HJ61 12H-T mods

I dunno how much diffs are worth but I am guessing around 1500 each = 3 grand.
That is alot of fuel you would have to save. And if you go offroad much the higher gearing will be a pain especially in low range where th 60s have a 2/1 transfer case ratio. Running bigger 15 inch tyres could well negate any fuel savings due to their larger width. best option for purely fuel saving would be 235x16 inch tyres
Personally I reckon whatever you try will be alot of cash to spend on a 10 grand 4by to alter what is a pretty good setup to start with

My experience with my HJ61 to improve the economy is stay around 95kph.
5 or 10 minutes longer to get there, but saves a lot on fuel. I would agree with Davoe, and how easy to get the tyres if you bust one in the bush?
Dave

Mate. After running "small" tyres on my petrol 60 series I went to 33 x 10.5 R15 BFG AT's.

Better fuel economy? I didn't check but I doubt it.

Lower RPM on the highway? Yeah, a bit, but speedo was out of whack which cuased my photo to be taken, twice!!! (both on long weekends-double demerits)

Better off road? You bet ya! What I lost in torque (bugger all) was more than made up for by the easier driving in sand, rough roads, rocky stuff.

More proof that the height of the tyre plays a bigger role when off road than the width.

thanks for responding guys
this is how i figure it
the hj61 is in pretty good shape - inside and out - for a 20 year old vehicle - mechanical seems ok and it's very straight, neat and tidy with 240000kms on the clock - cost $8,500 - we got it for it's size - can seat 8 and tows the camper ok - we want it mainly for the highway - between adelaide and sa's west coast - will do very little off road - maybe a run along a beach or dunes and a bit of dirt a couple of times a year - i can spend a grand on an exhaust, a grand on an intercooler, 1500 to get BOTH diffs done and another 1500 on some 33" tyres - so thats 5 grand plus the 8.5 purchase cost makes it $13,500 and it should hum on the highway, pulling the camper and last another 20 years - so i am just doing the homework at this stage - thanks again for your replies/knowledge/advice - much appreciated

Marks adapters sell transfer gears that are higher on the highway and lower in low range....might be the go, cheaper than diffs, but in all fairness, you are chasing yout tail with economy.....8km/l is about right. the cruiser weighs 2 tonnes off the factory floor, and you probably have bars and suspensionlift on it aswell...Bigger tyres will help your revs/100kms and probably make it cruise easier, but the braking performance will suffer thesame % as the revs drop....and the 12ht doesnt mind the revs....you could intercool it....but you would get more power out of it then, and want to use it....lol
Life is a compromise......gr8 truck
Andrew

G'day jelm,
Rather than me writing it all again, I hate typing, it might be easier if you read thread 32059.

Avagoodn
Pezza