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transmission for Citroën 2CV AMI6-8

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

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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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Citroën Ami 6 and Ami 8 Transmissions: Differences, Gear Ratios, Braking System, and Important Notes

The transmission of the Citroën Ami 6 and Ami 8 belongs to the technical family of Citroën A-series models. This includes, among others, the 2CV, Dyane, Méhari, Acadiane, and the 2CV-based van models. Many components function similarly, and some transmissions can be mechanically interchanged. Nevertheless, there are important differences in gear ratios, braking systems, clutches, drive shafts, speedometer cable drives, and model years.

Accurate identification is particularly important for the Ami 6 and Ami 8. Both vehicles are heavier and more comfort-oriented than a 2CV. For this reason, the transmission was tuned more toward smoother driving, higher cruising speeds, and the respective engine power. A transmission that works well in a 2CV is therefore not automatically the best choice for an Ami.

Citroën Ami 6 and Ami 8 within the A-series

The Citroën Ami 6 and the later Ami 8 are technically based on the A-model family but are designed more independently than a 2CV. They have a heavier body, different comfort requirements, and, depending on the model, a different transmission calibration.

Model Technical Classification Note on the transmission
Ami 6 Early, more comfortable A-model with a 602-cc engine Check that the transmission is suitable for the vehicle's weight and engine power
Ami 8 Further-developed Ami with 602-cc engine Often longer and tuned for touring
Ami Super A distinct model with a different drivetrain concept not to be confused with the standard Ami 6/Ami 8 transmission
2CV6 Lighter vehicle with a 602-cc engine Generally shorter gear ratios and more torque-oriented
Dyane 6 Technically related; tuning similar depending on the model Check gear ratios and braking system

Important: The Ami Super must be considered separately. Although it belongs to the Ami family, it uses a different technical concept and should not be confused with the standard Ami 6 or Ami 8.

Basic design of the Citroën Ami 6 and Ami 8 transmission

The transmission of the Ami 6 and Ami 8 is a 4-speed transmission with reverse. As with the other A models, 2nd, 3rd, and 4th gears are synchronized. 1st gear is not synchronized.

This means: 1st gear should only be engaged when the vehicle is stationary. If 1st gear is engaged while driving or coasting, significant shifting noises may occur. This is due to the design and is not necessarily an indication of a defect.

If 1st gear is difficult to engage while the vehicle is stationary, a simple procedure can help: first shift briefly into 2nd gear and then into 1st gear. This allows the gears to align better.

Citroën Ami 6 Transmission: Special Features

The Ami 6 is heavier and more comfort-oriented than a 2CV. As a result, the transmission must be designed not only for the 602-cc engine but also for the vehicle’s higher weight. In early Ami 6 models, technical details may vary depending on the year of manufacture.

An Ami 6 transmission should always be evaluated in conjunction with the engine, brake system, and year of manufacture. Especially in vehicles that have been used and repaired over decades, the original transmission is not always present.

Typical inspection points for the Ami 6:

Area Meaning
Engine Must match the transmission ratio
Model year Note technical changes
Brake system Check drum or disc brakes
Clutch The type must match the transmission
Drive shafts Check flanges and design
Gear ratio Affects torque and RPM
Speed sensor cable drive may vary depending on the transmission

Citroën Ami 8 Transmission: Special Features

The Ami 8 is an evolution of the Ami 6 and was designed with greater emphasis on everyday practicality and a more comfortable driving experience. The Ami 8 often uses a longer gear ratio than the 2CV6. As a result, the vehicle runs more smoothly at higher speeds but also requires sufficient engine power.

A transmission with too long a gear ratio can make the Ami 8 feel sluggish on hills or when loaded. A shorter gear ratio improves acceleration but increases the engine speed on country roads.

Typical inspection points for the Ami 8:

Area Meaning
Gear ratio often longer and more travel-oriented
Brake system Check carefully depending on the model year
Brake fluid Do not mix DOT/Lockheed or LHM
Clutch Must be compatible with the model year
Driving characteristics A longer gear ratio results in smoother operation but less power
Modifications Many vehicles have been technically modified

Gear ratio for the Ami 6 and Ami 8: 8/31 or 8/33?

