RE: Is my LSD broke?

From: Bernd D. Ratsch (bernd@dodgetrucks.org)
Date: Mon Mar 30 2009 - 15:55:59 EDT


The LSD (Trac-Lok) diffs are designed to give power to the wheel with the
most traction. The slipping wheel won't get much power to prevent slipping
(hence: Anti-Spin).

You can, however, get the diff to lock by lightly applying the brakes while
moving.

One thing though...if the clips in the clutch pack break (which happens
quite often on the 9.25" diffs), you'll also get the same symptoms like you
are describing.

- Bernd

-----Original Message-----
From: David Gersic [mailto:info@zaccaria-pinball.com]
Sent: Monday, March 30, 2009 2:30 PM
To: dakota-truck@dakota-truck.net
Subject: DML: Is my LSD broke?

I got stuck in the snow yesterday. One problem was that the 4WD is dead, but
I'm pretty sure that that's an electrical issue. But the LSD isn't
electrical.

What we got, starting Saturday afternoon was rain, changing over to sleet
and freezing rain, changing over to snow overnight. By Sunday morning, what
was on the ground was about 1" of watery slush topped with 6-7" of snow. The
air temp was just below freezing, so the snow was the heavy wet stuff.

I backed out of the driveway ok and swung around to about a 45 degree angle.

Put the truck in 1st, and stuck there. If I gave it any gas, one wheel or
the other would spin, and the whole truck would slide sideways down the road
crown toward the curb, but no forward motion at all. I could even spin one
wheel by just putting it in 1st gear (manual trans) and letting in the
clutch.

With an LSD (confirmed both by the "Trac Loc" sticker on the rear axel, and
the "spin the wheels by hand" test, shouldn't I have been getting power to
the non-turning wheel, rather than just spinning the one that's slipping?

Is there a minimum torque that the spinning wheel has to have applied to get
the clutches to engage on the other (non-spinning) wheel?

This stuff was slippery enough that I could push the rear end of the truck
sideways by myself. I did this to get it closer to straight, shoveled out
the rear wheels, and got about 5' further down the street before sliding
sideways to the curb again. It took four attempts like this just to get
moving forward with any momentum.



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