Landcruiser Overdrive

Go the straight 5 speed, less hassles, and change the diff ratio.

I had a 307 Chev in my fj40 with no issues at all with the 4 speed manual. I ran 31x10.5x15 tyres and the standard 4.1 ratio diff. The only problem was it ran hot, so I had a custom radiator made - 5 core, never got hot again even hard going on the beach.

If you can source the 3.9 centres from an early 3 speed fj40 - 1973 model – these will give a slightly better highway feel. 1974 fj40 came with the 4 speed, 1984 fj40 came with the 5 speed or late 1982 fj60 5 speed box.

Don’t forget the 4 speed auto from a VN / VP series Commodore – fully manual with no electronics.

As with any conversion do your homework on costings and approvals – you would have already dome some anyway by having to upgrade the front brakes to discs with the V8 conversion.

If it were me I’d go the V8 auto with 3.9 centres.

Gday
Id be carefully considering what to do too....the cruiser 5 speed drops revs by 500 rpm...hardly enough to worry if you have to spend heaps....however, if you need a rebuild, then it would probably be cheapest to find a 42 series with 5 speed....or shafts from a 42 and a 60 series 5 speed....yopu dont mention if the 40 has the later 4 speed with split transfer or the earlier 4 speed with 55 series transfer... the later will eventually blow up.
Are your rear axles full floating??? (do they have that long hub with 6 bolts in the centre of the wheel studs)
When it comes to buying parts, you are heaps better off going to pickles.com and getting a wreck with what you want in it....
Also check out ebay.com.au
Andrew

Hi if you are interested I have a BJ40 with 3.8V6 and a VP TH700 auto for sale conversion has bugger all miles on it but the motor threw a rod. The T/case is recod. Complete exept for D/S door handle, front drive shaft, battery and 3 windows out of late canopy. I had it on Ebay item 4597112592 but no bids. It finished a couple of hours ago so it should let you see pics if you put in the item #

Regards
Tour Boy

Hi

Had a similar problem myself a few years ago when I converted the 60 series to 350 chev and Turbo 400 which has no overdrive, mainly built as a tourer to tow. After evaluating several alternatives I fitted 35" tyres which gave me 2300 revs at 100kph.
I also have a set of 33" tyres for around town use. Works for me.

Thanks for your replies all. Some sound advice. Does this mean that no-one employs a fourspeed with an aftermarket overdrive?
It sounds as though all have gone with 5 speeds, or diff/wheel ratios....
This does surprise me somewhat, as the gearmaster overdrive is a 0.77 ration decreasing engine revs by 23%. Further to that, it is a completely sepearate mechanical unit and as such can be removed/replaced/overhauled independantly of the rest of the gearbox/trannie setup...
In case I dont get another reply up before Sunday. Merry Christmas to all!

I have a HJ47 and had the same problem with achieving decend highway speed without the "747 on take-off" type noises that the 2H makes at 90-100km/h.
I left the 4 speed in place as fitting a 5 speed is a lot more involved than simply fitting the box. Instead I fitted 3.5:1 diff gears, (not 3.7:1 which is common),This has the added benifit of making 1st gear more usable, (taller) and on comparison with a 1hz powered 5 speed cruiser results in the 4 speed showing only about 100rpm more at 90 km/h.
Interestingly, during this comparison I was stunned to find that in a "drag race" from standstill the 2H was able to keep up with the 1hz, the 1hz only pulling away at the top end of 4th but lost the advantage once it changed into 5th at around 80km/h. The 1hz was shifting slightly more weight but I would`nt have thought the speed difference to be so small.