Automatic gearbox questions

dyno · Post by **dyno** » Thu Oct 15, 2015 12:19 pm

I'm in a process of building a Rover V8 4,6 ltr, fast road/rally cam and quad Webers DCOE crossover. I've got plans to use an auto gearbox. I'm totally new to Rover V8 and auto boxes. I had 2 idea's in mind. The car is an older space frame Mondeo look like, +/- 850 - 900 kg (2 wheel drive). Plenty of room to fit virtual anything. Rear axle is Toyota Hilux, any ratio available, currently 4,56/1.

I fit a ZF 4HP24, use electronics to shift at the wheel (or programmed shifts) or have it converted to mechanical shift (from ZF 4HP22). They told me I have to start with a Jaguar ZF 4HP24 gearbox, fit Rover V8 Bellhousing from late 4,6 ltr and use this big Rover torque convertor. Is this correct, does it fit the Jaguar box and which Jag box do I have to select? Any other issues I just can't see? Drive shaft is not a problem.

The person who does rebuild and convert ZF boxes here also told me the ZF 5HP24 is a stronger box to start from. The gears from second to fifth gear are also closer as the one from first to fourth in a 4HP24 gearbox (I would not use the first gear in the 5 speed box, except for loading the car on a trailer etc...). This gearbox can be sifted with paddle at the wheel (and the right ECU of course). Not possible to shift mechanical but is not a problem.

But I don't think this ZF 5HP24 was ever fitted as standard on a classic V8, only the later 4,4 engines. Correct? This will mean, no plug and play bellhousing and also no plug and play torque converter (seems like a different model torque converters on these late type 5 speed. So, is it possible to do this conversion? Anyone ever done it with success?

Or does anyone out there has a better solution? Advice please.

DaveEFI · Post by **DaveEFI** » Thu Oct 15, 2015 1:35 pm

There was one RWD vehicle fitted with an RV8 and 4HP22 - the Sherpa/LDV ambulance etc.

Or you can use one from a Range Rover etc by fitting a tail shaft from a RWD box - Jag, etc.

IIRC, that is the only auto which simply bolts on and can handle the torque of a 4.6. Others can of course be fitted with special bell housings or adaptor plates.

Note - early 4HP boxes were purely mechanical. Later ones a degree of electronic control. Not sure if this matters if you'd going to convert it to manual selection only.

dyno · Post by **dyno** » Thu Oct 15, 2015 2:07 pm

Yes, but seems like the ZF4HP22 is a slightly weaker gearbox. Can be upgrade by using parts out of a ZF4HP24 but indeed, can not be converted to manual shift.

So this means, there is no Jaguar ZF4HP24 gearbox with the same bolt pattern so the rover V8 4,6 ltr bellhousing would fit? And shafts not the same length to drive the torque convertor?

DaveEFI · Post by **DaveEFI** » Thu Oct 15, 2015 3:53 pm

Not really sure. On all the RV8 installations, the bellhousing is a lot deeper than needed to suit the RR transfer box centres. With the TC on spacers from the drive plate. So unless you can source an LDV one, I'd guess you'll have to make one from two.

ChrisJC · Post by **ChrisJC** » Thu Oct 15, 2015 5:24 pm

There was only ever one bellhousing design for the ZF 4HP22 / 4HP24 for the Rover V8. This design covered both Rover and LDV applications.

There were a number of torque converter / flex-plate arrangements for different engines.

If you go for the 4.6 engine, (which only ever came with the 4HP24), there are two flex-plates, one is 36-1 (GEMS engine), and one is 60-2 (Thor engine) for the trigger.

My understanding is that the 4HP24 is stronger and longer than the 4HP22, but not by much. If you are in a 2WD car, I think you will lose traction before breaking the transmission.

I don't know of anybody ever using a 5HP 'box on the Rover V8.

The 4HP24 is electronic only, so that would be best for your steering wheel paddles. Ashcroft Transmissions do a kit.

