LSD (limited slip diff.) and gear ratios

[TurboMax]

**Info copied from mightyD50**

TYPES OF DIFFERENTIALS
All trucks 79-96 came with what Mitsubishi would call a 8inch differential in the rear

GEAR RATIOS
D50/MMs came with 3 different possible gearing options
3.545 used in certain 2wd trucks let you achieve optimal fuel mileage
3.909 most common gear ratio used in about our trucks most 4x4 came with them for sure
4.222 rarely seen in the D50/MMs only seen so far in 4x4s so far primarily seen in Dodge Raiders/Mitsubishi Monteros
4.625 never came in the trucks only seen in the Monteros/Raiders swaps into our housings

LIMITED SLIP DIFFERENTIALS & IDENTIFICATIONS OF THEM
LSDs or different gears can be swapped out of various vehicle depending upon wich diff you have if you have the 7.5in diff a rear diff
out of any FOUR CYLINDER MM/D50, Montero/Raider will work

If you have a LSD factory you will have an orange sticker in the door jam and on the differential housing its self talking about the use of LSD additive inside of that housing If you cant find those stickers but still wanting to make sure you do or dont have an LSD you can jack the back of your truck up and spin one wheel then watch the other side to see if it spins in the same direction

Now if you have a 4x4 MM/D50 the rear differential out of a Starion/Conquest will work Starions 1983-1987 (1986/87 widebodies all came LSD, narrowbodies with LSD are more rare) used a 7.5" diff, which will work in the FRONT of a 4cyl truck/rig. Starions 1988-1989 used a 8.0" diff, which will work in the FRONT of a V6 truck/rig. (thanks Robert) If you have a V6 powered truck any first gen Montero/Raider with a V6 will change differentials with your trucks 2nd generation Monteros wont work with the 8in housing available in our trucks I was told the Monteros have a high pinion design compared to the trucks low pinion design

---keRby
mopar_1986_power_ram50


The Starion LSD from years 83-87 will fit the front diff of the 4cyl MM/D50 trucks/Monteros.
The Starion LSD from years 88-89 will fit the front diff of the 6Cyl MM/D50 trucks/Monteros.

The Montero LSD from 83-89 4Cyl will fit the 4cyl MM/D50 trucks rear diff.
The Montero LSD from 89-91 6Cyl will fit the 6cyl MM/D50 trucks rear diff.

Not all early Starions had LSD, special order and 85.5.
All widebody Starions had LSD.
Not all Montero's had LSD, check for orange sticker inside drivers door jamb.

Kane
MainstreaM


just to clerify no truck or monty has a 7.5" rear diff.only the front is a 7.5".the rear is a 8".the 4 banger monty and the v6 has a 8" rear for the gen 1.the early years 7.5" starion lsd can be swaped into the front 7.5" diff,with a spacer.

powerram50

[mxmikie]

all vans had 4.222 posi

[Spicoli]

Damnit, I wish I knew were I had posted or found that at but some of the 3000gts w/ 6spd ran a 8in the back that had like a 3.08 ratio.

[Chauron]

If you have a LSD factory you will have an orange sticker in the door jam and on the differential housing its self talking about the use of LSD additive inside of that housing If you cant find those stickers but still wanting to make sure you do or dont have an LSD you can jack the back of your truck up and spin one wheel then watch the other side to see if it spins in the same direction

So if both wheels spin the same direction then its a factory LSD?

[Spicoli]

Yes, all of em should have a lil orange sticker on em some were talking about it. Unless a PO put it in.

[pennyman1]

What if you jack up the rear and spin one but the other one doesn't move either direction? the one in my 80 D-50 does this, and when i side step the clutch, both tires spin.

[79D50]

This is very good, clear and concise information. Thanks for that! I am going JY hunting next week. I will be looking for a '83-'89 4 cylinder Mitsu Montero. Aside from making sure the rear diff is 8" (assuming my '79 D50 rear diff is also 8" - will measure tonight) is there anything else I need to pull? Do I just need the gear pack out of the pumpkin or do I need axles etc? Please advise. Admittedly, I am not very knowledgeable about this end of our trucks.

Thanks -- Paul

[TurboMax]

This is very good, clear and concise information. Thanks for that! I am going JY hunting next week. I will be looking for a '83-'89 4 cylinder Mitsu Montero. Aside from making sure the rear diff is 8" (assuming my '79 D50 rear diff is also 8" - will measure tonight) is there anything else I need to pull? Do I just need the gear pack out of the pumpkin or do I need axles etc? Please advise. Admittedly, I am not very knowledgeable about this end of our trucks.

Thanks -- Paul

Just pull the whole third member out. It will bolt to your existing axle housing. You may need to swap out ring gear and pinion if its the right gear ratio your looking for.

[Spicoli]

Just the carrier out of the raider/montero. Axles are different legnths (d50 is wider) so youd have to get the whole housing. To make the diff axles work. If you cant find a 4cyl the V6 ones ran a 8in front diff but had a 28spline count vs the 31 thats on the rear (i think thats the right spline count.)

Most likely, the monteros diff will have 4.625s or 4.22s depending upon what you want for gears swap is possible.

BTW big shout out to Walter for this smilie YAY

[79D50]

So if I am hearing you guys right, I just need to pull the cover off the diff in the junkyard and yank out the guts of the pumpkin (entire third member) and that's it. My rearend is 8" @ 3.9.09. You guys know my build (built for low/mid range power) is the 3.9 the best gearing?