Re: Lockers used with a manual trans

From: SandMan (sandman@linkup.net)
Date: Wed May 12 1999 - 07:25:08 EDT


Hey JY,
I'll try to answer some of you questions for you.

Sorry all, its kinda long!

> >> > -----Original Message-----
> >> > From: owner-dakota-truck@buffnet4.buffnet.net
> >> > [mailto:owner-dakota-truck@buffnet4.buffnet.net]On
> >> Behalf Of Jason Yates
> >> > Sent: Tuesday, May 11, 1999 2:32 PM
> >> > To: dakota-truck@buffnet.net
> >> > Subject: Re: DML: Lockers used with a manual trans
> >>
> ><snip>
> >
> >> > so I was wondering if anyone could explain the concept of a
> >> > locker to me. Also, I have the LSD and how does that work
> >> > with a locker?
> >>
A locker would replace a Limited Slip Differential.

A locker is a mechanical device that physically LOCKS the 2 axles in a
differential by splineing them together, but does allow separation of the 2
for cornering.

The standard "open" differential corners by allowing the inside wheel to
underrun (turn slower) than the outside wheel in the corner, in this
situation the outside wheel is the wheel with the most power. This is
accomplished through the "spider gears" which consists of a side gear
splined to each axle shafts & 2 pinion gears that are attached to the "cross
pin" in the differential case. while cornering they work as idler gears
allowing the 2 axles to turn a different speeds.

A locker replaces the 4 spider gears with a pair of spring loaded side gears
which are splined to the axle shafts. In straight line driving conditions
(or low traction conditions) the spring pressure against the side gears
keeps the axle "locked" together (50/50% torque split). However in cornering
the locker disconnects enough to allow an overrun (turn faster) than the
inside wheel which is getting most of the power. This is a touchy condition
since a loss of control can easily occur if traction is lost & the locker
re-engages in a corner it would cause the rear of the vehicle to whip out
violently.

Meanwhile the Sure Grip differential or Posi (Limit Slip Differential), is a
compromise between the 2, it uses friction discs (clutches) to hold the
axles together, there is no harsh locking & unlocking & has far better road
manners.

> >> I don't claim to be an expert, but from what I've been
> >> able to pick up, a
> >> locker is more aggressive than an LSD. Where the limited
> >> slip uses clutches
> >> to try to send some power to the stuck tire rather than
> >> the spinning one, a
> >> locker will actually lock the axle solid so you get a
> >> 50-50 torque split.
> >> An LSD will still let one tire spin if it's up in the air
> >> and the other one
> >> is completely stuck (although in practice you don't get
> >> anything this
> >> extreme).

except rock crawling in Moab

> >>
> >> The LSD is smoother on pavement. I believe a locker
> >> actually leaves the
> >> axle locked a lot of the time, then unlocks when it
> >> somehow figures out
> >> you're turning.
> >>
You were basically correct with your assessment of lockers Vs limited slip
differentials. In my opinion though, stick with the limited slip diff, it
works quite well & is MUCH easier on parts than a locker. You get almost as
good of traction performance with out the broken axles & worn out tires,
plus when you do a burnout, you still light up both tires!!! ;-)

Obviously the decision is going to be based on what you need your truck to
do, if you're rock crawling in Moab or serious mud drags in Mississippi
gumbo mud, then a locker is probably in your furture. BUT, if you intend
your truck to be a daily driver with good off-road capability, then a lift
kit, taller tires & shorter gears are a better choice.

> >> > What about the front drivetrain--any way to
> >> > improve this? Oh, and what is the front drivetrain? Is it
> >> > like a Dana something or other? Just need someone to sit
> >> > down and explain this stuff to me.
> >> >
> >> > A curious wheeler,
> >> > JY
> >> > Vegas '98 5.2L 4x4 CC
> >>
> >> The front axle is a Chrysler 7.25" (at least that's what it is in the
'95).
> >> No Danas on this truck. Since you can't unlock the hubs, it's not a
good
> >> idea to try to put a locker or LSD in the front axle. An
> >> ARAB or something else you could completely disable at will would work
> >> okay, but I don't know of anything available for this axle.
> >> ---------------------------------------------------------
> >> Jason Bleazard jbleazard@home.com Toronto, Ontario
> >> current: '95 Dakota Sport white 4x4 Reg. Cab V6/3.9L/5spd
> >> current: '98 Dakota Sport black 4x4 Club Cab V8/5.2L/Auto
> >> RIP: '95 Dakota Sport black 4x2 Club Cab V6/3.9L/Auto

Listen to Jason here, DO NOT PUT A LOCKER IN THE FRONT!!! Especially since
the front end does not have locking hubs. Due to how a locker operates by
overrunning the outside wheel in a corner, that wheel must have enough
traction in the first place to force the wheel to overrun. If you try to
corner on snow, ice, soft dirt, sand, even wet roads, the axle won't
disengage & your truck would push like plow!!! In a turn the 2 tires have to
travel 2 different distances in the arc of the turn, a locker wouldn't let
this happen unless you had good traction. If you were to break traction at
this point the front end will whip to the side, probably into
whatever/whoever is next to you, not good. If ARB ever makes an air locker
though now that would kick butt since you differential acts as a normal open
differential until you need the traction. If they do, I'll be saving my
pennies for that.

I have found that the limited slip diff is more than capable of getting you
out of all but the worst conditions. I have the limited slip in my 99' Dak
& had one in my old 79' Ford 4x4. I once cut a front tire on my old Ford in
a frame deep mud hole, but due the limited slip I was still able to get out.
I made through about 50 yards of soup, dragging that flat like a ladle, buy
the time I got to dry ground to change the tire, that 32" BFG AT tire was
off the rim and packed full of mud. So what that means is all the power
going to the front end was being lost as it was only spinning the rim inside
the tire, so my big 4x4 was only a 2wd truck at this point.

On my old car (76' Ford) I once had a poor mans locker (welded together
spider gears), was lock together ALL the time, NO SLIP!!! It was fun to
show off with, but I broke 2 axle shafts & ruined a set of tires with them,
all in less than 2 months time until I took it back out, wasn't worth the
headaches.

I hope this helps, & once again, sorry all for the lengthy post.

_________________________________

SandMan

proud owner of:

Flame Red 99' Sport CC, 318, FT-4x4, posi, trailer tow, Tire & Handling
package.
This truck ROCKS!!!



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