Chris.

dyno · Post by **dyno** » Thu Oct 15, 2015 9:42 pm

Thanks for the info. So no Jaguar box will do the job as I was told?

I better start with 4x4 ZF4HP24 4,6 ltr Range Rover box and have it converted to 2WD ?

DaveEFI · Post by **DaveEFI** » Thu Oct 15, 2015 9:56 pm

Again I'm not certain, but think you could start with a Jag box, and use the RR input shaft etc and bellhousing. But whatever way you do it, you'll need bits from two boxes anyway.

dyno · Post by **dyno** » Fri Oct 16, 2015 7:53 am

OK, thanks. So no plug and play version possible. Was hoping Jaguar came close. I'll buy a second had Jag box first and see what more will be needed.

If there is anyone willing to sell a Rover V8 4,6 ltr bell housing, I'm a potential buyer.

DaveEFI · Post by **DaveEFI** » Fri Oct 16, 2015 8:43 am

I'd say if I were fitting an auto to a vehicle where it's not going to be simple bolt in job anyway, I'd go for the 5 HP. I have one of these in my daily driver, and never think it could do with an extra ratio. Although I realise many boxes have even more ratios these days.

dyno · Post by **dyno** » Fri Oct 16, 2015 6:52 pm

Correct, 6 and even 7 gears but these kind of boxes don't have separate bell housing and need very complex ECU's to get them running as a stand alone.

The ZF5HP24 I was told to be just possible to do DIY. But in this case it's totally no plug and play. I don't think I want to go this far at the start (unless it was fitted as standard on classic V8). To many others things have to be done and will take a lot of time. Let alone money of course.

Thanks all for the advice.

JSF55 · Post by **JSF55** » Fri Oct 16, 2015 7:46 pm

Bowling and grippo do a shift controller if you can get your head round it all.
I fitted a zf4 hp22 out of a jag, has to be a xj6 2.8 to be right, range rover flex plate and all other bits and torque convertor. the firmness of shift is quite tuneable through the kick down cable. if your using it for any sort of track racing your better of going for a manual box unless something is holding you back ?

dyno · Post by **dyno** » Fri Oct 16, 2015 8:31 pm

Yes, Microsquirt can be used. But there are several ready to fit systems in case I can indeed not get around it.

Good news, I can use this Jag box, bell housing Rover V8 will fit direct? Can I use the big 4,6 ltr torque convertor? Only this Jag box is right, I have to avoid others?

Yes I know, manual box but we want to do something different. I can fit one of my Honda S2000 turbo engines, have twice the power and fit 6 speed seq. box but this is something we already did and everybody already has done.

We want Rover V8 (nothing can beat the sound of a good V8 and the Rover is light), we want quad Webers (nothing can beat the look of quad Webers) and when you get old and lazy, you want auto gearboxes !!!!

Well not totally the reason but my friend was running an auto box with 4,6 ltr (Megasquirt Phil Ringwood) in a trial car and it was damn fast, easy to drive. Box was upgrade ZF4HP22 mechanical switched.

ChrisJC · Post by **ChrisJC** » Fri Oct 16, 2015 9:35 pm

The issue with the Jag boxes is that the governor is set for a higher engine speed than the Rover boxes. The straight 6 engine will rev higher than the V8.

But you could get a Jag box, and fit the rover bellhousing / torque converter / flexplate assy. It would all physically fit. You would probably have to swap the governors over (in the tailcone), and the shift map would be wrong, but if you are going electronic maybe it doesn't matter.

Chris.

dyno · Post by **dyno** » Fri Oct 16, 2015 10:02 pm

Thanks Chris,

We are talking about "any" Jaguar box 4HP22 and 4HP24 or just the one in previous replay (2,8 ltr) ?

JSF55 · Post by **JSF55** » Fri Oct 16, 2015 11:07 pm

No only zf4hp22 will do, the 24 has electronic shift, seemingly 3.2s too, but I would double check the gearbox tag

http://www.ebay.co.uk/itm/1992-JAGUAR-X ... XQUmFSdV61
(nothing to do with me)