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Someone was saying that limited slip is a regular diff rear, one wheel spinning.
I thought that you had 3 types.

1. Open = one wheel spins
2. Limited Slip = switches between wheels, rarly both spins
3. Locker = both wheels spin most the time, unless turning

So whats the deal? Need 'Rearend 101' class here. hehe
 

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Limited slip lets one wheel slip when threshold torque limit is exceeded. Limited slip can be achieved with friction plates like in Trak-Lok or machined cones as in Auburn.
 

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Not an "expert", but here's my take...

First off - limited slip (Ford Trac-lok / Chevy "posi-traction") is not the same as a "open differential". In a open diff, for all intents and purposes, you're really only putting power to the right rear wheel/axle. You can prove this point by getting in a car with an open-diff (and enough power to light-up the tire) and mashing the gas from a stop and turn either left or right. If you turn to the right - the right tire will spin hard as you go around the corner with the weight shifted to the left side of the vehicle. It's a different story with a left turn. Once the (right) tire spins, and you turn left - the car will fish-tail because you've lost traction due to the spinning right tire - which is carrying most of the (shifted) weight on the right. (It's a lot easier to "test" this when it's wet. Just be careful! :)

The "limited-slip" differential has the addition of clutch packs that tie the left axle to the right. As pointed out - there is a certain torque that will "break" the connection - allowing the clutches to "slip" for smooth turns as the outside wheel turns faster than the inside one. A properly working limited slip diff should smoke both tires all the time - not just some of the time. Even in a hard turn if you start spinning the tires, both will continue to spin and you'll "fish-tail" in either direction. (That's what my '86 does.) A fact about the Ford trac-lok is that in time, as the clutches wear, your limited slip will slowly turn into almost an open-diff. On the 5.0 board, everyone calls it the 1-wheel-peel, and that's when you know it's time to install a new clutch pack in the rear. (I don't know if Chevy / Mopar use the same clutch-pack setup??)

I don't know too much about lockers - but there are several types. I *think* a "Detroit Locker" uses a ratchet type setup, where the ratchets are allowed to "unlock" when taking a corner. (I've heard these can be real noisy and annoying on the street.) But unlike a worn-out "limited-slip", the "locker" will absolutely NEVER give you a 1-wheel-peel due to the mechanical connection between the axles. (Unless it's broken of course.)

Wow... I wrote a lot...
 

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You may as well add the fourth type:

spool = Solid connection between axle gives full time traction to both wheels. Just don't plan on turning. This setup is used on drag cars.
 

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An open rear puts the same power to both tires during normal accelleration. The reason you get the signature "one wheel burnout" is this: Think about the direction the driveshaft is turning. The twisting force of the driveshaft going lengthwise with the car is transformed at the rear end to the opposite direction- sideways. The driveshaft is trying to turn the entire rear assembly like it was a propeller. This force plants the left side tire firmly on the ground and lifts the right side tire off the ground. Ok, not off the ground, but it makes it lighter. To prove this fact go out amd mash the gas in drive and leave a right side smoker. Then put it in reverse and do the same thing. Guess what- the left side will do the smokin!!

Anthony
 
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