ZF auto gearbox upgrade

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dyno
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ZF auto gearbox upgrade

Post by dyno » Sat Mar 18, 2017 7:32 pm

Hi all,

What's most easy or what do you recommend? Is it best to buy a mechanical (hydraulic) switching 4HP22 and fit the stronger gears from a 4HP24 or is it easier to start from a solenoid switching 4HP24 and fit the hydraulic switch block ?

4HP22 as strong as the 4HP24 once fitted with stronger 4HP24 gears?

Anyone a link to where it's explained how to do this conversion ....

Thanks in advance

Dirk



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ChrisJC
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Post by ChrisJC » Mon Mar 20, 2017 8:59 pm

I would get the 4HP24 and then just swap over the valve block etc. But I have never actually done it so there could well be snags on the way....! Like the kickdown cable which isn't there on the electronic version but is on the non-electronic version.

Chris.
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Post by unstable load » Tue Mar 21, 2017 1:44 am

My search skills are coming up short, but there is a gent that has fiddled extensively with the 22 and 24 models with pretty much the same goal over on the Rover forum.
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John

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Post by Robrover » Tue Mar 21, 2017 7:21 am

Take a look at Ashcroft Transmissions site.

Quote:
Ashcroft Transmissions
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, Photo here. 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.Photo here
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.Photo here

"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.

dyno
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Post by dyno » Wed Mar 22, 2017 7:13 am

Thanks all for the info.

I've already been reading the Ashcroft site but I was hoping I can do all myself. For example, fitting the valve block from a 4HP22 into a 4HP24 and leaving most of the rest as it is would be a nice option.

Otherwise, the "mix" of 4HP22 with all strong internals from the 4HP24. Is this more or less plug and play stuff, buying 2 boxes and start mixing or a lot more complex with buying non standard parts?

Anyone using electronic switch on his standard 4HP24. If I can't build anything mechanical, this may be my last option.

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Post by DaveEFI » Wed Mar 22, 2017 9:30 am

MegaSquirt do a gearbox controller which IIRC can be used with the later 4HP. I've not seen one, but sounds fun.
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Post by DaveEFI » Wed Mar 22, 2017 9:30 am

MegaSquirt do a gearbox controller which IIRC can be used with the later 4HP. I've not seen one, but sounds fun.
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Post by dyno » Thu Mar 23, 2017 5:24 pm

Willing to give it a try but I don't want to end in a trial and error situation. Had this before with Megasquirt. Some options are in the ECU, all working correct but take ages before you have setup and working as it should. I remember when I was tuning the idle settings for the original 4 wire Rover 4,6 ltr idle controller.

If I go electronic, I prefer to buy a plug and play system which only need minor tuning to improve the shifting points. Not starting from scratch.

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Post by Eliot » Fri Mar 31, 2017 8:57 pm

I think there's more than one option for aftermarket control of the hp24 - which is the path i would take as you can map the shift points and shift characteristics exactly how you want then.
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Post by DaveEFI » Fri Mar 31, 2017 10:39 pm

Eliot wrote:I think there's more than one option for aftermarket control of the hp24 - which is the path i would take as you can map the shift points and shift characteristics exactly how you want then.
But not if you want a simple plug and play solution - which is apparently what
dyno wants. If you want something custom to your setup, you either pay someone to do it, or learn how to.
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dyno
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Post by dyno » Sat Apr 01, 2017 5:20 pm

Just bought a Jaguar 4hp24 in UK. Seems like it's exact the same as the Rover P38, except different tail and different bellhousing but seems like interchangeable.

Will try to find electronic, plug and play. If not, a local gearbox rebuilder is willing to fit the 4hp22 hydraulic valve block into the 4hp24 and have it switched this way. Hope it's going to work.

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Post by James 33 » Tue Jul 04, 2017 8:55 pm

I have fitted a ZF4hp22 box to my 4.0 v8 Trike. Used a BMW 3 series box then fitted a R/R bellhousing, Torque converter, Flywheel, Sump and pick up pipe. Hope thats of some help.

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Post by Chris » Wed Jul 26, 2017 7:48 pm

Never done this by myself, even though I was employed with ZF in Saarbrücken, Germany. But 8HP45/70/90 were the only boxes I got my fingers on ;)

From a theoretical point of view, I'd recommend to get a 4HP22 unit and change the so called "tower" for the 4HP24 internals.

For uprating swap over the front end, torque converter and bas plate - - and there you go with a mechanical 4HP24.

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