Thread: what diff centres for a S111

You have a couple of choices either use Range Rover Diffs or use a set of higher ratio transfer gears.
Are we talking about a SWB or a LWB if you are talking SWB then any Range Rover Classic diffs up til about 1992 (or is it 1993) should fit.
If you are talking LWB well thats a whole new world as the rear Salisbury is not compatible with an Range Rover centre, but you could get a Stage 1 Salisbury that is the same ratio as the Range Rover classic.
You could also try and find an overdrive

Originally Posted by djam1

You have a couple of choices either use Range Rover Diffs or use a set of higher ratio transfer gears.
Are we talking about a SWB or a LWB if you are talking SWB then any Range Rover Classic diffs up til about 1992 (or is it 1993) should fit.
If you are talking LWB well thats a whole new world as the rear Salisbury is not compatible with an Range Rover centre, but you could get a Stage 1 Salisbury that is the same ratio as the Range Rover classic.
You could also try and find an overdrive

interesting. The vehicle is a LWB 1980.

If I went down the high-speed transfer case upgrade what parts would I be looking for, what is the result and what would it cost roughly?

cheers
Jim

Originally Posted by Jimmy

interesting. The vehicle is a LWB 1980.

If I went down the high-speed transfer case upgrade what parts would I be looking for, what is the result and what would it cost roughly?

cheers
Jim

The high speed transfer case conversion costs $1100 in Australia (I've been recently quoted by two companies). I was also told that it is only worth doing if you are sticking with an original 2.25 motor.

Changing to 3.54 diffs means even less rpm on the highway than the transfer case conversion, but the low range ratio is lifted as well. This does not work well with an original 2.25, but for a more powerful engine it is no problem.

The Rover 3.54 10 spline centres can be easily swapped with the original Rover S3 centres. There is a locating dowell that has to be removed.

This will originally have had a Rover six in it, so disregard the comments about original 2.25. But the diffs are identical between the six and the four.

To change the gearing to make it more suitable for the Holden engine, you need a higher ratio. This can be achieved by changing the transfer case ratio as suggested above, by changing the diffs, or by fitting an overdrive.

The cheapest solution would be to swap your rear axle for a Rover one from a 2a and replace both diffs with RR ones. But this means you no longer have the much tougher Salisbury rear axle, which is probably not a desirable outcome.

If you can find a S3 Stage 1 rear axle (same ratio as RR) and swap that plus a RR front, would probably be the most satisfactory result, but these axles are fairly scarce.

The high speed transfer case option is probably workable as well, but I have no direct experience of this.

The simplest and quickest "fix" is to fit an overdrive. The problem is that the most commonly available overdrive, the Fairey, is fairly fragile, and you need to be very careful buying a secondhand one (all parts are available, but not cheap). If you fins a Toro, jump on it.

All of these suggestions except the first will cost you over $1000 plus labour.

John

The Rocky Mountain, Roverdrive looks the goods.

About $1800AU and considerably easier to fit than changing diff-centres.

Good suggestion John!

Originally Posted by chazza

The Rocky Mountain, Roverdrive looks the goods.

The Rocky Mountain overdrive is most certainly more superior than either the Farey or Toro overdrives. The Farey are built from gear sets out of the Rover TC 2000 car where the Rocky Mountain is an epicyclic box using gear sets from automatic gear boxes built to withstand big yank V8s. The RM also runs quieter than the others.

However like all overdrives, they prevent you from using a PTO winch.

Diana

Originally Posted by Lotz-A-Landies

.....

However like all overdrives, they prevent you from using a PTO winch.

Diana

Not necessarily - you can use a bottom PTO - if you can find one.

John

Originally Posted by Lotz-A-Landies

However like all overdrives, they prevent you from using a PTO winch.

Diana

Couldn't you still use a capstan winch as it is driven off the crankshaft, or a hydraulic winch driven off the engine?

I take your point; however;

Cheers Charlie