ZF 4HP22 automatic trasmission

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Ugo
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Location: Italy

ZF 4HP22 automatic trasmission

Post by Ugo »

Hey TD owners,

The ZF 4HP22 automatic trasmission has been used in quite a lot of cars and light trucks other than the Pinzguauer, and it seems that it suffers from some problems due to design weakness.
Specifically, on many internet forums several cases are reported about overheating and about clutch damage when revving the engine in P or N.
It appears that the transmission oil pump is not fully deactivated when the trasmission is shifted from D to P or N, causing a partial clutch contact and wear.
BMW issued an alert: engine should be shut off for 1 minute, with transmission in P or N, for full pump depressurization before revving up (e.g. for smoke test).

Is this known by Pinz TD community?

Ugo
Torino, Italy
1990 716K
Tads
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Location: Telford, UK

Post by Tads »

This doesn't seem to be a problem with the auto in the TD Pinz. Most common problem is sticking in first when cold - usually caused by contamination of the governor at the rear of the box which is before the filter for reasons known only to ZF!

Other problems - park pawl breaks if abused, clutch packs let go occasionally .

All in all though it's a pretty reliable box - Check the breather on the top of the box at the back end occasionally to ensure it is connected, other wise dirt and water can enter. Change the oil regularly and make sure the level is correct. Do this and they'll last a long while. If it does let go there's lots of old range rovers to get a replacement box from - only problem is that the 1st & 2nd gears are slightly different ratios.
Ugo
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Location: Italy

Post by Ugo »

Thanks Tads for help.

Ugo
rockwood
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Post by rockwood »

The ZF4hp22 has been used in 7 series BMW and Land Rovers for years. Its a tough box to kill off, but the advice is not to leave the engine running and in Park for any length of time. Neutral is the preferred slot.
Anthony
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Post by Anthony »

Hi ugo,

Have you asked you question on Robi's Pinzgauer Forum? There are a few Turbo Diesel 716/718 owners on that site who may be able to answer you.

http://pinzforum.kiruna.de/index.php
Anthony
GB
Pinz_M
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Post by Pinz_M »

I have successfully overhauled this transmission. It was from a BMW. There is a fix for that, ZF now supplies teflon rings for the top shaft instead of metal ones, they keep the oil pressure away from the clutches.

You can also use 4hp 24 instead of 4hp 22.. 4hp 24 was for bigger V12's and was much more beefy to handle the torque. You will only have to change the bell housing. This info is true for bmws, I dont know what kind of 4hp 22 is found in pinz.... as land rovers have a bit different looking boxes.
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fesm_ndt
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Post by fesm_ndt »

Is the bellhousing, driveplate etc, pinz specific?
Regards

Mike
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fesm_ndt
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Post by fesm_ndt »

Tads wrote:only problem is that the 1st & 2nd gears are slightly different ratios.
battling through the ZF part numbers and found a lot of things are same as Rover. Would help when I get a Rover specific auto parts manual. But definately clucth packs have the same numbers.

the repair for the design fault is teflon seals and drilling a small relief hole

of real interest is that the ZF 4HP24 is a far superior box and it's innards have been fitted into a ZF 4H22 case (apparently the centre case is the same). The bit I am interested in now is if the Pinz bits will bolt onto the ZF 4HP24 central case.
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Mike
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fesm_ndt
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Post by fesm_ndt »

I managed to get the ZF parts manuals so by comparing a lot of it is exactly the same as Land Rover

The only really major difference is in 2 of the planetary gear sets which is I guess where the gear ratio difference comes in. These could possibly be in Jaguar, BMW or Volvo boxes (haven't searched that far as yet).

Not a major concern as if 'just' rebuilding a box the rebuild kit with clutches is the same. Control unit has different pressure settings

The torque convertor so far appears Pinz specific, but torque convertors can be rebuilt at 245 Nm/2000rpm-1

If upgrading the box you can:

- fit the teflon seals and drill a small hole
- fit the ZF24 pump (makes the gear box 15mm longer and the cooling line connections are M18 x 1.5 mm as opposed to the original M16 x 1.5mm)
- Can fit the ZF24 clutches and internals into the ZF22 casing as the 24 stuff is much stronger (some differences so still in discussions with ZF)

If you are ok with the Land Rover ratios (I would love to know what they are like actually????????

- get a ZF24 box fit the pinz input shaft, control unit and rear housing. You have to fit the control unit from the 22 box as 24's are electric. Several versions of the LR 24 exist, just a matter of matching parts.

Anyway if anyone knows the ratios for a Land Rover box in comparision to a Pinz and what does it affect I would be very interested????

Just thought I would update on the information I found out this week after meeting the correct ZF guy
Regards

Mike
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fesm_ndt
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Post by fesm_ndt »

Daft of me the ZF manuals have the info:

Land Rover ZF 4HP22 and ZF 4HP24

1st 2.48, 2nd 1.48, 3rd 1.00, 4th 0.73 and R 2.09

Pinz ZF 4HP22

1st 2.73, 2nd 1.56, 3rd 1.00, 4th 0.73 and R 2.09

:lol: :D :lol:
Regards

Mike
(Project Gimpy 2)
TonyC
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Post by TonyC »

fesm_ndt wrote:
- get a ZF24 box fit the pinz input shaft, control unit and rear housing. You have to fit the control unit from the 22 box as 24's are electric. Several versions of the LR 24 exist, just a matter of matching parts.
Mike,
The electronic box can be controlled with a Compushift

http://www.ashcroft-transmissions.co.uk/part_80.html

Ashcroft, who are in the UK, are well regarded even here in Aus as knowing their Land Rover transmissions.
If you have any queries I would give them a call/email

Tony
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fesm_ndt
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Post by fesm_ndt »

will have a look at that, cheers . Tried to send an attachment to you earlier but 20mb your email didnt like it. I'll see if i can reduce it tomorrow as been on the road 16 hours

It was via an ashcroft blurb that I found the 24 bits fit into a 22. Kinda thinking the gear ratio differences in 1st and 2nd gear are irrelevant as I am not going to be towing a 105mm. Was hoping to meet up with the ZF guy today but no luck as had to go to a business trip
Regards

Mike
(Project Gimpy 2)
Tads
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Post by Tads »

Will post a fuller post later, but the 5cyl Pinz box is basically HP24 internals in the 22 casing. Later production boxes even use the Rover gear ratios as ZF moved production to a smaller facility and standardised on a single ratio for all the remaining customers which happened to be the Rover ratios as they placed the largest orders. As noted, the difference isn't really noticeable on lightly laden vehicles.
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fesm_ndt
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Post by fesm_ndt »

Another bit of info I got the other day if you get your torque convertor rebuilt:

- The drive torque of the torque convertor is 245 Nm/2000rpm-1
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Mike
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fesm_ndt
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Post by fesm_ndt »

Well got most the bits but will have to wait until I can find another Land Rover ZF 4HP24 (P.N. 1043 030 065) to rip to pieces as missing:

1043 222 089 INTERM.PLATE (a bit weird as the breakdown numbers say it’s the same)

1043 210 001 PUMP

0734 313 061 H O-RING

1043 202 203 INPUT SHAFT

So if anyone has a mate who wrecks Land Rovers let me know :D
Regards

Mike
(Project Gimpy 2)
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