one_speed_heuer

I have a 99 Cherokee, 4.0 Auto with the NP231, I was looking up stuff on Differential Lockers and how they help with offroading a great deal. But with the 231 I know you cant drive on dry pavement because the differential isnt open(at least thats what I was told, it also starts to hop a bit when I turn tightly). I was confused about this locker idea. And was wondering if I might have a Limited Slip Differential or whats going on. I still have yet to get stuck in 4wd, The other day I got stuck in someones driveway in 2wd because the right side was in mud but the left side was on concrete, when I put it in 4wd it hopped right out. And I thought without lockers the tires with the least amount of traction would get the power. So this is confusing me a lot.

Heres part of the factory spec sheet, from Chrysler.
DGB All 4-Speed Automatic Transmissions
DGSS 4-Speed Automatic AW4 Transmission
DHAP Lock-Up Torque Converter
DHNS Command-Trac Part Time 4WD System
DHSP Floor Mount Automatic Shift Lever
DJHS Dana M30/181MM Front Axle
DMDP 3.55 Rear Axle Ratio
DRAS Corporate 8.25 Rear Axle

Right now I have a 3 inch lift, in December when I get back from Basic I plan on getting a 4.5 inch long arm lift, maybe a 6 inch depending on how I feel, and I know ill need a SYE. But I was debating on Lockers, as of now I dont do any super hard offroading since there isnt much in WI but would love to do more stuff. Its mostly mud and trails.

Thanks for any help

schirm

The short answer to your question is yes you can put lockers in your diffs with the NP231. Just don't put it in 4wd on dry pavement. Which you arnt supposed to do even with open diffs. But I would suggest making sure you have front and rear recovery points and all recovery equipment needed before buying lockers and a bigger lift. I would also make sure you have an auxiliary transmission cooler as well. You probably do but some jeeps didn't come with them in stock form. Basically, lockers, as great as they are, should be among your last modifications in your build. For example, you want to have the gears, tires and lift in hand before installing lockers.

one_speed_heuer

I know I'm not supposed to put it in 4wd when I'm on dry pavement but I figured it out on the test drive by accident (the owner hadn't driven it in a few months and the snow melted on the roads). And I was always taught that a hitch on the back works. Or use the axles for recovery, from ditches in winter. I'm sure most people would disagree. And I do plan on eventually getting some tow hooks/rings. The lift was a long arm because I heard it's a better ride and it should make the axle geometry have better angles.

I was mainly confused by the fact that I know I don't have lockers. But in 4wd I thought that only 2 tires would get the power and they should be the ones with the least traction. I guess my question may be: does the np231 send power to all 4 tires when it's in 4wd?

schirm

No, it does not.

schirm

The NP231 sends equal torque to both differentials when in 4wd. The differentials then "differentiate" torque to either tire to allow the 2 tires on each axle to spin at different rates. This is what allows a vehicle to turn without chirping tires. The outside of turn a radius is larger then the inside. So for example, if you are turning left then your right tires will spin faster then your left tires because the differentials allow the tires to differentiate spin rates. This is great for street driving, bad for off road. Because the natural consequence of differentiation is, as soon as one tire per axle loses traction then all the torque will be applied to that tire. Differential lockers stop or alter differentiation so that one tire on an axle doesn't receive more torque then the other, thus, all you need is one tire on that axle to have traction in order to move. As far a transfer cases go, some are designed more similar to an open differential and do allow different amounts of torque to be applied to each differential. But the NP231 is not one of them. It is chain driven, which implies that once you engage 4wd then a chain is wrapped around the front driveshaft output yoke and can't turn at any other rate then what the trani is telling it to without breaking. That's what you want in a 4wd rig.

SteveMongr

It's the 242 case that you do not want to use a front auto-locker. It would make Full-Time 4x4 on pavement,snow and ice obsolete.

Fred/N0AZZ

I recently added 4.56 gears and Detroit Lockers to my "99" same setup as yours. It should have been my very first upgrade I did to my XJ as it gave me more bang for the buck than any single thing I have done.

To tell the truth I really don't notice the rear locker on the turns that much at all. The only thing you will notice a little is when let and on the gas is a mild clunk from it, same when you place it in gear. No its not my drive shaft it is a new custom made and being I increase3d the lift from 3 to 4 1/2" I did install a SYE plus shimmed the differential.

I now can go on trails in 2 wheel drive where before I had to use 4wd to get through. The locked rear makes quite a difference for sure and now when in 4wd I go places I never could before. IMHO they are a win, win decision all the way.

cleenrob

i get the same with my rear detroit, i dont hate it but id rather auto-lock the front. that way it would only be active in 4x4, not all the time like the rear

Fred/N0AZZ

Its only active when you have it in 4wd anyway, when not in 4wd you never know its there . Exactly the way it was stock you never have the front wheels engaged or locker engaged till you select 4 HI or 4 LO. I have a 99 with a NP231 D30/C 8.25.

One of us are confused could it be me???

Jordansjeep

Jordansjeep

aka"dude"

Buy a winch. If you use the winch allot, then get some lockers. I got my lockers first and the traction is intoxicating but now wish I had the winch first because of the security.

TRCM

Technically, yes, it does......as long as traction at all 4 tires is perfectly equal. The reality is, traction is never equal enough for all 4 tires to pull...period.

Once that traction is no longer equal, the differentials will differentiate that power side to side to each tire, and I still think the np231 also differentiates power front to rear as well.

00t444e

The np231 has no differential in it, the front and rear driveshafts are locked together in 4x4.

TRCM

Gotcha...looked it up.........didn't remember for sure if it did, but the way one of mine acted int he past, I'd swear it did (must be broke).

I KNOW the 203 in my old truck did...till I changed it.