I'm doing lots of work to my old 94 12v and im gonna be lifting it and was wondering what gear ratio is best for a 5 inch lift, 2 inch leveling, 3 inch body with I hope to fit 39.5 Super Swamper TSL's on it but the tires will be no less then 38. Also im not sure if I have a open or Limited slip Diff cause my Mechanic confused me by saying if it was open the 1 back tire that would spin would be the passenger but its my drivers side. Is this true that open spins only the passenger side rear wheel? Thanks for any help given, >.>b

 

if only one tire is spinning, you have an open diff, normally the pass side will spin, but it will always be the tire with the least amount traction, so it could be either side, the only other possibilty is, you may have a lsd that is fried, but probably unlikely, my 98, i was able to clear 38.5 x 11 boggers on an 8in wide wheel with no rub, and that wae with a 4.5 lift, as far as gears go, i love my 3.73's with 35in tires, so a 4.10-4.56 might suit the 39's well, when i had the 38's i didnt use 5th gear very mutch, and if you have an auto trans the 4.56's would probably be your best bet to keep some stress off the trans

 

4.56's minimum if you want the truck to perform closely to stock. The size of the lift, level, etc., have no bearing on the gear you choose, it's all in reference to the tire size.

Your stock tires are only 31.5 and every 2" in tire height has the same effect as going numerically down one gear size.

If you had 3.73's on 31.5's and went up 7 - 8 inches in tire size, you'd effectively be changing your final drive ratio into the neighborhood of 3.15 - 3.22.

Bump the gears to 4.56's and you're back to what you had originally.

On my last truck, I went from stock tires to 36" TSL swampers and did 4.56 gears with ARB lockers in it. I had been contemplating 4.88 gears, but thought they be too deep. I was kicking myself for only going with the 4.56's.

 

Thanks for all the info, where would I be able to find 4.56 Gears online? I've looked around before and couldnt find much cause I'm really not 100% sure what to look for, thanks again.

 

Oh also do you need a LSD for lockers or can a Open diff have some aswell? Sorry for some of the dumb questions but this is my first truck I'm doing up for off road.

 

LSD, open, lockers, spools and selectables are all types of differentials and they are mutually exclusive.

Open is where you have no locking action at all. All the power goes to the wheel with the least traction.

Limited slip is where you have either clutches or gears in the differential and as one wheel slips they apply power to the wheel with traction. It's not always 100% reliable, especially in the clutch pack designs.

A locker allows differential action when NOT under power, but when power is applied it will lock both wheels for 100% traction.

A spool is not really a differential at all. It solidly locks both axle shafts together and DOES NOT allow either wheel to spin at different speeds. Power is ALWAYS transfered to both tires. You really do not want a spool on a daily driver.

Selectables are where you can either manually, electronically or via an air actuator, lock and unlock the differential on demand. You have the benefits of an open differential and a spool in one package.

 

Ok more questions bout everything. I wanna get basicly Stock of what the 6.7's have but am not sure of which way of doing it. I know of Fuel plate, injectors, exhaust, Banks power systems, turbos and what not. Right now its fully stock with 250k KM. I know this is gonna be costly but this is a over time thing but I like to get all the info before I get into stuff. I have asked many questions all the time of basicly the same topics as right now but never get it fully cleared out. I have been told not get injectors just move the fuel plate. How do I go about moving the fuel plate and if I move it how much more power do you think will be given? Also I am looking for a good tranny to handle all this power but cant find any, anyone know of a good one for my 94 12v? Thanks once again to all and any advice that may or may not get through my thick skull!

 

Just to add to my last question, I was on Dodgehouse site that you work for I think and was reading all the things to go for first for upgrades which cleared up a lot stuff but I still dont know which way to go bout it for my old 94 12v.

 

Heh, being up late brings too many questions to my head, I was told before I bought my truck that it had Load lifters in the front but I wanna put some in the rear cause last truck I hauled pulled my rear down a lot, are load lifters possible with lifts?

 

Matt,

The easy upgrade on a 12V is moving the fuel plate forward, but it's not going to net you a HUGE increase in power. You may see a 30 - 50 HP gain at the most by moving the stock plate.

The main limiting factor is the turbo. You're only pushing about 18 - 21 psi of boost through it at the most. With that, you're limited as the to how much fuel your can push.

Easiest way to squeeze power out of that 12V is with a bigger turbo, bigger sticks, new fuel plate, new delivery valves, a 4K governor spring kit and AT LEAST upgraded valve springs.

As far as transmission, you have plenty of choices there too. If staying under 450 HP, the tranny mods are relatively minor. Once you start going over that, you need to replace hard parts.

The choice of parts ultimately comes down to how much power you want to make and how much boost.