I have a 1989 f-150 2wd 4.9l. Now I have always had a pretty easy time in snow and looked in my rear view mirror as i was giveing it gas and spinning the tires it was eating both wheels for the intire time i had it floored. I was wondering if my truck might have a posi track system in it because after about a certain speed if the tires are spinning both well get power and get out of just about anything. I also have really grippy mud terain tires in the back so when they spin they usually get traction by digging deep. By the way my truck is a frankienstein truck that was a manual and now has a c-6 tranny that came out of a 3/4 ton pickup. So it very well could have some other kind of axle if theres such thing. So what do I got.

 

you probably have a limited slip rear end...i do believe that is the right thing im thinking about. I just know that there is a rearend that at a certain rpm both tires start spinning. When you light em on on tar or something can your hear a clunk kindof in the back?

 

yes and it hardly spins on dry old payment but on slick new payment it well eat both and do a complete donut. I mean it will wip around faster that you would believe.

 

I know it also sounds stupid but I am in the process of putting a 2inch lift on my truck and I take it mudidng around my town and never gets stuck as long as I dont have to stop in the mud hole I will always make it out. It seems anyway so far but then again I'm not takeing it in real agressive mud but on trails I'm all bussiness. LOL

 

Prier knowledge Tells me your truck, (if rear end is said to be stock) is a common 8.8, 3:55 Gears LS (Limited Slip) Rear. Being Able to Catch both tires Isnt uncommon, You will find that switching to 2nd gear when becoming stuck, or Roasting the tires will Cause both rear tires to break loose. You will most likely find that Reverse will Catch both tires as well depending on how you drive. and how bad you beat on your truck.
Well thats my 2 cents. Hope it helps!!
-Way

 

easy way to remember,


open differential is just that, open. since your inside wheel goes a shorter distance than your outside wheel when turning, this setup is more economical for every day driving. the easy way to remember this is that it sends equal power to each axle, NOT equal speed.

limited slip, or "posi" (which is a type of limited slip that GM used and the name just kind of stuck for limited slips in general) transfers equal torque to both wheels when under stress, but is light duty enough to let an inside wheel spin freely thus saving your tires from the pavement.

lockers, on the other hand, are open when not engaged, but when engaged, are 100% locked. meaning the wheels move at the same rate, not matter what. they have automatic (that engage when one wheel starts slipping and usually 'clunk' when locking) and on-command (that are either electrically locked or air locked)

and a spool locks both axles together. period. lol.




im sure thats more than you wanted, but i got carried away. lol

 

so to answer your question, its probably safe to say you have a limited slip, or "posi".

 

Open your driver's side door, look at the sticker on the doorframe. Write down the transmisson code and Look here:

http://www.drivetrain.com/Fordtrkratio_posidata.html

 

not going to work.

and yes, there is such thing as a "other kind of axle" lol

 

Right, didn't see the "frankenstein" comment..