Isuzu MSA Gearbox to LT230

Quote:

---

Originally Posted by Lotz-A-Landies

[*]Which model Isuzu box would be appropriate for my 3 ton demon of biblical proportions?

---

Any of the MSA series boxes will work fine. There are ratio variations where the MSA-5P (used from 85) has a lower ratio 3rd gear than the MSA-5G which I found in a 92 NPR250.

There is an MSA-5R which is slightly higher geared (5:1 1st and taller OD) but I haven't found which truck these are out of.
The MXA series are updated versions with lighter housings, interfaces should be the same and gear ratios follow the same suffix as the MSA.


Then you're into the 6 speeds.

Quote:

---

Originally Posted by Dougal

Any of the MSA series boxes will work fine. There are ratio variations where the MSA-5P (used from 85) has a lower ratio 3rd gear than the MSA-5G which I found in a 92 NPR250.

There is an MSA-5R which is slightly higher geared (5:1 1st and taller OD) but I haven't found which truck these are out of.
The MXA series are updated versions with lighter housings, interfaces should be the same and gear ratios follow the same suffix as the MSA.


Then you're into the 6 speeds.

---

I thought the 6-speed will interfere with the front prop unless you run a divorced t-case?

Quote:

---

Originally Posted by isuzurover

I thought the 6-speed will interfere with the front prop unless you run a divorced t-case?

---

I think I could make it fit. It doesn't appear any fatter than my 5 speed, just longer and the extension doesn't have any lumps in the wrong places.

Quote:

---

Originally Posted by the_grubb

Hey Lotz-A-Landies,
<snip>
Let me get back to you on this one when I have a bit of time to digest your ratios, weights and purpose....
<snip>
Of course. I have a complete cable shift here from an NPR truck which would be perfect for your application given the distance between driver and gearbox.

---

I'm gong to have to digest this info too.

May I say that the frontal area of Gog has the aerodynamics of a barn, so wind resistance is an issue. The one good thing is that I have already converted the ENV front-end from uni-joint to CV swivels so the constant 4WD will not be a problem.

https://www.aulro.com/afvb/images/im...010/10/266.jpg

I do have a spread-sheet on Series and R380/LT230 ratios, complete with revs/Km etc. I can send it tonight if you like.

Would most definitely be interested in the cable shift, save me looking for one! :)

Diana, put a turbo on your 4BD1 and you will be able to cruise at whatever (legal) speed you wish.

Something around a 3:1 to 4:1 final drive ratio in top gear should work well for you IMHO. It is easy to change ratios in the LT230 (or change LT230s).

Quote:

---

Originally Posted by isuzurover

Diana, put a turbo on your 4BD1 and you will be able to cruise at whatever (legal) speed you wish.

Something around a 3:1 to 4:1 final drive ratio in top gear should work well for you IMHO. It is easy to change ratios in the LT230 (or change LT230s).

---

Ben

Yes have thought about the turbo for the 4BD1 but thought I'd do the NA conversion and get it registered first. In regards to the mounting, I can't use the OEM turbo manifold or plumbing because it hangs over the top of the chassis rail right where the SIIB upper chassis/cab support is located. Have however thought about remote mounting the turbo above the gearbox bellhousing where the air cleaner is on most 4BD1 countys. The problem will then be if I wish to add an intercooler.

Not sure that I want to 110 plus KPH, in a 3m high 110 Land Rover! :eek:

I already have both a county 1.41:1 LT230 (2) and also a D1 1.222:1 LT230.

Diana

For those asking/interested.

Adaptor ring to mate the Isuzu gearbox up to the landrover flywheel housing.

With the landrover flywheel housing the distance from the back of the engine to the gearbox mounting face is 80mm and has the wrong bolt pattern to fit a Isuzu gearbox.

The Isuzu flywheel housing is 105mm.

The adaptor ring is 25mm thick, bringing the mating face up to 105mm and gives the correct bolt pattern to bolt up the Isuzu gearbox.

The Isuzu clutch slave cylinder is external to the gear box and originally I planned the design to not have to grind the landrover flywheel housing. However due to simplicity and finding that the Isuzu flywheel housing and starter fitted with no modification as an option, then the design was changed.

Mounts for external clutch slave cylinder. (You use the original LT85 slave cylinder - it bolts straight up).

Attachment 30508


Adaptor ring bolted up to landrover flywheel housing. The pink bit down near the oil filter is what needs grinding to clear the clutch slave cylinder.

Attachment 30506


and a closer shot of where needs grinding. (ignore the oil filter - this is a truck motor).

Attachment 30507

Quote:

---

Originally Posted by Lotz-A-Landies

Ben

Yes have thought about the turbo for the 4BD1 but thought I'd do the NA conversion and get it registered first. In regards to the mounting, I can't use the OEM turbo manifold or plumbing because it hangs over the top of the chassis rail right where the SIIB upper chassis/cab support is located. Have however thought about remote mounting the turbo above the gearbox bellhousing where the air cleaner is on most 4BD1 countys. The problem will then be if I wish to add an intercooler.

Not sure that I want to 110 plus KPH, in a 3m high 110 Land Rover! :eek:

I already have both a county 1.41:1 LT230 (2) and also a D1 1.222:1 LT230.

Diana

---

Hey Diana,

With your 4.7 diffs and tyre diameter, if you do put a turbo on I would definitely go for a MSA-5G with a 1.003 Transfer Case. As Ben mentioned, this puts your final gear ratio at 3.6. Would just about go this way without a turbo too...

Otherwise given you already have a 1.22 TC, I would use a MSA-5R for your top speed gearing. Putting final drive ratio at 4.2 As Dougal mentioned, your first gear won't be as low as the 5G (but still 36% lower than the LT85).

Well this website Landrover: Isuzu 4BD1 Transmission - Home, although still a work in progress, has prices, installation procedure (downloadable PDF) and hopefully any other information anyone is looking for regarding this adaptor....


I would like to give a big thanks to GarrySeries3, if it wasn't for his kick in the pants to get his done, which meant I had to get mine done first... then I would probably still be in Bali surfing.....


PS the pictures in the manaul of the Gear Selector installation are from Riverrats build up - should be ready to ship up to you early next week mate!

Great idea and thanks for going into production! :)

What you haven't included is a price for the adapter and shaft for the Isuzu-LT230 without the Defender selector mechanism (as we discussed in an earlier post).

Diana