Posted by Nay on March 26, 01 at 13:46:00:
In Reply to: Go Detroit posted by Marty on March 26, 01 at 10:51:25:
I think you misread my post - I was not pitching the Detroit as a spool. The torque loaded state of an automatic locker is locked 50/50. It has to unlock to allow differentiation, which it does *only* in coast mode. It does not lock when it "detects" wheel slip; it unlocks when you let off the gas. I was responding to Andrew who stated that from the website he was looking at the Detroit would only engage when there was wheel slip. That is categorically incorrect. There is no such thing as wheel slip with a Detroit. The Detroit will allow differentiation in coast mode. You have to completely lose traction at both wheels to get wheel spin.
I personally think the Detroit Softlocker is one of the best things out there because it is automatic, as positive as you can get, and virtually indestructible. I like really strong products that work automatically and you can install and forget about. But I don't run them because I have to deal with winding mountain roads at high elevation in bad weather conditions and can't afford to have a Detroit rear (or front) pushing me around if I am not in a situation where I can afford to coast. You can't always coast in emergency situations, and if you need throttle to maneuver than you are locked 100% just like a spool (better to have the spool because at least it is predictable - you get the same push every time, whereas the locker will be switching modes on you).
Eaton is being clever with their use of the word "locker". If you read their writeup, it is not a torque sensing mechanism as the limited slip is traditionally defined, but rather requires wheelspin to "engage". This is the same concept as the viscous coupling system used in some limited slips - the wheelspin increases viscosity and locks the axles. But these systems force you to lose traction before it will do anything, and anybody who plays in very low traction conditions knows that once lost traction is often difficult to regain. To put it another way, the Eaton unit will not function the way a true locker functions, which is the only reason GM can offer it from the factory. If it can act like an open diff...well...then it can act like an open diff. If it could automatically be both an open diff and a locker in any situation then every fourwheeler in the world would run GM axles with Eaton differentials.
Tractech (Detroit) is doing the same spin doctoring as Eaton with their "Gearless Locker", which also uses clutches to "lock" the axles. If you read any writeup on the Gearless, you will basically read that it works like a limited slip because essentially it is. That doesn't make it bad, and it may well work better than most factory units (the Dana Traclok is useless offroad unless you shim the clutches to be far more aggressive, for example). You are right that the Auburn will eventually become a paperweight and is not rebuildable. But hardcore offroaders don't choose the Detroit over it for that reason, they choose the Detroit because it is a full locker and the Auburn is not a locker at all.
I am not pitching one way or the other. Everything has advantages and disadvantages, and a Detroit has huge advantages in many situations. My perspective and therefore opinion on the whole thing is this: I wheel hardcore on 4+ rated Moab trails and the like with only limited slips on both ends (Auburn Rear/Tru-Trac front). I go anywhere the guys with automatic rear lockers go, and often with less struggle. And on the drive home, I don't have to "coast" just to go around turns, something that would personally bother me. The situations in which I would actually need a Detroit are 1) completely avoidable, and 2) comprise maybe one tenth of one percent of all driving with focused hardcore offroad use. I don't make choices to meet the .1% need over the 99.9% needs - others build specifically to the .1%. I don't think there is any right or wrong in either choice. But, I've spent thousands to not have to *need* lockers (gears, suspension, etc, etc). In a Sub that sees the dirt, a Detroit should be given a lot of consideration, because it is many magnitudes cheaper than a front axle conversion, low gears, and high travel suspension, all of which can make you wish you *had* the road manners of just a rear Detroit :^).
Nay
: I think your comments are a little off the mark, Nay.
: If automatic lockers were locked full time they would be called a spool. The true lockers available these days do differentiate/unload when coasting or turning. Gone are the days of wheel hop under mild street conditions.
: Don't ever expect a Suburban to turn tight enough to engage a locker. Won't happen unless you spin a wheel. Besides, why would you even try a tight u-turn with anything more than just-over idle? If you are hitting 20, you better have more than 50 feet before the curb.
: The Eaton unit is a 'locker' that allows greater differential action (slip) before positively engaging the locking mechanism. Doubt it? Go to the Eaton website.
: Auburn is a good limited slip. I question whether the unit can be rebuilt. I had heard that was the reason most 'hardcore' offroaders do not prefer it over Detroit or Powertrax products.