nickleinonen

that might have been true with the dana's, but with the new AAM axles, there is no plate clutches in the differential. there are the 2 sides gears, then 6 pinion gears that press against 6 brake shoes. the more speed differential between the 2 side gears, the more force gets applied to the brake shoes to try and maintain a constent speed between the 2 side gears. i have a pic in the my members gallery [link on left, not one in sig] that shows a screen grab of the arangement of the rear differential from the service manual

N_Tillett

OK - I stand corrected - the most common positracs have generally been either flat (other spicer, division of DANA) or cone shaped (Auburn locker) clutches with springs (usually wavy washers) to preload them. Whatever the case, one that is not posi or limited slip - or what ever generic name you want to call a device to apply a limited additional torque to a slipping wheel - the non-posi types ARE NOT ONE WHEEL DRIVE! THEY ARE NOT LEFT WHEEL DRIVE! there is a differential to apply equal driving torque to both rear wheels under most conditions. What I am really getting at here - is that the people that are saying they have one wheel drive or left wheel drive are way off base. That concept is entirely wrong!

Nuff said.

As for this design - looks like an improvement - I had seen some like this in the aftermarket a few years ago - they were expensive but really popular in the rock crawler crowds - nice design.

I'd rather see half the people that get out in ice and snow and can't drive on it stay home anyway. (You know the ones I mean - The typical type that you see spinning one wheel at 90 miles an hour to melt a path to pavement and get a push - that think if they can go 60 miles an hour on ice, they should be able to stop on it too!!!!!)

possum

So with all that I jacked up both rears this afternoon and gave one wheel a spin and the other side spun the opposite way.
Doesn't that mean I have limited slip? Like one of you said as long as you know what you got back there it helps in making some driving decisions. so perhaps I was wrong thinking I had a lefty drive Great responses thanks.

nickleinonen

sounds like an open rear end to me..

http://auto.howstuffworks.com/differential3.htm

in the above link, you can see an animations of an open rear end. if you click the turn button in the animation, you can see the outside wheel turns quicker than the inside [which is almost stopped for the animation] now if you were to stop the driveshaft and keep the outside wheel turning, the inside wheel would need to rotate in the oppiset direction to keep everything in sync. if you can turn the one side and the other side turns oppiset direction, it is an open diff...

although i have never tried this on the new aam tracrite lsd's so i am not sure how it reacts to being spun by hand like you did.

rockhound

i live in ice and snow country. about 8500 ft in the colorado mountains

i wouldn't own anything that didn't have a locker or limited slip in the rear. yes when they do break free i can be bad but you are less likely to break free in the first place. and less likely to be stuck. and when you are stopped on a icy slope with a loaded trailer they are nice to have, getting that load rolling safely is so much easier

i have never had any of my trucks break free while rolling along in the proper gear and speed for the condition of the road

bottom line slow down. you'll live longer

omaharam

UM..? So your opinion is that an open diff is just as good or the same as a limited slip? THAT concept is entirely wrong. I understand that SOME forces may be transferred to the other axle, but, there is nothing ( clutches or whatever ) that is actually forcing a load transfer in an open diff. For traction capabilities a limited slip of some kind is far superior to an open diff. If you mash the long peddal in any vehicle with excess power , one with an open differential will spin only one tire, leaving a streak of molten rubber. If you have limited slip in the same vehicle with the same power, not only will it leave tracks from both tires, they will be shorter tracks as well. You are applying torque to both axles and so the load splits resulting in quicker "hook up."

omaharam

I have a story that counterdicts the above opinion.
I have a 31' travel trailer that I took camping just last week. Of course when we arrived Friday evening it was raining . The camper total loaded weight was probabyl about 8500lbs and I had 4 adults, 1 child, and two small dogs on board. There is a hill in the campground that is fairly steep. I had to stop on the hill to wait for some bozo to get out of my way. I started to push on the long pedal, and the right rear began to spin. I let up. I ever so slightly eased on again, thinking I could get her movon'. Nope. I tried four times before I put it in 4wheel. Yes, I understand that is what 4wheel is for and that it got me out of my situation. However, having had many vehicles with open diffs and limited slips of various kinds, my opinion is that if my truck had "anti-spin" I would not have had to use the little cheater **** on the dash.
If you are familiar with driving a vehicle with a limited slip, you should have no problems. AAsuch an axle set up has NEVER gotten me into trouble. Yes it handles different if the rears start to spin, but, if you know what to expect it is very simple to control.

1sttruck

"For traction capabilities a limited slip of some kind is far superior to an open diff. If you mash the long peddal in any vehicle with excess power , one with an open differential will spin only one tire, leaving a streak of molten rubber. If you have limited slip in the same vehicle with the same power, not only will it leave tracks from both tires, they will be shorter tracks as well. You are applying torque to both axles and so the load splits resulting in quicker "hook up.""

After 'hooking up' you get the characteristic rear end breaking loose on surfaces of uniform traction, whether it's high power and dry road, or rain or ice covered road, and sometimes it's recoverable, sometimes it's not. The open diff 'fails gracefully', just spinning a tire. I think that almost everyone agrees that it's easy to break to break the rear end loose with a limited slip, unless the suspension is set up properly. What seems to be in question is whether it's desirable to have the diff making the decision on when to engage or not engage the limited slip, and whether the risk of the rear end coming around after breaking loose is a worthwhile tradeoff.

I can think, I know when I need more traction, and it's very, very easy for me to snick the truck in 4wd if I have a problem. I would prefer to also have a selectable locker as a 'layer of defense' in low traction situations, but I'd also accept a high bias limited slip that would only engage if I use the brakes. What I don't want is another 'automatic' contraption, especially one that puts me and my passengers at risk. The biggest concern is ice in the winter, as when it's below freezing around here one can never know where there'll be ice; running across the road, on a bridge, filling the ruts in the road, in a low spot, etc.

Last year we were tooling down I5 heading into Portland, and all of sudden a car a ways up ahead starts doing 360s and ends up off the road. We hit the edge of an ice storm. I slowed down from about 60 mph to 50 mph, and looking around there were vehicles in ditches on both sides of the road, one upside down with a patrolman looking inside, and cars wiggling as they went down the road. I pulled over at the next rest stop, aired the ties down a bit, put it in 4wd and headed off, not going over 50 mph. As I got closer to the house the only vehicles out were chained up, and I eventually had to chain up as even with the studded tires the truck would started sliding after we had stopped to let a truck try to pull a car out of a ditch. The open diff behaved like I wanted it to, just spinning a tire once in awhile, and not careening across two or three lanes on I5. It was a bad storm as I84 was closed for awhile, and when it opened it was chains only for all vehicles, as it was on I90 north of the area.

TAS05CTD610

All an all said you can break a posi rear up too. My sister has a Blazer and if you mashed the peddal around a turn, it would clunk and spin one tire (and it had a posi) I love posi rears and opens. They both have advantages. If all you do is haul on the highway, open is the way to go, better tire wear, etc. Posi's or limited slips are good if you ever launch a boat, go up a hill, take off road, snow, anything. You can drive a open rear just as good as a locker (as a few of the knowlegable guys said) A posi works off of pressure equilization. If you spin one wheel in a truck that has a open rear, step on the brake. once the brakes put the same amount of pressure on each wheel, both will spin (this is after all the concept behind a posi). You can drive either or just as good as one another. yes if you smash the long pedal, you will light one tire, vrs a posi, but the fact is you can light both tires if you hold the brake. Anything and everything is possible if you put your mind to it. Man can fly, just nobody has thought of how yet