Force on the cross pin wedges the inner (touches the cross pin) and outer (is what the axle shafts slide into) plates of the locker toward each other (preventing the wheels from spinning at different speeds. For the plates to line up and engage you've gotta turn the tires at different speeds 1/16th of a turn or so. For the tires to keep spinning at different speeds the teeth of the plates need to overcome the force on the cross pin to allow the teeth on the inner and outer plates to jump over each other. However, the design of the locker is such that the wheels must be spinning at the same speed (driving straight) before this can happen. This is why lighter vehicles with deep gears and short wheelbases tend to chirp tires through an entire turn or get the ratcheting clunk and smooth turning. Once it's locked it's almost certainly going to stay locked until there's no longer force on the cross pin so once you mash it you're chirping until you're off the gas or going straight.


In snow this can cause problems because it's much easier to peel out at every corner. Highly crowned roads don't help because instead of doing the one wheel peel you slowly slide sideways. You get used to it, it's still better than open by a mile. I generally drive around in 2wd in the snow and only use 4wd for hills, parking lots and anywhere else I need a little more go. An LS really isn't any better in this regard although it's going to be more tolerant of big changes in throttle mid-corner (e.g. on ramp). With normal street traction, 133" of wheelbase and the weight of a vehicle it's perfectly normal to make a perfectly smooth turn with light throttle application. Even in the rain I almost never chirp around corners with anything substantial in the bed.


I've actually got a lunchbox locker up front so we'll see how it does in the snow this winter. I expect it to handle like crap on the road but the traction should be worth it when in deep snow and off road.

 

Not exactly. Yes the force of the crosspin is what forces the inner clutches into the outer clutches to engage a lunchbox locker (a Detroit works the same as a lunchbox, but the mechanism is a little different), but all it takes to disengage one side is for the tire on that side to try to go faster than the ring gear. That takes all of the force off that side and it can disengage freely. Meanwhile the crosspin continues to push against the other side so it keeps driving the inside tire. The reason it tens to stay locked when you "mash it" is that the lightly loaded inside tire doesn't get enough traction to keep you going, so it spins. That allows the ring gear to go faster so it keeps up with the outside tire, locking that side and driving both tires. Any time the inside tire hooks up enough to stop spinning the locker will disengage. It's just that once the inside tire is spinning it's very unlikely to hook up until you let off or finish the turn.


I agree with everything said here (except that I use 4WD a lot in the snow, it not only helps you drive forward, it also helps a lot with stability (and even helps braking a little if you don't have ABS). And I'd go even father and say that a clutch-type limited slip is actually worse than a locker for stability in snow. It's not quite as abrupt, but I had way more trouble spinning out an Explorer with a factory limited slip than I did a CJ5 with a Detroit.

I did that one winter in my F-150. You can not drive on a snowy freeway with a locker in the front axle. The first lane change I tried, the truck jumped abruptly about 8 feet to the left! (good thing the lane was empty!). The problem is that when the left front tire lost traction, the right front not only gave the typical torque steer, but it also tried (very effectively!) to turn the steering wheel in my hands. I thought I was ready for it on the next lane change. On that one the truck only jumped about 5 feet. I shifted out of 4WD and never used it on the highway again until I got the front locker out. If you only use 4WD at low speeds it's just really annoying (but probably still worth it for the benefit). But at high speeds (above about 40 mph?) it's ridiculously dangerous. That's why I will never put an automatic locker in a front axle again.

 

I have the Detroit true trac up front in my 88 F150 also and everytime I am in 4wheel drive and start turning I can feel the truck hop like but that is always only up to 25mph. I have never used 4x4 on the highway for 2 reasons. 1 I haven't gotten that bad of a snow yet up here while driving this truck, 2 every snow there is there is an accident at least every 5 miles so the cops are constantly slowing people down. I do have to say that with it hoping like it does at low speeds on the backroads (in the mud and some snow) I would say Bob (Nothing special) would be correct about how violent it is.
Trav

 

Have a Detroit in my F350. Have never regretted installing. It works,all there is to it. Only negative is increased tire wear.

 

Is a truetrac worth it if you already have the factory LSD rear?

 

Honestly depends on a few variables. Is your stock lsd worn out? Do you ever need added traction more so than an open rear could offer? How much money do you have lying around?

Truetrac is clutchless, it never wears out, and offers far greater "one wheel" drive resistance over factory LSD.

 

I go in the mud every once in a while...would be more often but it hasn't rained enough here...I don't know if my LSD has worn off, I still see a lot of strange rainbow colors so my LSD might still be in my system(;

 

Personally I think a factory limited slip is the worst of both worlds. It tends to make tires scrub in corners whether you're on the power or not. In my experience that gives worse stability problems than a Detroit. It also isn't particularly positive, so when you really need it it doesn't seem to give as much help as is needed. That's in factory form. A worn out unit won't be as bad for stability but will be worse for traction, while an aggressively set up one will give better traction with even worse stability. But I will admit that a lot of people have a different opinion of them than I do. I'm not saying they're wrong, just that I don't agree.

On the other hand a Truetrac only hurts stability when you give it gas, and even then, the only diff that's better for stability is an open diff. So they can be set up pretty aggressively without hurting stability, and they will put a lot more torque to the tire with traction in most situations than a factory limited slip. Plus it won't wear out.

 

But is a little bit more traction worth $1000?

 

Lunch-box lockers are ~$300/axle after shipping. Add $20 for a jug of Walmart gear oil, a gasket and sealant.

 

Did not know that! I thought detroits were almost always $800 to do each axle if you're doing the labor yourself, which I'm not even sure I could do myself.

 

Lunchbox lockers are the kind of thing you can do after watching a YouTube video. Gear setup is not required. If you're paying someone else to install them then you're doing it wrong.

 

Where exactly are you finding lockers for that cheap? Even the Spartan exploding lockers are $400 before shipping. And Torq Master doesn't make a locker for a 10.25 diff.

 

I have a Spartan I put in back 4yr ago for $300 (IIRC) off Amazon and I bought an Aussie last year for $250 on eBay (new) and installed it last week.

 

Right, Torq Master makes the Aussie lockers, but not for 10.25 axles. And Spartans have, evidently, gone up in price.