An important difference between the transmissions of the A-models lies in the final drive ratio. The 2CV6 transmission often features a 8/33 ratio. This is considered rather short and provides good low-end torque.

In the Ami 6 and Ami 8, depending on the model, longer gear ratios such as 8/31 are more common. A longer gear ratio reduces engine speed at the same speed and better suits the Ami’s comfort-oriented character. At the same time, the vehicle loses some low-end torque, especially on inclines.

Transmission Type / Model Typical gear ratio Character Effect in practice
2CV6 often 8/33 rather short Good acceleration, higher RPM
Dyane 6 often 8/31 or model-dependent tends to be longer smoother at speed
Ami 6 depending on model and year of manufacture Tuned to weight and engine More balanced character
Ami 8 often tuned for longer distances tuned for touring lower RPM, less responsive on hills
Acadiane often tuned for specific usage Designed for commercial vehicle operation Depends on load and application

For the Ami 6 and Ami 8, a longer gear ratio is often suitable if the vehicle is driven primarily on country roads or at a steady speed. On hilly routes or with a heavily loaded vehicle, a shorter gear ratio may be more comfortable.

Can a 2CV6 transmission be installed in an Ami 6 or Ami 8?

A 2CV6 transmission may function similarly mechanically or be installable in certain cases. Nevertheless, it is not automatically the right choice for an Ami 6 or Ami 8.

A 2CV6 transmission often has a shorter gear ratio. This allows an Ami to accelerate better, but the engine speed increases at higher speeds. This can lead to more noise, higher fuel consumption, and a less comfortable ride.

Before converting, the following points should be checked:

Checkpoint Why is this important?
Gear ratio affects torque, RPM, and ride comfort
Brake system Drums or discs must be compatible
Brake fluid Do not mix DOT/Lockheed or LHM
Clutch Note the model and year of manufacture
Drive shafts Check flanges and model
Speed sensor shaft drive May vary depending on the gear ratio
Handbrake varies depending on the brake system
Vehicle weight The Ami is heavier than the 2CV
Authenticity Not every compatible transmission is close to stock

For the most authentic setup possible, a transmission that fits the Ami is usually the better choice.

Can a Dyane, Acadiane, or Fourgonnette transmission fit in an Ami?

Transmissions from Dyane, Acadiane, or Fourgonnette models belong to the same technical family. However, they differ in gear ratios and design depending on the model.

A transmission tuned similarly to a Dyane or Ami 8 may be suitable for comfort-oriented driving. A commercial vehicle transmission from an AK, AKS, or Acadiane, on the other hand, may be tuned differently, particularly with regard to load capacity and intended use.

Before installation, you must always check whether the transmission is compatible with the vehicle. Gear ratios, the braking system, the clutch, the drive shafts, and the speedometer cable drive are particularly important.

Drum Brake Transmissions on the Ami 6 and Ami 8

Earlier A-model versions feature front drum brakes mounted inside the transmission housing. These vehicles use conventional brake fluid based on DOT or Lockheed specifications.

Typical features:

Feature Drum brake transmission
Front wheel brake Internal drums on the transmission
Brake fluid DOT / Lockheed
Handbrake acts on the front drums
Transmission housing without mounting for disc brake calipers
Application typical for older models

On an Ami with a drum brake system, a disc brake gearbox should not be installed without first inspecting and adjusting the entire brake system accordingly.

Disc brake transmission on the Ami 8

Later A-model versions may be equipped with internal disc brakes. These vehicles use LHM, i.e., green mineral hydraulic fluid.

Typical features:

Feature Disc brake mechanism
Front-wheel brake Internal brake discs on the transmission
Brake fluid LHM, green, mineral-based
Hand brake Separate handbrake pads on the disc brake
Transmission housing with mounting for brake calipers
Seals and lines must be suitable for LHM

Important: Hydraulic brake fluid (LHM) and DOT/Lockheed brake fluid must never be mixed. Seals, boots, and lines are designed for different fluids. Mixing them can cause serious damage to the brake system.

