Outer Limits 4x4 Board

I'm installing a Isuzu 6BD1 with 6speed Isuzu gearbox into a 63 Jeep J200, I already own a GQ transfercase which would require divorcing. Does anybody know if it'll handle a 6BD1 which will be turboed later?
The other option I'm considering is the Land Rover LT230. I don't own one though they seem common and reasonably priced.
Front diff pumpkin is drivers side though if I came across the right front diff (eg.Dana60) & Tcase option at the right price I'd happily upgrade from the Dana44.

Advanced Adapters(Atlas manufacturers) beleive the LT230 is good for 1000hp while the centre diff is locked. But do you want Constant 4wd? A part time conversion is possible though. No idea on how this compares to a nissan T case.

You realise the Isuzu 6 speed has no overdrive? It is 1-1 in 6th.

I have no idea about the nissans but the lt230 is available in a few different ratios high and all 1 ratio low, there are low range after market gears available...

I really like the constant 4wd set up and selectable center locker....very handy to be able to use 4 low on the road with out wind up

Serg

I personally would run the Nissan case no worries, its free.

You dont need to run it divorced. You can make your own adapter to mate the GQ to the gearbox, it lends itself to it really well.

There is pictures of my one adapted in the Members section. I also did one for my brother.

The LT230 is a stout case, but they can be expensive.

The GQ one is cheap and strong (chain drive though, seven rows)

Either way, post pictures of what you have there so we can see.

Have seen a GU one behind a 550ish RWHP duramax and its still goin strong, should be fine behind the 6B

RUFF wrote:You realise the Isuzu 6 speed has no overdrive? It is 1-1 in 6th.

Isuzu have a lot of 6 speeds, many are overdrive. Has this one been checked for model code or counting input/output turns?

Thanks for the input everyone.
The 6speed is an overdrive and I have a 5speed non overdrive spare that came with the motor.
I had a feeling the Nissan case was plenty strong but thanks for removing the niggling doubt. I hadn't considered adapting it instead of divorcing. What's the process of adapting?

Orrrr for a reasonable price I can get a lt230 from a 97 Disco, Ratio I believe is 1.2:1 Are all diffs/vehicles suitable for full time 4x4 or would I have to convert it to part time?
The overdrive from high range of 1.2:1 might just save me from changing diff ratios though I'm not sure what they are so I'll check that out next. Tyres will be 33's.
Another plus for the lt230 is the PTO

RUFF wrote:Advanced Adapters(Atlas manufacturers) beleive the LT230 is good for 1000hp while the centre diff is locked. But do you want Constant 4wd? A part time conversion is possible though. No idea on how this compares to a nissan T case.

You realise the Isuzu 6 speed has no overdrive? It is 1-1 in 6th.

I fitted an Isuzu 6 speed gearbox (MXA-6R) in my Land Rover, and both 5th and 6th gears are overdrive ratios (4th is direct). I know of another Isuzu 6 speed gearbox (MBP-6P) with 5th direct and 6th overdrive.

Perhaps with the 6 cylinder engine, or in their heavier trucks, Isuzu don't use overdrive gearboxes - this is far beyond my limited knowledge.

Jeepo wrote:Thanks for the input everyone.
The 6speed is an overdrive and I have a 5speed non overdrive spare that came with the motor.
I had a feeling the Nissan case was plenty strong but thanks for removing the niggling doubt. I hadn't considered adapting it instead of divorcing. What's the process of adapting?

Orrrr for a reasonable price I can get a lt230 from a 97 Disco, Ratio I believe is 1.2:1 Are all diffs/vehicles suitable for full time 4x4 or would I have to convert it to part time?
The overdrive from high range of 1.2:1 might just save me from changing diff ratios though I'm not sure what they are so I'll check that out next. Tyres will be 33's.
Another plus for the lt230 is the PTO

A 97 Disco LT230 transfer case will have a 1.2:1 reduction (not overdrive) in high range. Defenders have 1.4:1 reduction, those 110's with the Isuzu engine and Santana gearbox had approx 1:1 (can't remember exact ratio) high range.

If you want to use a PTO, the Isuzu gearbox (at least those I know of) has a cover on the left side where the PTO bolts - several aftermarket PTO's will fit (try truck wreckers or aftermarket suppliers).

Jeepo wrote:Orrrr for a reasonable price I can get a lt230 from a 97 Disco, Ratio I believe is 1.2:1 Are all diffs/vehicles suitable for full time 4x4 or would I have to convert it to part time?

The overdrive from high range of 1.2:1 might just save me from changing diff ratios though I'm not sure what they are so I'll check that out next. Tyres will be 33's.

