Re: Determining Traction Aiding Devices in Diffs

[tsm1@domain.elided (Tom Mandera)]

>Again... as *I* understand things...
>
>The easiest test that will tell you if you have a locker or limited-slip
>that is *working* (not worn out or broken) is to raise one tire of the axle
>being tested.  With the driveshaft free to turn (as in the transmission and

Wow, John.  Nearly everything you posted seems counter to my train of thought..

:raise one tire, if it turns, no locker, no turn = locker

As I recall, most "permanent" (not ARB / Command Locker / whatever) lockers
allow one wheel to OVERRUN the driveshaft, but never turn SLOWER than the
'shaft.  Thus, you *should* be able to turn one wheel while the other is on
the ground, since the driveshaft won't turn, and thus the tire on the ground
doesn't have to turn, and the tire in the air can turn (though you may hear
the locker unlocking (think a typical ratchet mechanism, sliding "backwards"
on the ratchet results in clicks)

I would turn this around, and try turning the DRIVESHAFT with one wheel on
the ground.. if the 'shaft won't turn, good shot you have a locker (BUT,
could an Open diff be "stuck" or have "picked" the axle shaft on the ground
at this particular point in time?  making the same result?).

My undertanding on the limited slip units:

The Track-lok allows slipping all the time, but *limits* the slip.  Thus, it
acts exactly like an open differential, until the "difference" between one
wheel and the other becomes too great, thus the term "ramping up" the LS.
As the rotational difference increases, the clutch packs "ramp up' and bind
together, causing the fast wheel to slow, or the slow wheel to speed up,
resulting in the two axle shafts being fully locked together.  I believe
this situation persists until you get off the throttle and allow the
clutches to "unbind" themselves.

I've heard the older PowerLock works differently, in that it's locked ALL
the time, UNLESS it's forced to unlock.. this is much more like a
"traditional" locker

Again, Detroit/Lockrite's drive the slower of your two wheels, thus the
oversteer in corners (inside wheel tries to PUSH the truck wide in the turn)

So, how would I check for a LS or Locker?

Jack the axle up.. BOTH sides.  Turn the driveshaft.  If one wheel turns,
you don't have a locker (both wheels will turn the same speed with a
locker.. the same speed (x gear ratio) as the driveshaft, if one is
stationary, no locker)

If one wheel turns and the other doesn't, probably OPEN.

To test for LS... I can only think to turn the 'shaft fast enough that you
generate a good sized difference, and see if the other wheel picks up
speed.. OR, try holding the other wheel stationary and see if it gets any
more difficult to turn the dirveshaft.

Me?  Well, I knew I had a new Track-lok in the back of my '77 when I bought
it.. to test, I took my Scout to a local mud hole (it was quite shallow at
the time).. we have a lot of greasy clay around here.  Anyhow, I drove into
the mud hole, turn the wheel hard left, and floored it (okay, it's only a
4cyl y'know.. it wasn't all *that* impressive) in 2wd, and then felt the
rear end "walk" sideways as the two rear wheels locked together.

On other occasions, I've been known to punch it in reverse (slip the clutch
just right) on some smooth asphalt, and my little 4cyl will leave two black
streaks.. "Yup, track-lok works"

OTOH, my '72 with 304v8 and an open rear end only leaves ONE (very) black
streak, and it doesn't walk sideways in the mud when I hit the throttle.

YMMV, I may be wrong and John right.. the FAQ has some info (I think) on
figuring out if you have an Open, LS, or Locked diff.

-Tom Mandera, Helena MT
http://www.tmcom.com/~tsm1/scout
'72 Scout II (to get Lockrites when I finish this legal battle...)
'77 Scout II (with a new Track-lok in back)