Which transmission and transfer case to use?

[Peterc5561]

Please help, I'm somewhat new to all this and have spent hours and hours looking and reading to try and find my way. But i have to ask before I go nuts! ( oh no, i'm all ready there, i'v got an old Range Rover :(.)

I'm looking at the options of altering my 85 Rangie. I've had it for two years. Its not quite stock, at the moment its a stroked 4.7 carbies 5speed with Roberts (ARB) diff locks. 10 spline axels with D1 alloy rims and 245/75/16 tyers.
And heres what I want to do.

Convert to an Auto, with larger tyers 32s or 33s, a strong transfer case, and high ratio diffs.

So far I've found a rebuilt LT230 that was out of an auto with new everything! and rebuilt diffs out of an 84 with diff centres from a S11 Landy that are 4.7 to 1

The help i need is advice on-
1, What auto is best suited to the job? What are my options?
2, Have i got the right Transfer case? How do you tell the difference between models?
3, Are the new diffs at 4.7 to1 ratio OK?

Thanks for any help or at least point me in the right direction so I can find out.:confused:
Pete

[BigJon]

I think you will break those diffs. Series diffs are not very strong.
As far as an auto, the ZF 4 speed should be ok with that setup.

[langy]

.. a little extra info for your remaining two questions.

T/C - there are three choices in LT230 ratios. 1.4, 1.2 and (rare) 1.0 to 1 high range. Low range is the same in all three. Others may know the various serial numbers that denote which is which, but generally defenders have the lowest gearing at 1.4:1 , followed by disco's & Rangies at 1.22, and early auto rangies at roughly 1:1. If you go up in tyre size, @ 31 inch, you won't have to change anything - @ 33 inchs there are two things generally done to balance it out - either fit 4.11:1 crown wheel/pinions to your lockers or find a defender T/C.

If it was me, I'd do the auto conversion first using the rebuilt TC - test it out with the standard wheels, then test it with 33's (If they fit - you may have to do some sort of lift & cutting to get them on) and see how the stroked engine and auto handle the change in tyre size. It may be that the extra HP compensates for the difference in final drive ratio.

Of course, if you have the cash - go buy a set of 4.11 CWP's and have them fitted to your lockers. I tend to agree with BJ that it may not be a good idea to use series diffs behind a V8.

[isuzurover]

What the others have said. I would go with a ZF auto, 1.2:1 LT230, and 4.11 gears.

4.7 ring and pinions have a very small pinion with fine teeth, making them weak. I know someone who used them in a comp rangie, and amazingly managed to do a few comps without breaking, but that is very unusual. A 4.75:1 ratio is available aftermarket, which is stronger.

[Bush65]

There are a quite a few different LT230's.

The early ones were LT230R (roller bearings in intermediate gears).
Then later the LT230T (taper roller bearings for intermediate gears), which is my preference.
Newer discos have the LT230Q (quiet gears) - has taper roller bearings, but IMHO the teeth are not as strong.

You can tell if it has taper roller bearings, because there is a large nut at the rear end of the intermediate shaft (to adjust the bearing preload).

I have a defender LT230 in my rangie. The 1.4:1 high ratio is better with larger tyres on the highway. This does not help with low range.

I fitted 4.11:1 cw&p in my disco diffs, which is the better way to go IMHO, because it lowers both high and low range.

As others have said the 4.7:1 cw&p is too weak.

With larger tyres, you should consider upgrading from the 10 spline axles. You can change the side gears, or get macnamarra to respline your 10 spline side gears to 24 spline.

The zf auto box from a rangie or disco should be good enough for your engine. They can be upgraded (clutch packs mainly) if you intend to drive it hard - but your diffs and axles will probably let you down 1st.

[Peterc5561]

Thanks very much for the info/advice.:)

What model rangies came out with ZF Autos?

And I thought i'd read that Blknight.aus (http://www.aulro.com/afvb/member.php?u=13085) had a dream Mud Rangie with,
3.9lt motor carbies torqueflight auto LT230? and 4.7 diffs with maybe 35" tyers.:eek:

Does any body know?

Another Question- If an Auto torqueflite 3sp has been sitting for two years ie not driven around, would it be stuffed? or would it be OK? its done 390,000km

Thanks again, Pete;)

[Bush65]

Sorry I can't help with your questions.

From all accounts the torqueflite sucks a good bit of power and does not have overdrive. The zf is much better suited to rovers.