Can i change Gearbox from ZF4HP22 4-speed to ZF4HP24 5-speed

Hi folks. I have a Range Rover P38 4.0 SE Auto, 1996. This have ZF4HP22 transmission 4-speed and i want to change to ZF4HP24 5-speed. Is that posible??? Do i need to make much changes???

Isn't the 4HP24 a four speed?

But anyway if your talking about the one that is used in the 4.6 range rover according to Datatek I think the box has slightly different dimensions somewhere but it is doable.

If you're talking about a box that wasn't in the range rover originally then yes I imagine you'll have lots of work to do as the gearbox ECU won't work with another type of gearbox and getting another ECU to talk to the BECM will be a complete pain.

No i have a range rover p38 4.0 se and this version and 2.5 diesel version have 4-speed autogearbox. i have to get that from another range rover p38 4.6 that have 5-speed autogearbox

Yes I'm positive they didn't give the P38 a 5 speed automatic. A 5 speed manual, yes.

I'm sure the fact its named ZF4HP24 means it's four speed. All other ZF automatics are named ZF then the number of gears it has. The last number I have no idea about but I'd guess its something to do with the amount of torque it can handle or something.

My 4.6 automatic is a 4 speed. I thought they all were too.

The ZF4HP24 is stronger than the ZF4HP22 to cope with the increased torque of the 4.6 engine. The gear change points and ratios might be a bit different, but the number of gears is still 4. It's also a bit longer.

I'm not sure how the extra length is accommodated, could be just different length drive shafts from the transfer box to the differentials, but I'm not sure.

You'd also need to change the gearbox ECU and maybe even tell the BECM too.

Not worth the effort to change over IMO. You're not going to get an extra gear.

Is your gearbox broken? If so it would be fine to replace with a ZF4HP22. Chipped diesels might benefit from the ZF4HP24 but I don't think the 4.0 will.
If it's not broken it might be a lot of work for little benefit

Reading RAVE there are a few differences between the two the spec changed at MY99 too.

Number of gears are still 4 though.

Ok folks thnx . Im was thinking that will be a big difference . My autogearbox is not broke. Its all ok.

aollaku said:

No i have a range rover p38 4.0 se and this version and 2.5 diesel version have 4-speed autogearbox. i have to get that from another range rover p38 4.6 that have 5-speed autogearbox

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The 4.6 has the ZF4HP24 which is a 4 speed but stonger version of the HP22 It can be fitted to the diesel using the diesel bell housing and torque convertor, overall length is the same as there is and adaptor plate that accomodates the length difference although the 065 version of the HP24 is exactly the same length as the HP22 and uses the same adaptor plate. Change points are controlled by the ECU so will remain the same.

I think what OP means is the ZF5HP24 box used in the L322 between '02 & '05 perhaps? Thats a 5 speed autobox...

Baiman said:

I think what OP means is the ZF5HP24 box used in the L322 between '02 & '05 perhaps? Thats a 5 speed autobox...

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I also think the OP gave up considering the thread is over 5 years old

Baiman said:

I think what OP means is the ZF5HP24 box used in the L322 between '02 & '05 perhaps? Thats a 5 speed autobox...

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hmmmm....

Get out!!

Mark Piercy said:

View attachment 160434 hmmmm....

Get out!!

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Didnt seem quite so obvious to anyone other than you or I...

Purely from an academic perspective I seem to remember the M51 engine went in the Vauxhall Omega. Now, I cannot remember if the 4-speed auto in it was the HP22 gearbox but I do remember the continental petrol autoboxes had the 5-speed version (or some did) and all the old grotty 4-speeds went to the UK market. I remember the box in the 3.0 petrol was stronger than the one on the oil burner and had a different ratio for the rear diff so that might have been the HP24.

Grrrrrr said:

Purely from an academic perspective I seem to remember the M51 engine went in the Vauxhall Omega. Now, I cannot remember if the 4-speed auto in it was the HP22 gearbox but I do remember the continental petrol autoboxes had the 5-speed version (or some did) and all the old grotty 4-speeds went to the UK market. I remember the box in the 3.0 petrol was stronger than the one on the oil burner and had a different ratio for the rear diff so that might have been the HP24.

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I doubt if you can fit a later 5 speed box to a pre 1999 P38 maybe after 1999 but not sure. Even if you fit a HP 24 in place of a HP 22 to a vehicle prior to 1999, all you will get is a stronger box, you will not get the self diagnosis and adaptive adjustments the HP24 controller is capable of. Because it will have to run off the HP22 controller which does not have this facility. The HP24 controller needs CANBUS, pre 1999 models do not have this.

Grrrrrr said:

Purely from an academic perspective I seem to remember the M51 engine went in the Vauxhall Omega. Now, I cannot remember if the 4-speed auto in it was the HP22 gearbox but I do remember the continental petrol autoboxes had the 5-speed version (or some did) and all the old grotty 4-speeds went to the UK market. I remember the box in the 3.0 petrol was stronger than the one on the oil burner and had a different ratio for the rear diff so that might have been the HP24.

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GM boxes Grrrrrrrrr.
Ar25 for the diesel and 2.0i petrol and the ar35 for the V6.3.0i. the ar25 was way to weak and the diesel would lunch it!!! The trick was to get the ar35 use the ar25 bell housing and shove it in the hole. You could even use the existing ECU.oh and both 4speed with the torque lockup.

Mark Piercy said:

GM boxes Grrrrrrrrr.
Ar25 for the diesel and 2.0i petrol and the ar35 for the V6.3.0i. the ar25 was way to weak and the diesel would lunch it!!! The trick was to get the ar35 use the ar25 bell housing and shove it in the hole. You could even use the existing ECU.oh and both 4speed with the torque lockup.

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That was it! Yes, that would make sense. I remember a lot fo the oil burner guys chipping theirs and trashing their boxes.