i have no idea about rear ends. i know only 1 tire spins on my truck, so i think that's called open right? is it possible to make it so both tires spin, and will this affect the gas milage?

 

Differentials are very hard to explain without diagrams, so your best bet at understanding the inside of one is to go to the library or look it up on howstuffworks.com. That said, I'll do my best. Inside your diff is a set of gears that allow your wheels to turn at different speeds, hence the name, differential. This allows you to go around corners without your tires squeeling, as one tire would have to drag if both tires were forced to turn the same amount. In a straight line, torque is divided equally between the wheels, and so technically, both wheels are propelling you. The problem arises when one wheel has substantially less traction, and by the design of the diff, all the torque goes to this one side. This "open differential" as they call it can leave you stranded, as the wheel without traction spins and the other one just sits.
There are a few ways to remedy this, but they'll all take a chunk out of your wallet.
The first is a limited-slip. This theoretically puts enough friction between the axles that they don't want to turn at different speeds. This is a streetable option and does not noticably increase tire wear. The catch is, it always seems to not work when you need it.
You can get a Detroit Locker. These lock both axles together until you hit a corner, when it unlocks because of the torque difference.
Your best option would be a selectable locker, like an Ox Locker or ARB. These leave your diff open 'til you hit a button or pull a lever, and then it locks up your diff so both wheels turn.
Finally you can get a spool. This is a permanent locker. I personally don't recommend it on a vehicle that sees mainly street time. This increases tire wear and makes for difficult cornering, especially in inclement weather.
Hope this helps, again, I'd recommend a visit to howstuffworks.com.

The Law

 

ah! ok cool. now im understanding. ever since i got stuck in my buddies driveway (long stupid story) it been bothering me cause if i had both wheels spinning i could have gotten out no porblem. the one that didn't turn had all the traction in the world.

so you know how much a detroit rocker would cost and if i can install it myself?

 

Vamp-

Seems that they usually run $400-500 American new, just for the Locker itself. I did a quick search and found this site:

http://www.trailquest.com/lockers/detroit.shtml

You might be able to find someone selling a used limited slip for a decent price. That and about 300-400 lbs in the truck bed will make a lot of difference.

Hey Law, good description!

Jayson

 

Hi Law, excellent description, you should write shop manuals.

 

Vampiro,

I just installed a mini-spool in my 9" on a 78 F150 ($26.00 on ebay). It's not my daily driver, mainly off-road and maybe snow plowing. In theory, you will have more tire wear than normal, but those that actually have a spool or mini spool say it's barely noticable. Cornering in the snow/ice will obviously be worse with a mini spool, but no worse than with a detroit locker (since there won't be enough torque to unlock it). That's why the selectable locker would be best (and very expensive).

Look for my old post in this forum "this is a mini spool" and I have pics of the spider gears of an open diff and a mini spool. I also have pics of it on my website. www.brayarch.com/~kevin/truck/78f150.html

Kevin K.

 

Writing manuals, now that would be an awesome job. I have such a fascination with all things mechanical that even my most truck loving and understanding buddies find it a little creepy that I know so much. In this particular case I did a little research 'cause I myself am tired of getting stuck at inopportune times. I have the factory limited slip that seems to work in parking lots, allowing some squealing, and then act like a normal open diff the moment anyone suggests a terrain other than asphalt. Like Vampiro, I too have experienced the shame of being stuck in a driveway.
The day they come out with Ox Lockers for the TTB Dana 50 and Ford 10.25", the place to find me will be under my F-250, covered in gear oil, diff parts laying around me, with a huge smile on my face.

The Law