Introduction
It is no secret that the L300 Delica has frustratingly short final drive gearing of 1:4.875. This paired with the OEM tire size (28″ equivalent diameter) makes for frustratingly high RPM on US highways.
The reason the gearing is like this is due to the lack of power in both the gas and diesel engines that came in these vehicles. Gearing could be taller for flat highway driving, but the steep grades are the real kicker.
Some of this can be overcome with performance and cooling modifications to the engines, but you are still stuck with that short gearing, especially with the manual transmission, which has a shorter top gear compared to the automatic.
Increasing tire size is the easiest way to drop those highway RPMs, but that also has its limitations. Big tires can easily be fit if you are comfortable cutting and chopping up the front fenders. The caveat is that bigger tires have a bunch of negative impacts.
- Increased weight, reducing performance
- Decreased braking performance, not great
- Lower fuel economy
- Increased stress on axles, namely CVs
So there is a clear reason why re-gearing can be beneficial under the right circumstances. Make no mistake, gears can be expensive and a pain to install, but if you are planning a locker or LSD install you can kill two birds with one stone in terms of the installation labor. If you have the patience and are good at finding things on the internet, then you can find used gears for a fraction of the cost as new. Mitsubishi gears from this era are also of impeccable quality and strength. I’ve pulled gears that have over 150K miles on them and they still look new!
Background
We must first understand what the Delica has and what is compatible. The 4wd L300 has a large size 8″ rear differential and a smaller 7.25″ front differential. Most of these vehicles came with a short 1:4.875 ratio (this information is stamped on the interior VIN plate). Some others came in the slightly taller 1:4.625 ratio, which seems to be very uncommon. The small front differential is the biggest limiting factor for re-gearing, as the smaller 7.25″ front differential had fewer gear options. Below is a list of gearing options:
- 1:4.875- Available in both 8″ and 7.25″ (most common ratio)
- 1:4.625- Available in both 8″ and 7.25″
- 1:4.222- Available in only 8″
- 1:5.285- Available in both 8″ and 7.25″
- 1:5.9- Available in only 8″ (Super rare, from Hyundai)
So its clear that the only options for the stock differentials are 1:5.285, 1:4.875 and 1:4.625, and 1:4.625 is not much taller than the original 1:4.875.
To get around this constraint an 8″ front differential can be swapped in place of the smaller front 7.25″ unit. Using an 8″ front differential also has more locker options, discussed later. Some of the 1st generation (1987-1990) Montero/Pajeo came with this large size differential. This means that both front and rear diffs will take the same 8″ gear kit. These vehicles came with low pinion (LP) front differentials, later model front differentials are all high pinion and do not fit the L300 Delica. Below are the known vehicles with Delica front differential compatibility:
- Gen 1 Montero/Pajero SWB 3.0 V6- 8″ front differential, LP
- Gen 1 Montero/Pajero LWB 3.0 V6- 8″ front differential, LP
- Gen 1 Montero/Pajero SWB 2.4 I4- 7.25″ front differential, LP
- Gen 1 Montero/Pajero SWB 2.5 diesel- 7.25″ front differential, LP
- Gen 1 Dodge Raider SWB 2.4 I4- 7.25″ front differential, LP
- Gen 1 & 2 Hyundai Galloper LWB- 7.25″ front differential, LP
- Gen 1 & 2 Hyundai Galloper SWB- 7.25″ front differential, LP
Another point of difference is CV axle spline count. All 8″ differentials had 28 splines. 7.25″ front differentials came in both 25 spline and 28 spline configurations, generally the manual transmission cars got the bigger 28 Spline CV axles, but there are exceptions, so there are no guarantees. It’s always best to check VINs and pull PNs to be sure.
Note: The automatic trans Delica L300 has 25 spline CV axles and the manual trans has 28 splines.
Below are the differences between the larger and smaller differential housings. You may notice the top of the differential has a “KN2” or “KN3″ stamped on it. This means nothing, as I have seen both numbers on both size housings. The most notable difference is the casting for the oil channel. The larger 8” unit has an oil channel that wraps around the side.
Beware, There are Mitsubishi and Hyundai differentials with the same sideways oil channel configuration in the small 7.25″ size, so just because it looks right does not mean it is the larger 8″ size! These are less common and found in the L200 Pickup Truck and Hyundai Galloper (maybe others).
If you want to upgrade to an 8″ differential, it’s best to source the whole axle assembly to ensure the axles and intermediate shaft all work. It will probably also be a lot cheaper than sourcing individual parts as well (the intermediate shaft alone is $600 new). We were able to source the whole assembly from a junkyard for $700 shipped. It came with the 1:4.625 ratio gears.
