The 4HP22EH and 24 EH was used by Landrover in the P38 Range Rover and the Disco 2.

All our boxes are fully rebuilt including the valve body and come complete with a rebuilt torque converter.

Heavy Duty ZF Autoboxes

We are able to supply the ZF4HP22 with optional strength upgrades depending what you are doing with the vehicle, what gearing, what engine Etc.

Stage 1 Upgrade

We can build the 4HP22 but fit the centre section of the box with the bigger 4HP24 internals which upgrades one of the weak links being the C1/C2 one way clutch, the 24 one is much stronger,

another part which gets upgrade is the Planetry Gearset, the solid 24 type being much stronger,

Just the centre internals are changed so the box stays the same externally. This upgrade is an additional £250 on top of the normal rebuilt exchange price of £675 or £725, depending if the box is hydraulic or electronic.

Stage 2 Upgrade

The box can be built with both the 4HP24 internals as above but also the 24 front end as well giving you the added strength of having the larger 24 “A” clutch, also a weak point with larger engines.

There are 2 fitting implications of doing this, the unit is 15mm longer and the oil cooler nipples are M18 x 1.5 thread, on the early 22″s these threads are M16 X 1.5, the later 22″s like the TD5″s are already M18. This upgrade is an additional £500 on top of the normal rebuilt exchange price of £675 or £725, depending if the box is hydraulic or electronic. Note the Stage 2 upgrade can be specified to accept the medium and the large type converter. We are often unable to offer the medium converter option due to availability problems but if you are considering the stage 2 upgrade then you are likely to want the large converter anyway for the reasons below.

Torque Converter Upgrades

The ZF auto as used in the LandRover vehicles uses three different diameters of torque converter. Small. Medium and Large.

“Small” is used on the 300 Tdi, P38 diesel and the TD5. “Medium” is used on the 3.9, 4.0 and the later 4.6 P38. “Large” is used on the early 4.6 P38″s. Note the large converter can only be used with the stage 2 as it will only fit the 4HP24 front end.

A larger converter is desirable on a tuned engine for a few reasons :

1) Lower stall speed, there’s little point in having a nice torquey engine if the converter is not transferring the drive and you are revving straight past it. A larger converter will reduce these revs and allow you to take up drive earlier which results in much more relaxed driving. This is by far the biggest advantage of upgrading the converter. Note these reduced revs are not to be confused with lower gear shift points, these stay the same as they are determined by the autobox ECU programming.

2) Less heat generation because of the lower stall speed and reduced ‘slip’.

3) The converter has a lock up clutch inside and the smaller one struggles to cope with a stock engine, never mind a tuned one. This clutch can slip as you accelerate when it should be staying locked. In a TD5 the stock converter is the small one. If you have a stock engine, stick with the stock converter. If the engine has a mild tune then we would recommend upgrading to the medium diameter one, we have sold quite a lot and get very good feedback.

For the TD5 this option is an additional £560 when ordered with an autobox.

4.6+ V8’s – We would recommend the stage 2 and the large converter with a 4.6 or more.

To fit the large converter you will need the 4.6 boss and flexplate assy to match the bigger converter which we can supply at £175.

2.8 TGV to ZF

We would recommend the stage 2 and the large converter with the 2.8 TGV, When using this setup be sure to order the correct conversion kit to suit the large converter. The part number for this kit from Motor and Diesel Engineering in the UK is Kit ’82E’. See below for additional notes on the 2.8.

TD5 ZF upgrades

If you are converting your TD5 Defender to auto you have a few options, I though it may be useful to give some guidance based on our experience. Stock 90/110, fine with a stock 4HP22 Medium Tuned 90, stock ZF, uprated converter Medium Tuned 110, stage 1 ZF, uprated converter Fully Tuned 90, stage 1 ZF, uprated converter Fully Tuned 110, stage 2 ZF, uprated converter Tuned Challenge 90, stage 2 ZF, uprated converter

2.8 International engine to ZF auto

The easiest way to fit a ZF to the 2.8 is to treat it as a 300 Tdi and fit the corresponding autobox from the 300 Disco but as this has the smaller diameter torque converter I would not recommend this set up. For the strongest set up I would suggest purchasing the 2.8 adapter kit made to fit the engine to the early P38 V8 ZF thus allowing you to use the largest diameter torque converter as you are now using the V8 bellhousing and use this in conjunction with the “stage 2” 4HP24 described above. We are now able to supply these kits at £595 and the 4HP24 autoboxes rebuilt, outright at £1550.

This means you now have the biggest converter which gives you the stronger lockup clutch, lower stall speed so it’s not revving so much when you pull off (and thus less heat generation), with the 24 you have the stronger internals, this is the best box and converter setup and it can be run hydraulically but you are restricted to the shift points set by the box, to get the most out of the engine you can have this box built with electronic control and run it with the Compushift, this allows total control so you can make the vehicle drive perfectly.

Oil Temp Info click here for a guide on oil temps

To see an explanation of our core deposit please click here

IMPORTANT Please note that it is very common for the steel plate which is welded on the Td5 Discovery autobox to be broken. If yours is broken I am afraid we will be unable to accept your converter as an exchange unit and there would be a surcharge of £200 deducted from your core deposit refund.

Please note that the shipping cost within the UK mainland for one unit is £70 which includes collection of your old unit. Sorry we are unable to collect from customers outside of the UK.