I think that is underdrive ie gear reduction, the opposite of overdrive. You probably need to have a close look at all your ratios including tyre size and work out your rpm at various road speeds to be sure you're happy. Try this calculator: http://members.optusnet.com.au/chimpboy ... ratios.xls" onclick="window.open(this.href);return false;

(You can add new gearboxes and transfer cases to the tables in the second and third tabs, it is a bit lacking in transfer cases unfortunately.)

Any unlocked diff can handle full time 4WD, the question is the transfer case. If there is no centre diff then it cannot handle full time 4WD as you will get wind-up in the transfer case due to differences between the distances travelled by the front and rear axles. For this reason I don't think the Patrol transfer could be used for full time 4WD.

to give you an idea of ratios on the rovers...all diffs running the lt230 are 3.54-1

Serg

Bush65 wrote: A 97 Disco LT230 transfer case will have a 1.2:1 reduction (not overdrive) in high range. Defenders have 1.4:1 reduction, those 110's with the Isuzu engine and Santana gearbox had approx 1:1 (can't remember exact ratio) high range.

If you want to use a PTO, the Isuzu gearbox (at least those I know of) has a cover on the left side where the PTO bolts - several aftermarket PTO's will fit (try truck wreckers or aftermarket suppliers).

Thanks, I've got it now, 1.2 turns at the input is 1 turn at the output, so a 1.2:1 is underdrive. So I'm now looking for a 1:1
The tag on my 6 speed is unreadable but 5th is direct and 6th is an overdrive.
Your right about the Isuzu gearbox having a pto on passenger side. Another option.

just remember with the isuzu it's not the power you have to wory about its the torque pulse they have

hillbilliywheelchair wrote:just remember with the isuzu it's not the power you have to wory about its the torque pulse they have

Exactly why I'm asking around. I started out thinking the 4speed cruiser box and transfer that was in the Jeep would be plenty. I've seen em handle plenty of HP.

Also thanks Serg n Chimpboy for the ratio advice, I'll have to look at the diff ratios. I only get home on weekends at the moment.

This is the gq transfer I already have. I think it had a 3l petrol motor.
I'm thinking the gearbox shaft in the above pictures could be cut and a flange welded onto it, a small tailshaft between transfer and gearbox could then bolt to the flange. Would the small piece of gearbox shaft and flange need to be held into place? They can't exactly move once the transfer is mounted securely.

This is the first attempt, the firewall has since been cut so the motor sits further back, this allowed the sump to clear the diff.

Remember when nearly all bullbars looked like this?

This pic shows a similar method to what you are proposing using an LT230 transfer case. It gave good service.

Cool thanks evryone.

I saw that gearbox shaft and went, yep!

Here is mine:

Here is my build thread:

http://www.outerlimits4x4.com/viewtopic ... 22&start=0" onclick="window.open(this.href);return false;

Jeepo wrote:Thanks for the input everyone.
The 6speed is an overdrive and I have a 5speed non overdrive spare that came with the motor.
I had a feeling the Nissan case was plenty strong but thanks for removing the niggling doubt. I hadn't considered adapting it instead of divorcing. What's the process of adapting?

Orrrr for a reasonable price I can get a lt230 from a 97 Disco, Ratio I believe is 1.2:1 Are all diffs/vehicles suitable for full time 4x4 or would I have to convert it to part time?
The overdrive from high range of 1.2:1 might just save me from changing diff ratios though I'm not sure what they are so I'll check that out next. Tyres will be 33's.
Another plus for the lt230 is the PTO

I forgot to mention the LT230 is a good option too. Lots of ratios available, 3.3:1 stock, and can be adapted fairly easily too.

bj on roids wrote:

Jeepo wrote:Thanks for the input everyone.
The 6speed is an overdrive and I have a 5speed non overdrive spare that came with the motor.
I had a feeling the Nissan case was plenty strong but thanks for removing the niggling doubt. I hadn't considered adapting it instead of divorcing. What's the process of adapting?

Orrrr for a reasonable price I can get a lt230 from a 97 Disco, Ratio I believe is 1.2:1 Are all diffs/vehicles suitable for full time 4x4 or would I have to convert it to part time?
The overdrive from high range of 1.2:1 might just save me from changing diff ratios though I'm not sure what they are so I'll check that out next. Tyres will be 33's.
Another plus for the lt230 is the PTO

I forgot to mention the LT230 is a good option too. Lots of ratios available, 3.3:1 stock, and can be adapted fairly easily too.

The reason I never used it, is becuase I needed a centred rear output.