Metal particles in the oil Clean and inspect the transmission
Squealing noises after repair Inspect bearings, bevel gear, and ring gear

A loose lock nut should not simply be tightened back on. It must be permanently secured. Depending on its condition, options include clean caulking, suitable threadlocker, or, in special cases, a professional mechanical lock.

Typical weak points of the 2CV6 transmission

In addition to the described problem with reverse gear, there are other typical wear points.

Wear on synchronizer rings

A grinding or sticking sensation when shifting, especially between 2nd and 3rd gear or when downshifting from 3rd to 2nd gear, often indicates worn synchronizer rings.

Possible causes:

Cause Description
Worn synchronizer rings Common cause of shifting noises
Worn shift sleeve Gear does not engage properly
Worn guides Imprecise shifting feel
Old or incorrect transmission fluid Poor shifting performance

Often, the wrong type of modern transmission fluid is the cause

In many cases, the cause is not serious transmission damage, but rather unsuitable modern transmission oil. Switching to a suitable mineral GL-4 transmission oil often results in noticeably improved shifting performance.

Bearing noises

Howling, humming, or grinding noises should be taken seriously.

Noise Possible cause
Howling under load Bevel gear, ring gear, or bearing
Rattling at idle Input bearing, primary shaft, or clutch area
Roaring in all gears Main bearing or differential bearing
Noise only in one gear Gear pair or gear bearing

Leaks

Leaks are common in older transmissions.

Location Possible cause
Output flanges Hardened oil seals or worn-in running surfaces
Shift cover Old gasket
Speedometer cable drive Defective sealing ring
Drain and fill plug Old sealing rings
Case seam Inadequate sealing following a previous repair

Transmission fluid for the 2CV6 transmission

The 2CV transmission typically requires about 0.9 liters of transmission oil. The correct fill level is reached when oil leaks out of the side inspection port.

Recommendation for normal road use:

Point Recommendation
Quantity approx. 0.9 liters
Viscosity SAE 75W80
Specification Mineral GL-4 gear oil
Filling level until oil leaks from the inspection port
Not recommended Engine oil, ATF, or very thin low-viscosity oils

A mineral 75W80 GL-4 transmission oil is a sensible choice for classic transmissions. If the history is unknown, the oil should be changed and checked for metal abrasion, water, or a strong odor.

Properly inspecting the 2CV transmission

Before installation, purchase, or repair, the transmission should be thoroughly inspected.

Important checkpoints:

  1. Is it a drum brake or disc brake transmission?
  2. Is DOT/Lockheed or LHM used?
  3. What gear ratio is installed?
  4. Is the transmission compatible with the engine and intended use?
  5. Are there any shifting problems or noises?
  6. Are there any visible leaks?
  7. Is the correct transmission fluid used?
  8. Has the vehicle been modified in any way?

Especially with older vehicles, the original transmission is not always present. Transmissions from the Dyane, Ami, Méhari, Acadiane, or commercial vehicle variants may be mechanically compatible but can differ in gear ratios, braking systems, and other details.

FAQ on the Citroën 2CV6 Transmission

Which transmission is original on the 2CV6?

An 8/33 transmission is typical for many 2CV6 models. This gear ratio works well with the 602-cc engine and provides good low-end torque.

Can a Dyane or Ami transmission be used in the 2CV6?

Mechanically, many parts may fit. However, the gear ratio, brake system, clutch, speedometer cable drive, and drive shafts must be checked. A longer gearbox also changes the driving characteristics.

Which is better: 8/33 or 8/31?

For a classic 2CV6, 8/33 is usually a better fit and comes standard. 8/31 has a longer gear ratio and can feel smoother at higher speeds, but offers less torque.

Can LHM be mixed with DOT brake fluid?

No. LHM and DOT/Lockheed brake fluid must never be mixed. Doing so can cause serious damage to the brake system.

Why does 1st gear make a clunking noise when engaged?

First gear is not synchronized in the 2CV transmission. It should only be engaged when the vehicle is stationary.

Why can the transmission lock up after driving in reverse?

During prolonged or heavy-duty reverse driving, a lock nut in the area of the sliding sleeve may come loose. This can cause shifting components to jam and the transmission to lock up.

How should reverse gear be used?

Reverse gear should only be used slowly, briefly, and without heavy loads. It is intended for maneuvering, not for long distances.

What should be done if the transmission locks up?

The vehicle should not be moved any further. Do not force the gearshift or attempt to drive off. A technical inspection via the upper transmission cover is the first sensible step.

Summary

The 2CV6 transmission is robust but requires proper configuration and careful handling. The right gear ratio, the correct braking system, the proper fluid system, and good mechanical condition are crucial.

For an original 2CV6, an 8/33 transmission is the right choice. For disc brake transmissions, the LHM system must be used; for drum brake transmissions, the DOT/Lockheed system. The two brake systems must not be mixed.

Reverse gear should only be used for slow maneuvering. In the worst-case scenario, prolonged or heavy-duty reverse driving can cause components in the shift mechanism to come loose and the transmission to lock up.

Every transmission should be thoroughly inspected before installation, conversion, or repair. This helps prevent mispurchases, consequential damage, and issues with the braking system or gear ratio.