Limited slip vs full lock

[0ldman]

I've got a 98 Ranger, 3.0, 5 speed, 3.73, 4wd.

In 4H it is definitely limited slip, it will alternate which wheel pulls and tear my driveway up. I haven't had the chance to test this yet, but does it go full lock in 4L? I've pulled stuff with this truck in 4L in the past and it seems like all four wheels were locked in (had another car stuck down hill in the mud) but it's been years.

 

[Curious Hound]

It's most likely just limited slip unless someone messed with it. There should be a tag somewhere on the axle tube or differential that will tell you exactly how that axle was configured from the factory. The older axles had a metal tag attached to one of the diff cover bolts. There is some great reading in the "How To Tech" section of this website (click the tab at the top of the page) that explains axle tags, axle codes and a lot about open, limited slip and locking differentials. There are many different models using different technologies.

 

[0ldman]

I've got the door tags, everything is factory original aside from the tailgate and front bumper, four wheeler and deer incidents... it is a 7.5 3.73 limited slip.

So it is just limited slip full time then?

I was hoping I was wrong about that.

Thanks for the info.

I'm a big Ford nerd but have little experience with 4wd. I'm more in to the small block and older cars.

 

[mavereq]

The diff doesn’t know if you’re in high or low range. It just has more gear reduction so it’s less likely to slip.

 

[0ldman]

I was hoping for some kind of an electronic locking mechanism, but I wasn't too optimistic that they'd have one on a 98 model.

 

[RonD]

The biggest drive train problem to over come in a 4 wheeled vehicle is that wheels on one side of the vehicle need to turn faster than wheel on the other side EVERY TIME you go around a corner.
If you had a solid axle across then the outside wheel on the turn would be dragged because it would have to spin at same speed as inside wheel.
On hard dry pavement that means lots of broken axles, lol.

And that's called a Locking differential, no slip, so you MUST drive in a straight line no turning.
Now on slippery or soft dirt/gravel the outside wheel can be dragged with less chance of axle damage, so users gamble.

Limited slip
Ford's Trac-Lok uses clutch discs that will slip when you go around a corner, there is a additive use in differential oil called a friction modifier, that allows this slipping, but it only slips a bit, if difference in axle RPM is too high then clutches lock so no "spinning wheel" like you would get on OPEN differential.
I.E. both wheels would spin on ice with limited slip, not just the one.

If only one wheels spins on loose/slippery surfaces then you either do not have limited slip or the clutches need replacing

Posi-traction is Chevy's version of limited slip, similar to Ford setup

Torsen traction uses gears instead of clutches this is a better and, of course, more expensive limited slip.

A locking differential would have a outside activation mechanism, which would only be used when going straight or on loose surfaces, but they can be a bit squirrely when cornering since traction can shift from one wheel to the other without notice.

All Ranger 4x4s came with OPEN front differentials
So the easiest wheel to spin gets ALL the power of the front drive shaft

 

[mavereq]

Actually, that’s a spool. Lockers disengage on turns.

 

[Curious Hound]

Actually, that’s a spool. Lockers disengage on turns.

Doesn't that depend on the locker? An electric locker, ARB air locker or a locker engaged/disengaged manually with mechanical linkage would stay locked. A locker like the Aussie lockers I use has springs that allow it to disengage around corners UNLESS power is being applied via the pinion gear so that the cross pin forces the side gears to stay engaged. The heavier your throttle foot - the more force preventing the locker from disengaging.

Eric B

 

[0ldman]

I wonder if this one has some kind of limited slip on both axles. Under acceleration in mud all four wheels spin equally, but trying to carefully come up my iced over driveway had an alternating spin/grab/spin/grab/spin and you can follow the track up my driveway.

I was hoping for some kind of electronic lock, but like I said above, wasn't that optimistic for a 98 model. Sounds like the method used on modern stuff is using traction control and the brakes to keep the wheel spin to a minimum.

My father in law's 88 had a solid front axle and a locked rear. Not sure if the front wheels were locked when engaged but the rear was. It chirped every time you turned, wore the tires, etc...

 

[mavereq]

Doesn't that depend on the locker? An electric locker, ARB air locker or a locker engaged/disengaged manually with mechanical linkage would stay locked. A locker like the Aussie lockers I use has springs that allow it to disengage around corners UNLESS power is being applied via the pinion gear so that the cross pin forces the side gears to stay engaged. The heavier your throttle foot - the more force preventing the locker from disengaging.

Eric B

That’s a selectable locker. You’d need to specify if that’s what you mean. A Detroit or grizzly locker disengages on turns. The new ones actually do a great job. Selectable lockers do fully lock, but you run them open 90% of the time.

 

[bobbywalter]

I have to come back to this one....

 

[Curious Hound]

That’s a selectable locker. You’d need to specify if that’s what you mean.

Selectable lockers are still called lockers. That's exactly why I said it depends on what kind of locker. Yes, the Detroit and Grizzly operate like the Aussie I mentioned.

 

[mavereq]

Selectable lockers are lockers, but to say lockers work like spools and then to later bring selectable lockers into the debate is really just confusing for the OP.

 

[RonD]

If axles are not LOCKED together then it is Limited-Slip

It can be a better Limited-slip than Fords Trac-lok or Chevy's Posi-traction but it is still Limited Slip, if axles are not LOCKED together

It is black and white, there is no grey area here, lol,

 

[bobbywalter]

If axles are not LOCKED together then it is Limited-Slip

It can be a better Limited-slip than Fords Trac-lok or Chevy's Posi-traction but it is still Limited Slip, if axles are not LOCKED together

It is black and white, there is no grey area here, lol,

not a auto locker like a Detroit.