>> Problem: My wife was told by someone she knows that she'll be more prone
to
> breaking limited slip diffs because she has 4wd (and the big engine) and
> she'd be better off just with a regular rear diff. I think she'll end up
> stuck in more fields.
I'm no expert, far from it...
GM has used a rear "locking" differential called the Gov Lock which is I
believe manufactured by Eaton. It was in use as far back as the mid
eighties, and I know for a fact it was in use on the later model (torsion
bar) Z71 "off-road" chevrolet package. It may or may not still be in use
today.
Since unfortunately "locking" and "limited slip" are often tossed around and
mixed up by sales staff who do not understand the difference, it would be
possible that this diff is the one that was being referred to.
I've had the chance to witness one of these differentials in operation, and
from what I can see and understand, it works on the principle of centrifugal
force. Something in there causes the differential to lock up (not a positive
engagement, I believe, still based on the clutch pack method that is common
in GM posi and Auburn gear LSDs). The point here is that the diff has to
spin up before it actually "locks" in. It is not positive engagement from a
standing stop, but there must be a significant amount of wheelspin to get
the axles coupled together via clutch packs.
This is acceptable for a single wheel pickup with a moderate load, but
thinking of your application, gooseneck horse trailer, heavy dually truck,
and muddy and slippery conditions, I have some serious concerns over the
viability of using this differential. It seems that the added traction and
rotational mass of a duallie would put an extreme stress when the
differential starts biasing load when already having attained some wheel
speed. Of course, since there are clutch parks it is not a shock load, but
still a significant load.
I would ask your salesdude for a description of the inner workings of the
differential, and ask about exactly how the differential engages. For your
application a clutch type LSD which is always engaged and is always biasing
would be best, however, if the truck has a governor type rear differential,
you might be best to try and get something always biasing or simply open.
As far as having the added traction of a limited slip rear end on the
vehicle, it will probably be one of those things that is needed only once or
twice a year, but will make the difference between having to start yanking
and driving out. However, having to pull out a brand new truck that weighs
25000 lbs with a trailer in tow must be a fun job :-(
J-L
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