Thread: Auto behind the 4BD1

Originally Posted by Corgie Carrier

I have been reading heaps of threads about the problems of putting a ZF behind the 4BD1.

What about the 727/lt230 or even the C4/lt230 combo, that came out in early Rangies. Would these autos hold up to torque of the Isuzu?

Neale

Yes, but with a very limited rev range and a limited spread of ratio's, I think it would suck lots

Oh, the 727 came with LT230, the C4 with a cut down LT95

In what way would it suck?

Are the ratios too far apart?

What about for a pure bush truck?

I was thinking about building a truck for crawling around the high country, I don't travel very fast.

Thanks for the info on the transfer cases on the autos.

Neale

Overview

I saw that web site, that's what got me looking at the different autos that LR used as standard.

The problem with those kits is that they are for gm autos, I then have to spend $1k to get an adapter kit from Marks to fit an LT230 to it.

If I use a C4 or 727, they already have a LR transfer case on them.

Does anyone know how different the bolt pattern is for the 727 or C4 to the GM autos?

Neale

Spk to Justin Cooper (moderator) in Hobart. He is quite adept at fitting and destroying his own.

Originally Posted by Corgie Carrier

In what way would it suck?

Are the ratios too far apart?

What about for a pure bush truck?

I was thinking about building a truck for crawling around the high country, I don't travel very fast.

Thanks for the info on the transfer cases on the autos.

Neale

With an engine that's governed awfully low, 32-3600rpms, you'll find it very limited with only 3 gears, especially without convertor lockup, as in, it will struggle to power through enough to obtain the next gear, under load, you'll find yourself foot to the floor on the governor, lift the throttle, upchange, then foot it only to kickdown again, I'd be using a 4 speed auto

Originally Posted by rovercare

With an engine that's governed awfully low, 32-3600rpms, you'll find it very limited with only 3 gears, especially without convertor lockup, as in, it will struggle to power through enough to obtain the next gear, under load, you'll find yourself foot to the floor on the governor, lift the throttle, upchange, then foot it only to kickdown again, I'd be using a 4 speed auto

Ahh the old Merc diesel trick. On the boards, back off to let it change, back on the boards.

What exactly about the Isuzu wrecks a ZF? If you had the engine tuned on an engine dyno to produce say 350Nm, surely a D1 300Tdi auto (like mine) would be an ideal candidate and a fairly easy swap.

Would it be a waste of effort for 350Nm? That would at least put a D1 on par with a LC 80.

Originally Posted by B92 8NW

Ahh the old Merc diesel trick. On the boards, back off to let it change, back on the boards.

What exactly about the Isuzu wrecks a ZF? If you had the engine tuned on an engine dyno to produce say 350Nm, surely a D1 300Tdi auto (like mine) would be an ideal candidate and a fairly easy swap.

Would it be a waste of effort for 350Nm? That would at least put a D1 on par with a LC 80.

Torque pulses, and the ability of the 4BD1 to produce mountains of Torque at very low revs, where the ZF is low on line pressure, thereby tearing the clutch packs, and torque converter lock up clutch to bits.

The last trans I had made/ modded used a low stall converter, a very heavy duty lock up clutch and beefed up front pack, and IT lasted less than 10,000km. The problem was also finding the shift points and ideal governor weight to enable proper shifting without holding on to gears until fuel governor is reached. The best option but quite expensive, is to utilise a 4HP24E and converter (Huge lock up clutch) from a P38a, and use a Compushift shift computer to electronically shift the trans. These units are programmable and very versatile. IF I was to go back down the auto route, (I still have the adapters etc) this is the way I would go.

JC