4 wheel drive

[Dlowe]

We got some snow so I decided to see how it performed in 4 wheel drive. On level ground, compact snow/ice all four seemed to bite. In 4L in granny on a steep hill only the right rear spun out? I really expected more drive from the other corners? What should I expect?

 

[SrBeaver]

Unless you have LSD or a Locker you will only have 1 wheel per axle that is the power tire, also the tire that loses traction will be the one that spins (path of least resistance). I would double check to make sure that it is fully engaged in 4L and try again. Is there a body lift in it? Dana 20 is it a twin stick?

 

[Old Dog]

Without lockers front and back you will only have one front tire and one rear tire pulling.
Did you have your front hubs engaged?

 

[BajaEdition]

truth of the matter is, with an open diff you are truly in 4x4.
even with one wheel spinning. the problem is that with a differential your axle is designed to let you go around corners without chirping a tire. In other words allow one wheel to spin faster, the problem is, when in a uneven shear surface (shear being the ability of the surface to break free) the diff feels like it is doing it's job.
let me explain a bit. in a perfect world a 2 wheel drive always has 2 wheels getting 50 % of the horse power, but we have torque. now what happens in a open diffed vehicle is on tire is on a rock and it takes 50 pounds of torque to turn that wheel, the other is on snow and can turn at 25, so the diff seeing that it develops 25 pounds of torque at the spinning wheel only gives 25 pounds to the other wheel and the spyder gears spin with the spinning wheels at 50 pounds of torque. 25 it takes to spin the one side and 25 to the spyder gears. Now let the torque build up under the spinning wheel and the snow disappear till it takes 50 pounds of torque for the spinning wheel to hook up and get traction and both wheels turn and you are free.
But that will not happen

SOOOOOOOOOOOOOOOOOOO

we buy a Limited slip or a locker,

A locker locks the diff and 50 to 50 split is all the time so if the stuck side gets 50 pounds and can turn, the other side gets that, how ever they are locked and need to spin at the same speed always (auto lockers not discussed here)
and a Limited slip through either clutches ( bad, wear out fast) or gears (very good) tighten up on the spinning side till it matches the torque needed from the other side to turn both at the same time.

you truly had 4x4, you just need a locker or a Limited slip to be able to use it when you want. One thing to consider if you are in snow a lot is a selectable locker as there is an effect called crowning that makes auto lockers or full time lockers scarey in the snow

 

[BusaDave9]

This thread sounds like the debate on myth #1.
http://www.jeep-cj.com/forums/f49/common-4x4-myths-11138/

 

[Dlowe]

Hubs were in, it doesn't have a lift. I will check to see, maybe it wasn't fully engaged. Would it drive the rear but not the front if it wasn't completely engaged? Twin stick? Do you mean the Transfer Case has two? It does not. One for the Transmission and one for the T case. I expected it to be like a goat in rough terrain. Lockers sound expensive.

 

[BusaDave9]

only the right rear spun out? I really expected more drive from the other corners? What should I expect?

With an open diff, once one tire slips the other tires won't be able to pull any harder unless you have lockers or at least Limited slip.

 

[hagar]

tap or jab the brake pedal to make the other wheels turn

 

[BusaDave9]

tap or jab the brake pedal to make the other wheels turn

That can help. especially if you have Limited slip.
With an open differential you can easily spin one tire on ice even if the others are on dry ground.

 

[BajaEdition]

Dlowe
put that puppy up on 4 jack stands and start it up in 2 wheel drive, both rear tires should spin, now put it in 4x4 and lock the front hubs in, all 4 tires should spin.
that s how you see if your 4x4 is working

now, another question comes up
what t case do you have?

remember that is a old jeep and there is no telling what mods have been done to it,it could have a t case with a differential in it making it an all wheel drive and not a 4 wheel drive.

but first do the 4x4 test. after that we can continue with the discussions on traction

 

[Dlowe]

Something made me think it was a Dana 20 , how does one confirm what it is? Shift pattern is.....all the way forward is 4H - 2H - N - 4L.

 

[BusaDave9]

Unless a PO has swapped out your TCase you should have a Dana 20 . They stopped making the Dana 18 in 1971.
The rear output of the Dana 20 is centered. The rear output of the Dana 18 is on the passenger side. Take a look at your rear axle. If the differential is centered you most likely have a Dana 20 . If it is on the passenger side then you have a Dana 18.

 

[BajaEdition]

Holy jeepers, I was thinking you said it had an offset rear axle, I must be getting threads confused.

 

[Dlowe]

So what I found today was that it wasn't fully engaged in low lock, Once it was all the way in I do have drive to at least one corner front and rear. Interesting to me that it would drive the rear (not engage the front) when partially in. Can someone explain that?

 

[BajaEdition]

the rear is default, the front is option, the case will always drive the rear