Re: Limited Slip Conversion

From: Kevin Sellstrom (ksellstr@softcom.net)
Date: Sat Nov 09 2002 - 11:52:54 EST


>I drove it in the rain for the first time the other day, and that brings
>up my question. It is all too willing to spin one tire leaving every stop
>light.

This is my first winter with our Dak and I noticed the same thing,
especially with the LSD that currently acts like a locker/spool. The truck
is light, the throttle response is immediate and powerful, the transmission
is firm...slips all-over in the rain. My first investment will be a
handful of sandbags this weekend.

> I am considering adding some sort of limited slip to the currently open
> rear differential. I see units are available from many suppliers
> including Auburn Gear's Supergrip, Dana Spicer's Track-Lock, Mopar's own
> Sure-Grip, and the Detroit Locker.

Availability may be a little different depending on your axle model (Mopar
8 1/4 vs. 9 1/4)...then again maybe not.

I've got the 8 1/4 with the factory "Trak-Lok" in our Dak. Granted, it
needs the fluid changed due to no friction modifier added at the factory
(PO drove it 30k miles this way!), but it does not lock very positively for
four-wheelin'. For average street use however, it should be fine. We had
an Auburn in a Ramcharger w/9 1/4 diff. and found it to be excellent. It
locked very positively when needed, and was smooth and quiet on the road.

I'm not sure if this is still the case, but Mopar used to use their own
Sure-Grip in the "light-duty" axles such as the semi-floating units found
in the Ramchargers, 1/2 ton trucks, and most vans and cars. In the heavier
axles found in 3/4 ton and larger trucks however, they spec'd the Dana
Trak-Lok which is much sturdier but does not lock quite as solidly. The
Sure-Grip is a cone-clutch type while the Trak-Lock is a clutch-pack type.

I've found that the cone-clutch models do their best to lock solidly if one
wheel spins free, such as on ice or in the air. The Trak-Lok however
requires a little bit of pressure on the loose side in order to lock up,
and generally does not seem to lock solidly - as is the case with the
Trak-Lok in our Dak. I've used a little bit of e-brake if one tire is
spinning to give pressure to that tire and force the other to pull. The
Trak-Lok can take a lot of abuse and/or power, hence Dodge placed it in the
HD trucks.

I've heard personally that the lockers are generally the strongest, they DO
lock positively as they employ a ratcheting mechanisn instead of clutches,
and they are noisy and rough on the road. A friend HAD one (Detroit I
think) that he replaced with an air locker. The Detroit locker was
dangerous in the snow because it didn't allow the tires to slip a little,
it wanted to lock-up in every turn and made the truck want to spin out any
time he turned a corner while applying even light throttle. It was great
in the dirt however! ;)

We also run RedLine synthetic fluid in our diffs which definitely helps
them run cooler. The RedLine 75W90 gear lube advertises that it has some
friction modifier in it, that you should try using it without before adding
any. The Dana trak-lok's and the old Sure-Grip do not seem to require the
additive but the Auburn DID require about an ounce of the RedLine
additive. Found out the hard way...

"I don't do a lot of off roading, but snow is on the way.
In particular the Dana Track-Lock seems really reasonably priced."

I'd suspect this would be fine, my old Trak-Lok has not been a problem in
the snow, and is a HUGE improvement over the open diff. All of these are
high quality and should be fine, but I might think twice about any locker
for snow use.

Good luck, and let us know what you choose and how it works!

Kevin Sellstrom, W6KTB E-Mail:ksellstr@softcom.net
             ***Wilton, California***

'99 Dodge Dakota 4x4, 5.2,
'69 Dodge D200, 4x2, 318, NP435,

Also: '83 Volvo 244Ti, '85 Volvo 244, '68 Volvo 122S, '98 Specialized
Rockhopper A1FS



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