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The Anti Yam!
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I understand exactly how a Trac-Lok works, I have rebuilt, re-stacked plates, and swapped Z-springs in several of them.

I understand that the Power-Lok is a clutch plate style limited slip, like the Trac-Lok, and I know it has 4 pinion/spider gear setup, but that's where my knowledge ends.

What else is different about a Power-Lok that makes it so much better than a Trac-Lok. I have read that it is the most capable of all LSD's, even more so than a True-Track!

There does not seem to be a lot of info about it on the web, just mentions of a "Ramping clutch" device, and dished clutch disks.

So someone school me on it's inner workings.

Spank Ya :beer
 

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Due to the simple design each of the LS units function in a similar fashion, but you already know this. You have really hit the nail on the head in your original post when you mentioned the 2 pinion design and 4 pinion design.
The 4 pinion design is much stronger than the 2 pinion type, and the reason is because when the side gears are turning 1:1 or applying torque to both axles the pinion shaft(s) are taking the entire load of the axles.
If the center pin only touches two ponts, the entire load is spread through only two points. That can wear the carrier and puts a huge load on the pin itself.
This usually happens:



The pin sheers off and then the spider gears fall out, and the remaining section of pin can hit the pinion gear, and well,,,,,,,,it makes a huge mess.

With the 4 pinion design this load is spread across 4 points, and can be distributed evenly across the carrier. Also consider that the cross pins on the power lok is far larger than the smaller one of the trac lok, so strength is superior.
Just look at the size of this:



Ok, so we can agree that this is stronger, but the design of the carrier is also superior, the huge case of the power lok is definitely stronger.
One draw back is that it is a two piece design, and often comes apart.
Taking a few measures to prevent his is a plus. Using hardened bolts that are safety wired is not a bad idea:



Now the ramp design of the power lok is far superior in that instead if using a spring (like the "Z" spring) to apply tension to the clutches, the power lok uses bellevue springs to apply slight tension to the clutches and side gears. Once slippage occurs and torque is applied from the axle, the pinion shafts move up the ramps in the case, and apply an even greater amount of tension to the clutch packs and side gears.
This can create an even greater amount of breakaway pressure thus providing a much higher torque bias.
Again this places a great deal of stress on the cross section of the carrier, and the stronger design of the power lok make this a superior unit.

Having several of them on hand is always a plus. You wont find me using a trac lok ever again:

 

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The Anti Yam!
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Discussion Starter #4
Awesome response, thank you. :thumbup

Is the triangular shape you see around the pinion shafts the "Ramp"?

Are the clutch disks "Dished" like I have read mentioned in a few other places?

If they are, why?

In your opinion, would a Power-Lok out perform a True-Track in a rear axle installation as far as torque transfer goes?
 

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I believe this clutch type limited slip is the strongest and most aggressive limited slip differential available from Dana Spicer. It is a clutch type unit using floating cross shafts that ride up on ramps in the case, so yes, the ramps you see when you look into this cross shaft window is the ramp you are asking about. When power is applied, the shafts ride up the ramps and load the clutches for a positive engagement. A Power-Lok will not lock up 100%, but it is a very durable unit that will hold up fairly well with tall tires. It can be rebuilt, and can be set up smooth or aggressive by changing the clutch design or stacking configuration. Power-Loks are easily identified by their 2-piece case. They are a very strong unit due to the 4 spider gear design that provides twice as many teeth to carry the load as a 2 spider gear unit does. However, the case bolts can stretch or loosen after severe use over time. (4 pin, 4 tab clutches) (factory).
That was taken from a discussion in another thread, that I made in another website.

Clutch configurations and materials can be used. Ive been messing around with different bellevue washers, and clutch materials. carbon fiber is cool to work with but makes the bias so high that the LS stays real tight.
I use these in Dana 60 fronts, and need the slight slip they offer. When the front tires catch some air, and I am still on the gas, the truck almost never land on both tires equally. Having some slip in the front seems to prevent, my axle shafts or lockouts from exploding.

Is this a better design than the gear type LS units?
I do believe that the power lok is a better design due to its modular clutch design, meaning that I can change the amount of tension in the thing by using different clutch materials, or springs.
Im not sure too many of the other LS units will permit me to change the tension like this.
That being said, the Power lok is quite the LS unit, and is number one in my book.

Ive busted about everything that can break in a dana 60 front, and I can attest for the strength and reliability of the Power lok.
Its something that i will be using until I can find something better, and for now, this is the number one.
 
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