Our Build
With the Cummins R2.8 Engine Swap we have plenty of power and no need for the high RPMs on the highway. RPMs are still higher than necessary with the 31″ tires we run. For this reason we are swapping in the taller 1:4.222 ratio gears. This in turn is the reason for swapping in the larger 8″ Montero differential, as the 1:4.222 ratio gears only came in the larger 8″ size.
The 8″ Montero front differential axle spline count is 28, instead of the smaller 25 that came on our automatic Delica. So the Montero CV axles will replace the original Delica CV axles. These 28 Spline axles are also bigger and stronger all around, so a good pairing for the R2.8.
The PN for this 1:4.222 gear kit is MB185462, superseded by MB527151. This ratio came in a handful of USDM cars and some later model vehicles overseas.
Below are PNs for some of the other low pinion gear kits:
- 8″, 1:4.875- MB527147
- 8″, 1:4.625- MB527150
- 8″, 1:4.222- MB185462
- 8″, 1:5.285- MB241981
- 7.25″, 1:4.625- MB527750
- 7.25″, 1:4.875- MB185456
- 7.25″, 1:5.285 – MB527152
for the rear, we got super lucky and found this new old stock late model (2006-2015) L200 Triton complete rear differential assembly with LSD (PN: MN107698) on eBay for only $400 Shipped. I’m not sure why this non-USDM Part was in the US, but it worked out!
This was a great find and saved the build around $1400, as the original plan was to buy a 1:4.222 gear kit ($700) and an air locker ($1000), plus new bearings and seals.
Unfortunately the new LSD was missing the thrust blocks, so they had to be swapped over from the original differential. This meant that the differential needed to be rebuilt.
For full rear diff rebuild details, see video below:
https://www.youtube.com/watch?v=Pqr46ZtcYFM
The final piece to the Puzzle was finding a 1:4.222 gear kit to put in the Montero 8″ front differential. We once again got lucky and found a junkyard with with a rear axle that contained the 1:4.222 gear ratio; it was $350 shipped. This came out of a 1988 Mitsubishi Van Wagon, The Delica’s USDM cousin. We ran the VIN to confirm the ratio.
Lockers
There are several lockers that fit the 8″ & 7.25″ diffs:
- ARB Air Locker RD210, Rear 8″
- ARB Air Locker RD110, Front 8″
- TRE Air Locker TR309, Front 7.25″, 25 spline auto trans
- TRE Air Locker TR311, Front 7.25″, 28 spline manual trans
- TRE Air Locker TR210, Rear 8″
- TRE Air Locker TR110, Front 8″
- TRE E-Locker TE210, Rear 8″
- TRE E-Locker, TE110, Front 8″
- Harrop E-locker 34551, Rear 8″
- Lunchboxes and crab lockers excluded from this list
We chose the TRE TE110 for the front. TRE is a Chinese clone of ARB/Eaton, but they have a proven track record for robustness and reliability in the Montero community, and at a great price. This locker will also see very little use for our application, since we have an LSD in the rear. The E locker also means there no need for an air compressor and pneumatic controls.
TRE is also the only manufacturer that makes a locker for the smaller 7.25″ OEM front differential.
The 8″ Montero front differential was fully rebuilt during the locker install. We replaced all the seals and bought OE shim kits for the locker. The original pinion bearings from the Montero differential were reused as they were in great shape. This allows the spacer tube and existing shim to be swapped over onto the new 1:4.222 ratio pinion shaft. This should theoretically get it really close to Spec, without needing to start shimming from scratch.
Check out our full front diff build video here:
https://www.youtube.com/watch?v=tWEfy8oXtBs
Next the differential side mounting tab needs to be cut off on order to fit it to the Delica subframe.
The new 8″ differential with locker can now be assembled onto the Delica subframe using the original intermediate shaft housing. This preserves the front bushing bracket, which the Montero does not have. The larger 28 spline intermediate shaft from the Montero fits right into the original Delica shaft housing.
Finally the Montero axles will need some modifications. The Boot guards will need to be removed in order for the larger axles to clear the bump on the LCA for the lower ball joint.
The bronze Delica hub thrust washers were swapped over from the original axles to the Montero axles with some fresh grease. These washers did not come on Monteros as far as I know.
The van is now fully re-geared with 1:4.222 gears. Ive been observing about 24-28 MPG highway with this taller ratio, a noticeable improvement over the 1:4.875 ratio. Cruising RPM is now around 2100 at 65 MPH with 31 in tires, in contrast to 2500RPM with the shorter gears.
