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ZF4HP22

£675.00

Product Information

The 4HP22 was used by Landrover in the V8 Defender, Range Rover Classic and the Disco 1, . All our boxes are fully rebuilt including the valve body and come complete with a rebuilt torque converter. To see an explanation of our core deposit please click here
 


Video of a ZF 4HP22 being built


Videos to show what the ZF 4HP22 comes with






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.

This option is an additional £240 when ordered with an autobox or £315 exchange + £ 200 refundable core charge when ordered alone.

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

If you think your Transmission may be running hot, you may want to order on of these


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Sorry we are unable to collect from customers outside of the UK.

Product Code: ZF

Installation Information » (Click to Expand Collapse)

Check List for fitting ZF Autobox

Please note that a good 50% of our "warranty returns" are due to two basic installation errors.

1) Debris and contamination in the oil cooler and oil cooler lines, even if you have flushed them out this is no guarantee they are clean, if the old box has suffered a bad failure you would be wise to replace these.

2) Broken oil pump, by not fitting the torque converter correctly, read below.

Assembly

Check engine to bellhousing and Autobox to transfer case dowels are all fitted.

It is very important that you locate and install your torque converter correctly. One of the most common causes of failure is the torque converter not being located correctly onto the pump before fitting causing the pump to be broken on start up.

To avoid this we would suggest that you stand the autobox upright and lower the torque converter into the bellhousing.

When the torque converter has fully located onto the pump it is essential to then measure the distance from the bellhousing front face to the torque converter feet ( also known as the flange that the flexplate is bolted to).

Once the torque converter is inserted and checked make sure it does not fall forward when offering the autobox up to the engine. Do not be tempted to pull the gearbox into position with the bellhousing bolts, it should fully locate on the engine with no gap between the bellhousing and engine block.

With the autobox fitted to the engine, check that the converter will rotate freely and has a small amount (about 2mm) of end float. Bolt the converter to the flex plate using loctite or similar on the thread of the bolts.

Ensure the breather vents well away from the exhaust.

Oil Fill

Always use a good quality oil, preferably a Dextron III or similar. Put the transfer case in neutral and fill. Start the engine, the oil level will drop immediately, top back up straight away. Move the shifter lever up and down through the gears slowly whilst checking the oil level and topping up as required. Once the level has stabilised, put the transfer case in gear and the unit should now be picking up drive, this is indicated by the engine revs dropping when put in Drive.

Set up

If the vehicle is a Disco I or Range Rover Classic under no circumstances drive with the kickdown cable disconnected, as this will cause premature autobox failure.

Ensure that the shift assembly is set correctly and full travel of the shifter and engagement of all gears is positive, partial shift will cause premature autobox failure.

If the vehicle is a Disco I or Range Rover Classic you may want to adjust the kickdown cable if you want to fine tune the shift pattern, the looser the cable the softer and earlier the shifts, the tighter the cable, the harder and later the shifts.

Torque Converter Depth Table

The box code is the last 3 digits of the second number down on the name plate on the left hand side of the autobox.

Box Code.....................Depth in mm

061................................... 22

064....................................22

065....................................27

332....................................51

593....................................51

699....................................51

727....................................27

728....................................83

740....................................51

741....................................51

742....................................51

744....................................18

748....................................18

747....................................27

757....................................27

759....................................27

763....................................83

764....................................27

765....................................27

766....................................96

767....................................27

768....................................83

769....................................83

773....................................96

Please call if you have any other queries.

Technical Information / FAQ's » (Click to Expand Collapse)

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.

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