Conversion from drum brakes to disc brakes on American cars

Converting from drum brakes to disc brakes is not a simple gear change. It affects the entire braking system.

The following, among other things, must be checked or adjusted:

Area Checkpoint
Transmission housing Is there a mounting for a disc brake system?
Brake calipers compatible with the system?
Handbrake mechanism Different design for disc brakes
Master cylinder Compatible with LHM or DOT?
Brake lines Compatible materials?
Rear wheel brake cylinders Compatible with the fluid system?
Brake fluid reservoir Clearly labeled?
Seals Suitable for the fluid used?

A mixed system consisting of DOT/Lockheed components and LHM components should be avoided at all costs.

Reverse gear on the Ami 6 and Ami 8: use only briefly and slowly

Reverse gear on the Ami 6 and Ami 8 is intended for maneuvering. Prolonged reverse driving, high RPMs, or heavy loads should be avoided.

It is known that A-model transmissions can seize up after prolonged or forceful reverse driving. The cause is usually not directly related to reverse gear itself, but rather to a component in the area of the sliding sleeve for 2nd and 3rd gears.

There is a retaining or threaded bushing located there. If this bushing comes loose, the sliding body can shift too far. This can cause shifting components in the transmission to jam. The transmission then behaves as if two gears were engaged at the same time.

Why can the American transmission lock up after driving in reverse?

When driving in reverse, different forces act on the transmission than during normal forward driving. If you drive in reverse for a long time, with a lot of throttle, or under heavy load, unfavorable stresses are placed on the shift mechanism.

In the case of the American car, the vehicle’s higher weight compared to a 2CV is an additional factor. As a result, higher forces can act on the clutch and transmission when maneuvering, especially on inclines or uneven surfaces.

The simple rule is:

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

The following should be avoided in particular:

  • longer reverse trips across driveways or garage entrances
  • Reversing at high RPM
  • Heavy acceleration in reverse
  • Reversing on inclines
  • Forcibly maneuvering the vehicle when it is stuck
  • Rocking the vehicle back and forth between forward and reverse gears

Typical signs of a seized automatic transmission

The following symptoms may indicate a lockup or damage to the transmission:

Symptom Possible meaning
A metallic noise occurs after driving in reverse A safety device or shift component may have come loose
The vehicle will not move The transmission may be internally locked
The clutch engages, but the drive remains locked Probable transmission failure
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
The wheels lock up when starting Possible internal transmission lockup

In this situation, do not force the shift, start moving, or use the starter. Doing so can cause further damage to gears, shift sleeves, or shift forks.

What to do if the automatic 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 shift gears or drive off.
  3. Do not force the shift lever.
  4. Do not use the engine or starter to release the lockup.
  5. Have the upper transmission cover inspected.
  6. Check the position of the shift sleeves and shift forks.
  7. Position the loose retaining bushing correctly and secure it.
  8. Check the transmission fluid for metal particles.
  9. Carefully check all gears before taking a test drive.

With a bit of luck, the cause can be identified and fixed by inspecting the upper transmission cover. Whether that is sufficient depends on whether secondary damage has already occurred.

When does an American transmission need to be removed?

Removal and complete disassembly are recommended if significant damage is visible or if the transmission continues to exhibit issues after the initial inspection.

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 Check bearings, bevel gear, and ring gear
Gear pops out Check the shift sleeve, detent, and bearings

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

Typical weak points in the Ami 6 and Ami 8 transmissions

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

Shifting problems and synchronizer rings

Cracking or sticking 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
Incorrect or old transmission fluid Poor shifting performance
Higher vehicle weight Additional strain on the drivetrain and clutch

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
Loud howling during load changes Wear or incorrect adjustment

Leaks

Leaks are common in older American 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
Collar area Age-related cracks or leaks

Transmission oil for Citroën Ami 6 and Ami 8

Most transmissions in the A-model family typically require about 0.9 liters of transmission fluid. The correct fluid level is reached when oil leaks out of the side check port.

