Ford Muscle Cars Tech Forum banner

1 - 4 of 4 Posts

·
Registered
Joined
·
2,301 Posts
Discussion Starter #1
Yeah, finally I have a truck in my life again. It is a 79 F-150 Custom that was a father-son project done about 10 yrs ago. Seller tells me it is currently running a 302 crate motor, longblock rebuild to stock specs. It is a 4x4 with one heck of a granny gear. It originally had an inline 6 in it. It currently had a 9" rear but only one tire brakes loose in the gravel. My question is, were 4x4s made with a peg leg rear from the factory? Of course the tag with all the codes is long gone, as is the warranty tag due to it getting a new issued vin because of a repaint and restore. So, I was just wondering what was gonna happen if I use the 4x4 option? One rear wheel and 2 front wheels? One front and one rear wheel? No wheels? Oh boy here we go.
 

·
Registered
Joined
·
10,299 Posts
Open diff's are actually common on 4x4 trucks. Figure that it's still twice the powered wheels of an open-diff 4x2. Yeah, whatever. :rolleyes: It's also had many years to be changed, and it has if there is no tag. Double-check the door tag (decal) for the original axle code.

Otherwise, I would test it. Just chock the front tires, throw it in neutral, and jack the whole rear axle up. Turn one tire. The other tire will spin the opposite direction if it's an open diff. It will spin the same direction if it's any type of limited-slip. If it does, then the LSD is toast and needs a rebuild or replacement. Most are fried by now as most folks don't realize what damages them, and 30+ years later, it's the most common situation.

LSDs are very uncommon in the front diffs from the factory, but you may as well check that one too, just to know for sure what it is today.

David
 

·
Registered
Joined
·
477 Posts
I'll add that I have seen Traction locks with the clutches/preload parts so worn that they behave like an open diff when performing the "wheels jacked up" procedure David refered to.
If your truck still has the original hoghead in it,it should have a fill plug on the drivers side. By removing it and using a flashlight,the ring gear bolts can be seen. If the bolt heads are 3/4" and the carrier flange is flat,it's an open carrier. If the heads are 5/8" and sit in a recess,you have a (worn out) traction lock.
 
1 - 4 of 4 Posts
Top