Auto Troopy Gearing

In a 78 Series you are doing 1,000 rpm per 40 km/hr in 5th gear.

Therefore at 100 km/hr my 78 would be doing about 2,500 rpm.

Yours sounds about right.

Hope that helps.

As said.
Thats right 40kph per 1000

Hi RB, Sounds like it's the correct RPM but you bring up and interesting subject. I'd love the new 70 series but it's only available in manual also. Not withstanding your scenario I'd love an auto for towing but I understand the 70 series to be discontinued in the future.? The new 200 Series Turbo Diesel does 1600-1700 rpm at 113KMh which is around 1000 rpm lower which shows you how things have changed with more gearing. You may be able to change the diff ratios to lower the rpm but I'm not sure how that would work with the 75 Series engine.?

rb30e,

A cheaper alternative might be to change the ratios in your transfer case. I looked at this a few years back, but still haven't done anything.

Terrain Tamer make a number of ratios to suit 80 series and others, and they offer one that keeps the same low-range ratios but high range is reduced by 9%. This gives, from memory, about 2100rpm @ 100kph. The new gear set is a direct changeover, I believe, with no machining required.

Mark's Adapters make some similar products, but am unsure of their ratio choices. Also their system is more sophisticated, and requires some machining to accommodate the new bearing structure.

Might be a cheaper alternative to sourcing a 5 speed auto box?

Bob.