Classic Automatic Gearbox for RR Classic

roge · Jun 19, 2020

Hi I have a 1974 Range Rover Classic, which has a 2.5TDI engine, with Chysler 3 speed automaticgearbox. I got a 3.5 V8 EFI engine from a Rover SD1, to go into it.
This is my first venture with a RR. I was wondering what is the best automatic gearbox that I can put into the RR with the 3.5 V8 EFI engine ?

norseman · Jun 19, 2020

roge said:
Hi I have a 1974 Range Rover Classic, which has a 2.5TDI engine, with Chysler 3 speed automaticgearbox. I got a 3.5 V8 EFI engine from a Rover SD1, to go into it.
This is my first venture with a RR. I was wondering what is the best automatic gearbox that I can put into the RR with the 3.5 V8 EFI engine ?

The ZF HP22 that would have been mated to the engine from the factory?
I believe the earlier transmission tunnels were wider to accommodate the physical size of the 3sp. The floor pan was later ('85?) standardised to accept either the ZF or a manual 'box. I'm assuming the V8 blocks are the same, doubtless others will be along with technical advice.

kds · Jun 20, 2020

Dont think 1974 classic would have had a 2.5tdi in it to start with so out of interest what engine is it ?

roge · Jun 20, 2020

The 3.5 v8 is from a rover sd1 and has a 3 speed automatic 2 wheel drive gearbox on it, as far as I can tell. The 1974 classic originally had a 3.5 but someone had changed it out for a 2.5 tdi before I got it.
Is the later ZF 4HP24 automatic gearbox an option for the 3.5 V8 efi too ?

Henry_b · Jun 20, 2020

The SD1 will have the Borg Warner 65 auto..

The 3spd Chrysler Torqueflite was fitted to the early 80s and late 70s 2/4 door 3.5..

It was a good box, but sucked all the power out of the carb'd 3.5

The EFI 1985+ RRC had the mechanical ZF4hp22 the ZF4hp24 was fitted to the 4,6 P38

roge · Jun 20, 2020

Thanks for that. Can the ZF4HP24 auto be fitted to the 3.5 V8 efi ?

roge · Jun 20, 2020

norseman said:
The ZF HP22 that would have been mated to the engine from the factory?
I believe the earlier transmission tunnels were wider to accommodate the physical size of the 3sp. The floor pan was later ('85?) standardised to accept either the ZF or a manual 'box. I'm assuming the V8 blocks are the same, doubtless others will be along with technical advice.

Yes the top of the transmission tunnel does look like it was badly patched on.. Alot of screws and bolts all over the place really..

Datatek · Jun 20, 2020

roge said:
Thanks for that. Can the ZF4HP24 auto be fitted to the 3.5 V8 efi ?

The ZF4HP24 is electronically controlled, mechanically it will fit but sorting the required sensor inputs for the ECU would be a challenge. The early HP22 was mechanically controlled, later becoming the HP22e with electronic control.

roge · Jun 20, 2020

Thank you, I think the ZF4HP24 is the route I will go down first .. nobody said it was gonna be easy

Datatek · Jun 20, 2020

roge said:
Thank you, I think the ZF4HP24 is the route I will go down first .. nobody said it was gonna be easy

You need to check that it will mate with your transfer box.

norseman · Jun 20, 2020

Henry_b said:
The SD1 will have the Borg Warner 65 auto..
The 3spd Chrysler Torqueflite was fitted to the early 80s and late 70s 2/4 door 3.5.. It was a good box, but sucked all the power out of the carb'd 3.5
The EFI 1985+ RRC had the mechanical ZF4hp22 the ZF4hp24 was fitted to the 4,6 P38

Chrysler 'box also fitted to the US Army's Hummvee, good solid 'box but, as you say, a power-sapper.
I believe Ashcrofts can re-build a 4hp22 with hp24 internals.

Datatek · Jun 20, 2020

norseman said:
Chrysler 'box also fitted to the US Army's Hummvee, good solid 'box but, as you say, a power-sapper.
I believe Ashcrofts can re-build a 4hp22 with hp24 internals.

Yes Ashcroft do do the upgrade, the casings on the later boxes are the same, expensive though.

norseman · Jun 20, 2020

roge said:
The 1974 classic originally had a 3.5 but someone had changed it out for a 2.5 tdi before I got it.

Philistine (not you … the PO)

Click to expand...

kds · Jun 20, 2020

Not kidding, should have at least put a Perkins 4236 (3.8 liters ) in it !

norseman · Jun 20, 2020

kds said:
Not kidding, should have at least put a Perkins 4236 (3.8 liters ) in it !

No comment.

roge · Jun 22, 2020

I checked the transfer box - serial no. 28D. It is LT230 type T, ratio 1.222, used on RR classic 86 onwards and disco 1. Hopefully it will mate with ZF4HP24 auto gearbox..

jamesmartin · Jun 22, 2020

roge said:
I checked the transfer box - serial no. 28D. It is LT230 type T, ratio 1.222, used on RR classic 86 onwards and disco 1. Hopefully it will mate with ZF4HP24 auto gearbox..

lt230 wont fit on a std p38 box

roge · Jun 22, 2020

Ok. Is there much difference, performance wise between the 22 box and the 24 box ? I've read the 24 box is stronger.

Datatek · Jun 22, 2020

roge said:
Ok. Is there much difference, performance wise between the 22 box and the 24 box ? I've read the 24 box is stronger.

The only difference between the HP22 and HP24 is the power it will handle, HP22 should be adequate for the power & torque of the 3.5 V8 IMO.

300bhp/ton · Jun 22, 2020

Or if you'd like a vehicle that is faster, more fun and has potential to use less fuel. Look at fitting a 5 speed manual.

Classic Automatic Gearbox for RR Classic

Member

Well-Known Member

Well-Known Member

Member

Think outside, no box required.

Member

Member

Well-Known Member

Member

Well-Known Member

Well-Known Member

Well-Known Member

Well-Known Member

Well-Known Member

Well-Known Member

Member

Well-Known Member

Member

Well-Known Member

Well-Known Member

Similar threads