4 speed VS 5 Speed

[abosely]

What would be gained from swapping a 4 sp tranny out for a 5 sp tranny in an Troopie HJ45 with a 12-HT(Aus. spec) .
It would be more of an expedition type of vehicle (http://forum.ih8mud.com/#) ie. loaded heavily and pulling an expedition type trailer a lot.

Ok, I know the short answer, a 5th gear:D . Mileage would be better or increased cruse speed? If I can get 65mph cruise speed that would be fine.

But, I am wondering about practical gain based on type driving (http://forum.ih8mud.com/#) it will get.

I have read that the H55 should not be ran in 5th gear when pulling a trailer. Even without a trailer the Troopie will be loaded pretty heavily most of the time, so would be similar to a FJ 40 with a trailer. If this is correct I would not be able to use 5th gear much.

I would put the correct gearing in if needed. I will run either 285/75 R16s or 33x12.50s at most.

Would there be any real gain?

Allen

[Sixtys Guy]

I have a HJ60 with the 5 speed. When I tow my caravan which is approximately 1300kg I don't use 5th gear. Apart from it being apparently 'weak' it isn't really practical as I find that cruising between 90-100km 4th is fine.

[Bumpy]

Just do the math.
Is it your daily driver and do you do highway driving? If yes and it is heavily loaded then you won't use 5th much. Consider the initial cost for the change over and try and work out a fuel saving based on the outlay cost to get an idea as to how many k's you have to drive to break even. I have an FJ45 with a holden 253. Revs a bit high but I don't drive it much on the highway and offroad top gear seldom gets used. Even when I take it to fraser the fuel cost savings would be minimal.

[Tonka_Tough]

ill shortly be putting a 12HT into my HJ47 troopy and i was going to be putting the 5 speed in it, how ever maybe an overdrive might be a better option to consider.

also if i read your post right then you already have done the engine swap is that correct? if so id love to know more about the swap and what you had to do exactly.