Posted by Nay on March 26, 01 at 09:11:42:
In Reply to: Re: Lockers posted by andrew on March 25, 01 at 17:44:47:
That is not correct. The Detroit Softlocker is an automatic locker that is locked full time. It will *only* disengage to allow wheel speed differentiation when you coast - it will re-engage the instant you are back on the throttle. If you like to mash the gas for passing, you will need to expect the rear end to push the front, causing moderate understeer. You will feel it heavily in any tight turn as it forces one tire to scrub, unless of course you can coast through u-turns.
Full automatic lockers are for offroad use. If you are not into hardcore fourwheeling (something of an oxymoron with a vehicle as big as a Suburban), automatic lockers would be a strange choice. The benefits of the Detroit are that is is pretty much indestructible and there is nothing to wear out. They also have a lot of built in backlash to allow proper operation, although this is felt less with an automatic transmission.
Back to the conversation on the Eaton - this is not a locker. It is a limited slip. Any device that is "open" in the normal state and uses clutch packs to transfer torque is a limited slip. These units typically work well for road use and moderate fourwheeling. The downside is they will wear out as the clutches are a wear component.
Limited slips never act like a locker. They are torque biased mechanisms that, depending on factors such as preload, can transfer a certain amount of torque to the wheel with more traction. Clutch based limited slips have a preload that must be overcome to allow differentiation. They are not actually "open", but rather can allow limited amounts of slip (wheel differentiation) as the name implies.
A typical factory limited slip will have a fairly low bias, while a typical aftermarket bias is 2.5:1. This means the unit can transfer 2.5 times the torque of the wheel with traction to the one that is slipping. The problem with this is simple: if one wheel has 100% of the traction, then the wheel that is spinning is getting 100% of the torque. And 2.5 times 0 still equals zero and you are no better off than if you had an open differential. Modulating the brakes can help keep one wheel from getting too much spin and keep the unit within its operating range. The Detroit locker (or any automatic locker) will force 50% to each side no matter what, although in very slipperly situations that usually just means you will slide sideways.
The best limited slips are the gear driven systems like the Zexel Torsen and Detroit True Trac. These units have no clutches to wear out and are entirely gear driven. The Torsen is what you find in use in Audi's All Wheel Drive as a center differential. The problem with these is they are not typically very strong as gear teeth create far less contact than clutch plates. I'm not sure I'd put one in a 14 bolt behind 300+ lb/ft of torque, and for that matter I doubt they are available for that application.
I am personally a big fan of the Auburn unit (www.auburngear.com), but I have never run one in a Sub. They are very strong and work exceptionally well in all conditions I have experienced, including hardcore fourwheeling.
As far as cost goes, you might as well look to the best aftermarket equipment out there. Installing a factory unit will still require replacement of the open carrier and reset of the gears. This is the exact same thing that has to be done for any other unit that is a carrier replacement. All limited slips fall into this category. There are "lunchbox lockers" that are available for use with your stock carrier, but then you are sacrificing strength for lower cost, something I consider to be contrary to the idea of having a better differential.
Nay
: the specific locker that I am looking at is a Detroit soft locker. From the information that they supply I am getting the ideal that it only engages when there is wheel slipage.
: You can see the one that I am looking at by going to:
: http://www.hill4wheeldrive.com/cgi-bin/products.cgi?category=category17&item=3487537905
: let me know what you guys think!!