The 4HP22 was used by Landrover from 1986 through to 1998 and was fitted to the V8"s and the TDi"s.
All our boxes are fully rebuilt including the valve body and come complete with a rebuilt torque converter.
The core charge for this unit is £300, (if your unit is a 744 or 748 the core charge will be £500) refundable on receipt of your exchange unit which must be like for like, complete and not stripped and with the casing intact. Surcharges will apply if your exchange unit is not as detailed above
Fitting Service We are able to offer a same-day fitting service (the work is sub-contracted to a fitting station near Luton). This price is all-inclusive and includes a remanufactured unit, torque convertor,oil, removal and refit, VAT and free use of a courtesy car. £1081
Please note that if you also require a transfer box just add the unit cost to the above; there will be no additional fitting charge for this.
Technical Information
We have recently (now July 05) made 2 considerable advances in our ZF autoboxes.
A common problem with all ZF 4HP22/24 boxes is the failure of the one way "sprag" clutch. Once the cams in this one way sprag clutch "flip" the unit will slip both ways resulting in the vehicle only pulling off with the shifter in position "1" not "D" and driving OK when shifted up to position 2,3 and D until you stop then you need to pull it back to "1" to start off again. It is not feasible to change this unit in each rebuild as this one part is approx £ 400. By disassembling the "sealed unit" we were able to examine the profile of the cams and understand how they work, from here the challenge was to find another cam from another type of autobox that would fit and had the correct profile to make the unit stronger by not allowing the cams to flip. After quite a lot of searching we found one, "re-cammed" some of these clutches and thoroughly tested them, we have not had one fail since. This is an example of how we are able to use our engineering background to understand a problem and cost effectively make the unit stronger without having to raise our prices.
We have also recently invested £ 20,000 in a "Hydra-Test" machine. This machine allows us to do 2 things. Firstly once the valve body has been rebuilt we are able to fit it to a plate on the test rig and run the valve body through its cycle with 45 deg pre-heated oil to simulate as close as we can get to "real world conditions" The hydraulic valve bodies are run through manually by winding a valve to simulate the governor increasing in speed and various pressure gauges are monitored to see that the valve body is applying the correct clutches at the correct pressures. When testing the electronic ZF valve bodies once the solenoids are all tested this cycling procedure can initially be run through manually to check all is well then the computer can run up to 100 full run cycles going from 1st, 2nd, 3rd, 4th and lock up down to 1st again to ensure no valve are sticking and the solenoids are not failing when hot and working hard.
As part of the test proceedure we also fit a test plate to the autobox in place of the valve body and apply heated oil at pressure to check we have no leakage or pressure drop on any of the clutch packs.
This machine has enabled us to improve the quality of our boxes by identifying any potential faults or problems before the box reaches the customer.
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,
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 £ 595 or £ 645, 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 £ 595 or £ 645, depending if the box is hydraulic or electronic.
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
The converter has a lock up clutch inside and the smaller one struggles to cope with a stock engine, never mind a tuned one.
When the "stage 2" ZF is being used with a V8 or 2.8 TGV you have the option of using the larger diameter 4.6 torque converter at no additional cost but on a V8 you will also need the 4.6 boss and flexplate assy to match the bigger converter. When using on the 2.8 be sure to order the conversion kit to fit the bigger 4.6 converter. This bigger converter is recommended on the big V8"s and the 2.8 as it keeps the revs and heat down.
If you have a tuned TD5 engine, in addition to the stage 1 or 2 options mentioned above we are now able to replace the "Small" diameter torque converter for the "Medium" diameter one. This gives you the benefit of the larger lock up clutch and the lower stall speed V8 torque converter which will take up drive earlier. This option is an additional £ 250.
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 thus allowing you to use the largest diameter torque converter and use this in conjunction with the "stage 2" 4HP24 described above. We are now able to supply these kits at £ 545 and the 4HP24 autoboxes rebuilt, outright at £ 1350.
Oil Temp Info
click here for a guide on oil temps
