Vintage Mustang Forums banner

Identifying Posi

569 Views 4 Replies 2 Participants Last post by  camachinist
Whats the best way to see if a rear end is posi? I heard you just jack it up and turn one wheel the other will go the opposite way? I'm going to be looking in junk yards so are there any ways to tell just by outward appearance,
thanx for your time

1970 351 Cleveland Mach I
First car, bought it in 8th grade, I'm now 17 and it's
loads of fun
1 - 5 of 5 Posts

· Registered
7,478 Posts
The way I identify a posi, when you turn a wheel, the one on the opposite side will turn in the same direction. These days, the 9" posi's from a car are almost impossible to find, look in F150 4WD pickups or big Broncos.

Required tools for operating a Vintage Mustang:
1. Duct Tape
2. J.B. Weld
3. B.F.H. (Big Fat Hammer)

Discussion Starter · #3 ·
If it is a factory posi. The door tag will have a letter instead of a number
for rear code. Junkyard people are very unlikely to have a posi slip through
thier system without knowing it. In general they will show up in cars that have
been hot rodded by kids. In station wagons. In cars with trailer hitches. They
are also in Shelby mustangs that have been hidden in barns. Out here in Oregon
hardly a day goes by that some kid doesn't come by and ask if I don't have an old
car in my barn.

M.C.A.# 50000

· Registered
10,537 Posts
Jack up one side only with the car in neutral and attempt to turn the jacked up wheel with a torque wrench on the lug nut....if it's a posi, it should take 30 to 40 lb ft to turn the wheel.

Or, if the car is up on blocks, turn the pinion while holding one should be nearly impossible to turn the pinion by hand if the car has a posi....and the wheels will turn in the SAME direction...

1 - 5 of 5 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.