some questions about LSD operation

[Bunn]

Ok, here is the problem. My truck is equipped with a LSD or so the window sticker on my truck says so. However I don't think I have it. I've noticed that on ice or hardpacked snow, only the passanger tire will turn. I jacked up the rear end and spun the tires by hand and only one will spin at a time.



So, is this normal? Is this a differnet type of LSD? what gives. I'm new to the diesel and heavy duty world but I know that my 94 Dakota had a LSD and both tires turned all the time on ice or snow.

 

[rbattelle]

I was just today thinking about the "jack it up and spin one wheel test" as it relates to the Trac-Loc limited slip system we have. Here's how the system works, straight from the service manual:



"When one wheel begins to spin the pinion gears on that side are forced toward the pinion brake shoes. The pinion brake shoes cause frictional drag on the opposite pinion gears and the side gear. These friction forces transfer the power to the opposite wheel. Once the friction forces are overcome, differentiation will occur. The torque will be continually biased by the frictional forces to the high-traction wheel"



That seems to imply (to me, anyway), that some speed is required to get the limited slip system to work. If that's true, then spinning 1 wheel by hand may well result in the other wheel spinning the opposite direction. I know I have the limited slip, since I've had the rear diff cover off. I will try the "spin wheel by hand" method next time I rotate the tires.

 

[RobbieH]

Since it works the same as the Torsen, read this, it should help.



http://www.torsen.com/general/general_faq.htm



This is not at all the same as the clutch type LSD you had in your Dakota.

 

[Elite1]

That is a good question, some posi's I have driven in the past, require you to slightly apply the brakes in order for the other wheel to grab.

 

[RobbieH]

With all limited slips, if you have one tire with zero traction, applying the brake will help.



If you read the above article, you will see the gear driven unit in the new Dodge works by multiplying torque. Multiply anything by zero...

 

[radar doctor]

Good Article

Thanks Guy's. . I'll look at Mine...