Recommendation for normal road use:

Point Recommendation
Quantity approx. 0.9 liters
Viscosity SAE 75W80
Specification Preferably mineral GL-4 gear oil
Filler level until oil leaks out of the check port
Inspection Check regularly
Not recommended Engine oil, ATF, or very thin low-viscosity oils 

If the history is unknown, the transmission fluid should be changed and checked for metal particles, water, or a burnt smell.

Inspect Ami transmissions before installation or repair

Before installation, purchase, or repair, a transmission for the Ami 6 or Ami 8 should be thoroughly inspected. Many vehicles have been modified over the years or equipped with components from other A-series models.

Important checkpoints:

  1. Is the transmission compatible with the Ami 6 or Ami 8?
  2. What is the gear ratio of the transmission?
  3. Is it a drum brake or disc brake transmission?
  4. Is DOT/Lockheed or LHM used?
  5. Are the clutch, drive shafts, and speedometer cable drive compatible?
  6. Does the parking brake mechanism fit?
  7. Is the transmission compatible with the existing engine?
  8. Are there any shifting problems or noises?
  9. Are there any visible leaks?
  10. Is the correct transmission fluid used?
  11. Has the vehicle already undergone any technical modifications?
  12. Is it possibly an Ami Super, which requires special consideration?

FAQ on Citroën Ami 6 and Ami 8 Transmissions

Which transmission fits in an Ami 6?

That depends on the model year, brake system, engine type, and technical specifications. Key factors include the gear ratio, clutch, drive shafts, speedometer cable drive, and brake system.

Which transmission fits in an Ami 8?

An Ami 8 requires a transmission that matches the engine, brake system, and desired driving characteristics. Longer gear ratios are often advisable, as the Ami 8 is designed with a focus on comfort.

Is a 2CV6 transmission suitable for an Ami 6 or Ami 8?

A 2CV6 transmission may be mechanically similar, but it usually has shorter gear ratios. This improves low-end torque, while engine speed and noise may increase at higher speeds.

Is a Dyane transmission suitable for an Ami?

A Dyane transmission may fit depending on the model, but must be checked carefully. The gear ratios, brake system, clutch, and speedometer cable drive are particularly crucial.

What is the difference between 8/31 and 8/33?

8/31 has a longer gear ratio and reduces engine RPM at the same speed. 8/33 has a shorter gear ratio and improves acceleration. Which gear ratio is better suited depends on the vehicle and its intended use.

Can LHM be mixed with DOT/Lockheed 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 first gear grind in the American car?

First gear is not synchronized. It should only be engaged when the vehicle is stationary. Shifting noises when engaging while the vehicle is rolling are possible due to the design.

Why can the American transmission lock up after driving in reverse?

During prolonged or heavy-load reverse driving, a retaining bushing 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 in the Ami?

Reverse gear should only be used slowly, briefly, and without heavy loads. It is intended for maneuvering, not for extended periods of driving in reverse.

What should be noted regarding the Ami Super?

The Ami Super differs significantly from the Ami 6 and Ami 8 in technical terms. The transmission and drivetrain should therefore not be treated the same as those in the standard Ami 6 or Ami 8 models.

Summary

The transmission for the Citroën Ami 6 and Ami 8 must always be selected to match the vehicle type, engine, braking system, and intended use. Although many transmissions from the A-model family look similar, the gear ratio, braking system, clutch, drive shafts, and speedometer cable drive are crucial.

The Ami 6 and Ami 8 are heavier and more comfort-oriented than a 2CV. Therefore, a suitable gear ratio is particularly important. A longer gear ratio can be more comfortable at cruising speeds, while a shorter gear ratio offers better low-end torque.

DOT/Lockheed brake fluid is used in transmissions with drum brakes. LHM is used in transmissions with disc brakes. The two systems must not be mixed.

Reverse gear on the Ami 6 and Ami 8 should only be used for slow maneuvering. Prolonged or heavy-load reverse driving can cause components in the shift mechanism to loosen and the transmission to lock up.

Every Ami transmission should be carefully inspected before installation, conversion, or repair. This helps prevent mispurchases, consequential damage, and problems with the gear ratio, brake system, or shift mechanism.