I have an 04.5 2500 with a 11.5" rear with 3.73 gears and anti spin according to the glove box. I had my truck up on a jack, or one rear tire was, in the garage tonight and was working on one side and the tire rotated freely, the manual trans was in neutral. My question is are these clutch packs where I shouldn't have been able to do that or do they have a locking type that takes more spin or drive coming from trans to make the lock engage? Then how do you check that they are operating properly, as I notice in the snow sometimes I have 2 spinning and sometimes one. I think its working (as going down the road in the snow in 2wd a little bit of gas seems to make them both spin for a nice tail wagging) and all but that suprised me tonight.

 

No clutches, it is a gear type LSD.

 

Cool, thanks I had a nother brand truck before and they used the clutches had it rebuilt once and they seemed to wear out very quickly.

 

they are apparently a variant of the detroit true trac.

if you google it, you will see how it works...

 

What most others have stated, most use torque input (pinion) to actuate the "posi" it will put more pressure on the pack, make both wheels spin. you can still have a one legger even with a posi.

Most lockers when you have any input fromt he pinion, it locks, that's it, one wheel up, down, it's locked. Unless you break an axle, both wheels wheel spin, same speed, ect. This is true around corners and all (unless your free wheeling) but it will still scuf tires bad.

 

They don't have clutches, instead they use a set of shoes on conical side gears that brake the faster spinning axle and transfer the power.

Not a gear type either as without the brake shoes you have no limited slip and they act like an open diff.

 

I have read in the past if your one wheel is spinning gently touch the brakes on and off and that'll get them both going.
I don't understand it but this is what supposedly works.

 

Exactly since it's a "torque Biased" system, it will spin both wheels if there within say 5% load difference (psi, whatever you want to measure) Put one on ice, one on concrete and floor it, the ice will spin, you'll move, but not as fast. A locker will either break the axle, or smoke the tire on the concret.

Hitting the brakes helps equilize the load, so it will work. They teach hum vee drivers that too, you can do it with an open rear if you get it even. A lot of people expect a locker out of a posi, and expect a posi driving charicteristic's when they have a locker.

If you want a locker, put a spool in it

 

Have you even driven a vehicle with a properly functioning Detroit in the rear? Judging by your post, I would say you have not. While I agree a good LSD is the way to go for the street, to imply that an auto locker will function like a spool is way off base.

 

The 06 Dura/ally I had a nice locker in it. You could get it all twisted up, one tire really light, it would clunk, and be locked solid. Really nice around the farm. But not good for burnouts or playing around, it would unlock at around 20 MPH.

 

Yes, I was more refering to the lockers designed for off road use (not the streetable lockers and such), since most don't (drivers) "free wheel" around hills, rocks and such. Most of the turns I'm always on the gas so it scrubs the inner wheel, however coasting would result in the inner wheel unlocking (always wanted an air locker, but never had the money for those). But like you said the locker in my voice was for off road, so I don't really free wheel when going up and such. I do understand the newer lockers, GM's and such are much better designed for the street, while still being better for off road than a limited slip

Personally if I had the choice in this truck, I would love to have the limited slip type front and rear, with the option of locking both. This truck is mostly street 95%, where as the bronco was 99% off road So on road manners to say the least were not great (hence the mention of a spool instead of a locker) In my case a spool would have been just as good, and a lot cheaper than the locker. Again all off road was my basis

 

Well, you are sort of right....A traditonal auto locker (like a Detroit) freewheels the outside wheel around a corner and the inside wheel propels the vehicle - the exact opposite to an open diff or LSD. The amount of force acting on the locker is 100% irrelevant in regards to whether the locker engages or not. Simply put, if one wheel rotates about 1/3 more than the other, the diff will lock....under power or not, does not matter. Now, send enough power to the wheels in a corner for one to bust free and rotate that 1/3 more than the other and the diff will lock and act like spool in that moment. Don't do that, and you will be fine. That said, depending on the application, the potential for somewhat unusual tire wear does exist with this type of diff because of the inside wheel driving the vehicle around a corner instead of the outside wheel - but it is still not comparable to a spool. This is an especially poor choice for a diff on a vehicle in high load conditions on the street (like our trucks towing a heavy 5ver) where it is very beneficial to have the outside tire propeling the vehicle around a corner.

What I would really like is to have a Dana Powr-Lok in the rear again - that is one thing I miss about the 2nd gens. The LSD in the 3rd gens sucks compared to the Powr-Lok.

 

yeah, so far mine has been good to me, but compared the ole mans 99, that thing will light both no matter what. And I agree, lockers are more based on tire rotation vs input torque. But like you already mentioned for our trucks something a bit more aggressive would be best (but not locker) One thing I like about the clutch packs is they are always working. I've heard the GM's only lock if under 20mph or something? (cyntrifical?) I'm not 100% but I do know.

It would have been nice if at least they offered the e lockers in our truck, that would have been nice. Def. worth a few hundred extra too, I'd have paid