ZF 4HP22

Transmission general data

The 4-speed automatic transmission ZF 4HP22 was designed in the early 1980s for 2-3 liter diesel (rear-driven) car models. It has a "classic" engineering structure, ensuring not only high robustness, but also even wear-out of parts without obvious soft spots. The 4HP22 - 24 unit was used by all European automakers of high-priced and reliable cars: Audi, BMW, Jaguar etc. In terms of design, this transmission is similar to famous A4LD from Ford and A40-series from Toyota. The 4HP24 unit found application in 4WD models.

Technical issues and repair guidelines

The difference between 4HP22 and 4HP24 modifications lies in frictions and steel discs in packages. The modification with the valve body (type Е9) and 4 solenoids is the most common in repair, while earlier series with 5-solenoids in the valve body are considered to be a rarity.The ZF 4HP24 unit is a fail-safe and massive transmission, constructed with the help of high-quality materials, ensuring enhanced safety margin.

Repair procedures

Friction components of the Forward package are the first to get burnt because of intensive operation. The percentage of hard parts replacement and seals (separately) is quite low only in the overhaul kit (repair kit). It is common to replace worn-out pump housing bushing (covers – 17 mm), and less frequently bushings (13 mm) with the pump gasket and pump seal in the 4HP22/24 unit suffering from oil starvation. Land Rover’s oil pump gets out of service early because of contaminated fluid and long-term operation with a faulty torque converter. It is required to perform the torque converter repair together with the abovementioned procedure.The improper operation of clogged or worn-out solenoids and valve body is named as the main reason of oil starvation causing burning of the package Forward.

The replacement of solenoids is a scheduled procedure for old cars using this transmission. The problem of a dirty valve body is usually explained by worn-out locking clutch of the torque converter. If there are some delays with gears shifting, kicks or slippage in ZF 4HP22 with mileages above 200 thousand kilometers, then it signals that springs and solenoids cannot handle the dirt from frictions falling on valves. The minor overhaul prolongs the resource of this transmission for many years. It is suggested that the average resource of ZF4HP22 (4HP24) before the overhaul can reach up to 300 thousand kilometers, but it depends on the driving style “aggressiveness”.