Any one tore into one or tore one down and put it back together? Would like the skinny of how it works and locks up.

 

The AAM 11.5 limited slip differential is very similar to the Quaife differential. Quaife has been making them for many years and it looks like the AAM is very close in the same/similar design. Basically it is a torque biasing differential - they have no clutches to wear out and should last as long as a standard open differential. They do not require the LSD additive, and suggest that you do not use any gear oil that contains the additive. If you want to get a better idea about them, check out http://www.quaifeamerica.com/ their info is as close as it gets to knowing more about the AAM units.

CD

 

Even the Quaife explanation of an open diff is inaccurate. They say that an open diff shifts power to the wheel with less grip. Not true. An open diff transmits even power at each wheel all the time. So if one wheel is on ice or off the ground the other wheel transmits the same power to the ground. Zero or almost zero, but both the same. The lock Rite can't do that as much because it must send power (to spin one wheel) through a gear set similar to a worm gear. In a worm gear the power can be set through the worm to the bull gear but not from the bull gear to the worm gear. This is the principal used in worm gear winches to hold the load. Our diffs are not very aggresive and can spin some but they work better in many situations than some designs that simply slam in when a certain speed difference is sensed or that just simply lock the two axles together.

I'm not very good at explaining these, but more info can be had by looking up the Torsen differential or going to the AAM site and finding the Lock Rite.

Wetspirit

 

????

An open diff DOES transfer power to the wheel with less grip. It doesn't actually transfer the power but that is just what happens. If a wheel is in the air, it will receive all the power. That is how the spider gears work. They allow one tire to spin at a different speed than the other. This is why people who rockcrawl or even do regular offroading prefer lockers. A locker will transfer even power to both tires all the time.

 

Yep! What he said. ^

 

Nope. Both wheels, with an open diff, put the same torque to the ground all the time.

That's why we get stuck with them. When one wheel looses traction and begins to slip the other wheel is putting the exact same torque to the ground. So we get stuck. No extra torque is being sent to the slipping wheel, only higher RPM. The same torque, and therefore the same forward force to the ground. So the wheel with the least traction determines how much forward force we can deliver. Ice under one wheel means it slips and spins, but the other wheel is putting the same force to the ground. One is spinning and one is not. Different speed, same torque.

That is why lockers work to get us unstuck. Both wheels turn the same speed, but one has more traction. So we can get some torque to the ground with that one wheel that has traction, and get out.

Open diff means always even torque at different wheel speeds. Locked diff means always even speed with different torque at each wheel.

Many dune buggies use individual rear brake controls to take advantage of this feature. When one wheel begins to spin the brake is applied to that wheel, and since both axle shafts see the same torque, the other wheel with the greater traction gets more torque (equal to the slipping one with brake on) and drives the buggy forward.

When you see a statement that says something like "all the power is being sent to one wheel" on our trucks or any vehicle with an open diff, it is incorrect. Just as the statement "our trucks only have three wheel drive" is incorrect.

In an open diff only the speed is different, not the torque. This isn't rocket science and it's very old technology.

Do some more research and you'll see what I mean.

Wetspirit

 

Exactly.

Wetspirit

 

rockcrawler304,

Imagine a rock crawler climbing. One wheel is off the ground but the crawler continues on up. Are you trying to say a wheel off the ground is propelling the vehicle as well as the wheel that is on the ground? Or delivering equal torque to the ground? How can equal torque be sent to the ground if one wheel is in the air?

A locker applies equal speed to both wheels but almost never equal torque.

The open diff applies even torque but almost never equal speed.

Wetspirit

 

Now you are trying to throw physics into it by saying your transfering torque "to the ground". It all depends on how technical you want to get. An open diff gets power transfered to the ring gear and then to the spider gears and through the axle shafts to the tires. If one tire is on ice and one on solid ground, the tire on ice spins just like you said. I have actually been involved in a "experiment" (alcohol was involved ) and took a truck with open diff and held one tire with a machine (both tires off the ground) and let the other tire spin. We were able to let the machine off the stopped tire and hold that tire by hand while the other tire was still spinning. There was very little torque being applied to the stopped tire. So I do not belive equal torque is applied to both tires ALL the time in an open diff.

A locker puts equal power to both tires all the time. Now if one is in the air you cannot say it puts power to the ground but, it still is putting power to the tire.

 

rock,

Next time you do that experiment simply slow the spinning tire with a 2X4 against the ground and note that the other wheel speeds up that same amount. Whichever one you stop the other one speeds up. And either one can be stopped because it's an open diff. While driving, if more torque is applied than the two tires can deliver, and one begins to spin, the speed goes to the one with the least resistance but the torque through the axles is the same. The max total torque sent to the ground is determined by the tire with the least traction in an open diff. And they are always the same. The tire on ice deliveres the same forward push as the tire on dry ground. It just looks exciting because it's spinning, but it's pushing the same as the one with traction. Now lock the two axles together and the torque becomes un-equal. The one with more traction is able to drive the truck forward. The axle shaft driving the tire with better traction gets more torque and it's tire applies more forward force, because it has more traction.

Wetspirit

 

Well it is obvious we both know how an open diff works and how a locker works. It's just a matter of how you/we explain the function.

Simply put....Open diff= NO good
Posi style diff= Better
Locker= Best for traction

Wether the torque is put to the ground or to the air, the locker is the way to go.