You are both right (and wrong):

Most LS's can only transfer 1.5-2.5x as much torque to the wheel with traction as to the wheel with no traction. The Ford LS is on the weaker end of the range.

So, if you have one wheel on wet ice and it only takes, say 5 ft*lbs to break it loose, then only about 10 ft*lbs will go to the wheel on pavement. This may not be enough to get you moving.

If one tire is in the air, nothing happens at the other tire because 0 ft*lbs x 2 is still 0. Putting the parking brake on sometimes helps because then some torque will go to the tire in the air, so the other tire gets 2x that amount.

A locker works the opposite way in that it takes torque to break the mechanism loose. This makes them a handful in ice, because the rear of the truck oversteers under power and understeers off power.

Axle - nice Politically Incorrect poster.

Ian

 

I agree with Ian on this one,

When offroading with my friend when we get one wheel off the ground, it just spins even with the LS, instead of the ebrake he usually just applys the brakes slightly, then the gas and the truck will go forward no problem. I don't do this in my truck, as it's open front and back :-\ but I still go and try my best :-)

as to the fact that you are still moving forward slowly, with one tire spinning, could be because yes, that tire that is spinning will eventually get the car moving, though that seems like it would take a LONG time, or if your LS is in fact wearing, it could be working only a fraction of what it should, transfering a very few percent of the power to the wheel with traction. Again my friends truck, for a while before we replaced his LS, if he mashed the gas from a stop, both would spin, but one significantly faster than the other, evident by the dark tire mark on one side, and a light one on the other.

Next time you try this, hit the brakes a little, and see how much it takes to get you moving, it should take much. It should be about the same amount it takes to slow down a few MPH at 45 when the person in front of you lets of the gas, but not as much as it does to stop from 45.

This is just what I know from my experience,
Correct me if I'm wrong.
Kris

 

One diff. that was not mentioned was the Dyneer Tru-trac. Tru-trac is like having two differentials in one. Right & left will pull seperately & independantly when turning. Like other open and lockers: true trac will pull together when vehicle is driven in a straight line.

I have built several diff's with true-trac for circle track racing on dirt. Result: better handling & vastly improved lap times.

Likewise, I also agree that OEM Ford trac-loc is wimpy when compared to Eaton-Posi or Auburn L/S. I have three Ford P/U trucks. One has Trac-loc, one has Auburn Pro and other has Eaton-Posi. I prefer the Eaton-Posi.

I would think that Ford would offer some other option for a L/S in their 11,000# & below GVW class vehicles.

 

Hi,
Could some one answer this because it's been bugging me for a while...
I do have LS so:
1. How would I test that it works OK? For instance, on a snow if I push gas, not hard but *enough*, the back of the truck immediately goes to the right side. Is it an expected behavior or I have to fix the LS?
2. I presume when the LS is broken I have an *open rear*, right?
Thanks in advance,
Alex

 

That is what happens when you have a LS that it working properly. If it was open, you would just spin. The movement to the side is because only one tire is moving the vehicle.

Ian

 

Yes.

I have the same condition as Dave [Bervinator?] the original poster. S'crew 3.55LS, 24K miles. With one tire on ice, it moves ahead slowly. I don't think it was the iced tire propelling me, I think it was the dry tire. From the info in this thread, now I think it might still be working as designed.

Anyway, I have an acquaintance who is an engineer for an automotive gear company. I asked him about it. Here is what he said:

If your limited-slip seems more like an unlimited-slip, welcome to the wonderful world of OEM limited slip diffs. All of the domestic 1/2 ton LSD's suck. None of them have enough bias ratio to be effective. The OEM's play a game of balancing the torque bias and chatter. Too low of torque bias and the diff acts like an open diff. Too high of bias and you get chatter (stick-slip noise) while turning. And remember, the OEM's are using the cheapest design from the lowest cost supplier who is building it with the cheapest materials.

Your best bet is to start with a decent grade of gear lube without any friction modifier. If you do not tow under abuse conditions, I would recomend a mineral based 90W gear lube that meets M2C105A specifications. [Note: that is a military spec.] If you develop a chatter condition, add 4 oz of friction modifier from the
Dodge dealer. If you continue to have chatter after this, add 4 more oz.
Be sure to drive for day or so after adding the modifier. It needs to impregnate the plates and that only occurs while turning.

END forwarded comments from engineer dude.

I asked him what he meant by towing under abuse conditions. He said "real abuse" like towing a full load uphill at high temps, not ordinary recreational towing.

He also said mineral oil is actually better than synthetic as long as we are not talking about abuse conditions.

He absolutely HATES 80W-90 gear oil. Says it is total junk, regardless of brand, and to run straight 90 instead.

I had intended to drain and refill per his recommendations but it's too damn cold to mess with now. I guess I will keep slipping on the ice.