Auto for RV8

DaveEFI · Post by **DaveEFI** » Mon Apr 05, 2010 6:59 pm

I have an SD1 Rover with a standard 3.5 EFI engine - apart from a MegaSquirt. It's currently fitted with a GM TH 180 3 speed auto and I'd like something better. Like the ZF 5 speed auto in my other car. Sadly, Land Rover never fitted a ZF 5 speed, and the 4 speed they did fit fouls the bulkhead due to the deep bell housing. And I'd rather not get into modifying that.
So how about a GM 5 speed? The TH 180 has a removable bellhousing - does the GM 5 speed have this too? The ZF is an all in one casting. It seems to me it would be easier to modify a box where the bell housing detaches.

I realise there will be issues with an electronic control box - but at the moment I'm more concerned with the mechanical ones.

ChrisJC · Post by **ChrisJC** » Mon Apr 05, 2010 8:13 pm

You could get a car version of the ZF4HP22 with a different bellhousing and make an adaptor plate up. Or just get a different bellhousing and stick it on a Sherpa 4HP22 so you get the 2WD with the right valving for the V8.

The bellhousings are interchangeable on the ZF4HP22.

Chris.

DaveEFI · Post by **DaveEFI** » Mon Apr 05, 2010 10:28 pm

ChrisJC wrote:You could get a car version of the ZF4HP22 with a different bellhousing and make an adaptor plate up. Or just get a different bellhousing and stick it on a Sherpa 4HP22 so you get the 2WD with the right valving for the V8.

The bellhousings are interchangeable on the ZF4HP22.

Chris.

Thing is I'd like to go to a 5 speed anyway. How do you actually make sure the 'box is centred properly if using an adaptor plate? And how thick would it have to be?

BTW, think a RWD tailshaft can be fitted to the Rangie ZF. Not sure if this involves changing the mainshaft, though.

CastleMGBV8 · Post by **CastleMGBV8** » Tue Apr 06, 2010 12:10 am

Dave,

There an interesting thread running on the British V8 forum (in the USA) at the moment, this one mainly re fitting a 5 sp modern auto box but there are other american boxes that can be made to work such as the TH200R but that Lexus? box Jim B is talking about is very interesting and quicker than you can change manually.

http://forum.britishv8.org/read.php?6,15171,page=1

You will find the guys very helpful re matching up bellhousings to mate to a Rover V8 as a lot of the guys run them and Buicks which have the same bolt pattern.

The TH180 is a presumably an american box so you might get lucky and be able to use the bellhousing with a later GM box.

Kevin.

DaveEFI · Post by **DaveEFI** » Tue Apr 06, 2010 8:07 am

CastleMGBV8 wrote:Dave,

There an interesting thread running on the British V8 forum (in the USA) at the moment, this one mainly re fitting a 5 sp modern auto box but there are other american boxes that can be made to work such as the TH200R but that Lexus? box Jim B is talking about is very interesting and quicker than you can change manually.

http://forum.britishv8.org/read.php?6,15171,page=1

You will find the guys very helpful re matching up bellhousings to mate to a Rover V8 as a lot of the guys run them and Buicks which have the same bolt pattern.

The TH180 is a presumably an american box so you might get lucky and be able to use the bellhousing with a later GM box.

Kevin.

Thanks for that Kevin - they seem to have as many answers as I have questions.

Cost is of course an issue - as is bodywork mods, as I don't have a garage, and don't want the car disabled for long periods. So my ideal would be to modify whatever ready to swap.
GM went out of favour with UK makers - for example the first 4 speed Vauxhall used was an Aisin Warner. So later ones aren't going to pop up often in breakers.
Ideally, I'd like to use a 5HP18 since I know and like it. Cheap secondhand - I already have one, and it will fit the transmission tunnel. After market ECU available. But it's marginal torque wise for the RV8, and has a one piece casing.

But if a GM 5L40E would fit the 180 bell housing easily, it might be worth searching one out.

Eliot · Post by **Eliot** » Tue Apr 06, 2010 9:54 pm

I had a 5HP24 from a BMW540 for sale until very recently... Big old thing though.

DaveEFI · Post by **DaveEFI** » Tue Apr 06, 2010 10:32 pm

Eliot wrote:I had a 5HP24 from a BMW540 for sale until very recently... Big old thing though.

Yes. Think it can handle the largest engines. The 5HP18 is not much larger than my current 3 speed GM - and looks like it would fit in the available space. I believe they can be beefed up too with stronger clutches.

Eliot · Post by **Eliot** » Wed Apr 07, 2010 7:18 am

Then I guess it depends on the power output of your engine, how you program the box and how you drive it.
As its electronic, you can raise the line pressure a little bit (10-20%) and reduce the shift times to give a firmer change which is easier on the clutches.

the box will take around 228ft-lb so, not a million miles away from the output of a rv8.