Replacement Axle Housings / Diffs / Drivetrain

[CMorris]

I know of exactly one vehicle in the USA with one. Dan Rao's truck has it and it is impressive. Whether you could ever find one or not, I wouldn't plan around that.[/QUOTE]

Make that two..............I have one on my '63 IIA 109 pickup.......sourced for me by Rovers North.

[TeriAnn]

You guys still at this? It has been a while since I looked at this thread. But finally we have a usage note.

Thank you all for the responses, they are very helpful. Let me outline some of my own input to help.

- Usage - It'll be used for trail / basic off-road driving mostly in the Texas Hill country area. (Hills are a relative term in Texas). I do not want to nor intend to rock crawl or do anything insane. I do want more power and an overdrive. Those are the bare requirements - I'm just not sure how to get there (reasonably). Camping, ski trips, and long stretches of road broken up by trails.

- Transmissions - I have just read good things about the NV4500, but understand the first gear is really steep - hence the question about gearing down to 3.54 to mitigate it. The NV3550 I'm not as well-versed on. Back to the books on that.

A gearbox with a granny first should not be in a drive train that has a transfercase unless you are building a gonzo rock crawler. Which you are not. Best to stay away from any set of gears that include a granny low. You will never use the gear. Consider the granny first to be dead weight.

You should be thinking close range 4 or 5 speed top loader box.

Combos:
* SBC 350 - > NV4500 -> Series T-Case (ok, maybe just my idea)
* 3.9L Rover -> R380 -> LT230
* GM 4.3L V6 -> NV3550 -> Series T-Case
* Other proven combos I'm missing that are easily sourced in USA? (2.25L is not an option)

The Chevy 350 is a very good engine for this kind of transplant. With the aluminum heads it is about 50 lbs heavier than the 2.25L petrol. Use the rams head exhaust manifolds. It is all stock off the shelf parts to the transfercase adapter. This is probably the easiest V8 swap. If the electronics don't scare you there are some folks using the new GM small block V8 engines and getting both power and very good fuel mileage.

The Ford 302/5.0 and 351 are good engines and you can use off the shelf Ford parts on back to the transfercase adapter. A 302/5.0 with aluminum head is about 50 lbs lighter than the 2.25L petrol. The early Bronco folks make engine mounts & oil pan to help this engine work in a LR engine bay.

3.9L Rover & R380 This combo is not as robust as the options above and parts are a lot more expensive. If you get a any of the Rover/Buick V8 engines get a recent rebuild that has top hat cylinder liners. These engines are not known for a long lifetime nor for high fuel mileage.

GM 4.3L. I don't know this engine. But look for something that will be under stressed and put out a lot of torque below 3000 RPM. Most high HP engines put their power out at higher RPMs and rob the low end to feed the high end. If you look at Edelbrock performance specs you should notice that their performance charts do not go below 3000 RPM. That is because a lot of the performance parts perform worse than factory stock at the low end. When I was head hunting the only head I was able to find that worked at the low end was Air Flow Research.

Anyway ... most off road driving is done well below 3000 RPM and V8s tend to get their best fuel mileage loafing around 2500 ish RPMs.

I suggest a small block V8, Ford or Chevy, with either stock or AFR small valve heads, and a truck towing cam. EFI will give you better fuel mileage. Keep compression 9:1 or lower and you can run regular.

Gearbox - NP-435 close ratio (Ford or Chevy) or SM420 close ratio (Chevy engine). Both are very robust 4 speed top loaders from full size pickups & SUVs. Again a granny first is redundant when you have a transfercase and is basically dead weight.

I suggest a stock transfercase, C suffix and newer because they have the more robust intermediate gear shaft & bearings and a Santana clone overdrive from Heystee automotive. This overdrive has been proven to handle 500+ HP.

Diffs & axles - The strongest stock solution are ENV axle assemblies. I think these came on front and rear on SIIA One Ton and also on the forward controls. If memory serves they were manufactured by Eaton. Second strongest Is the Salisbury which is a old style Dana 60 manufactured under contract from Dana. These were stock on the SIII One Ton front & rear. The Salisbury was also stock on the SIII 109. The Salisbury is way stronger than the standard Rover axle but it never hurts to upgrade the Salisbury diff and axles. Your common Salisbury diff upgrades are either an ARB air locker or a Detroit locker (automatic locker). Strengthened axles are available from ROAM Off Road or GBR (formally Great Basin Rovers). GBR can also provide hardened drive flanges and greasable spring bushings.

You will want to convert to power steering to get the steering box out of the way. The current hot set up uses a Range Rover P-38 steering box, pitman arm and lower steering column.

Fifteen or twenty years ago a V8 swap into a Series truck required a lot of custom engineering and custom fabrication. These swaps are common enough with small block Ford & Chevy engines that you can pretty much follow established patterns and end up with a reliable conversion. Advance Adapters has made the conversion almost off the shelf. The hardest part these days is reworking the bulkhead for bellhousing clearance and moving things over to centre the engine in the bay. You want to have good sheet metal welding skills if you intend o do the conversion yourself.