alright guys im going to just plain ask this question and I feel like a retard for asking it. Im going back home for xmas and a buddy says he has a 9" that is has 3.00 gears and a posi. I would love to pop the carrier out of that axel and put in my truck that is geared with 373's and is an open diff. How can a tell if its a posi. thanks guys. I dont think it should matter, but the axel with 3.00s came out of a 77 f150 and its a 9" rear, and its hopefully going into a 66 f100 with a 9". The carriers should both interchange right? Im pretty sure the axel from drum to drum is a different size, but the carries change out.
Most Fords have a Traction-Lock, though it could be a Detroit Locker. Found this through a Google search: http://northeastoh.ebaycl***ifieds....spline-traction-lock-posi-carrier/?ad=4006599 The later one could be 31 spline...yours is likely 28, unless someone changed it. In other words, you may need axles to use it.
A 77 Ford truck rear. It a good chance it has 31 spline axles. If your rear is a 66 It a good chance it has 28 spline axles.
As Ratmotor said, to be interchangeable, both axles must be either 28 spline or 31 spline. 28 spline axle shafts can be ID'd by looking at the center brake hub area; a big rectangular slot in the center usually indicates a 28 spline axle. 31 spline axles usually have one small center chamferd hole and two outer holes (one on either side of it). Take a look at the pictures below: Ford "trac loc" rearends ("posi" is a GM term) have recessed bolt holes on the spool connecting it to the ring gear, 5/8 bolts, and a rough cast appearance. Ford open rearends have flat surface around the holes, 3/4" bolts and the spool is smooth. Everything you need to know is here: http://www.kevinstang.com/Ninecase.htm
thanks for the pictures gary. my 66 has the two circles in the axel so its a 31 spline. Im going up to MD in two days so I should know about the other 9" soon.
I'm not sure where this info comes from, but I have a half dozen 28 spline 9" rears in my garage with the 3 hole ends. I've rarely ever seen one with the rectangular slot. Could be that all the rectangular ones are 28, but the 3 holes doesn't mean 31 spline.
As long as you're pulling the 3rd member out, you can tell if it's an LSD by looking. The Ford LSDs were typically closed (can't see any of the internals). If you look and can see all the gears and a cross shaft in there, it's probably an open diff.
Like Just Gary said, on a traction-lok the ring gear bolts are countersunk in a raised clutch cover. On an open the bolts are on a machined flat surface. And the limited slips are known for cracking the clutch cover between those countersunk bolt holes, so be sure to check for that before you get too invested in it.
If your truck has 28 spline axles and the traction-loc is 31 spline, you can just swap out the 31 spline spider gears with 28 spline gears. While you have it apart you should replace the clutches.
when I grab up the axle ill take pictures and do more reading. Im getting it for free so it wont like illl be out anything but time. and i sure do have alot of that
if the 9" still has the ID tag check the first series of #s in the bottom row it will tell you the gear ratio and if there is an "L" in this line it is a limited slip and as far as i know all limited slips are 31 spline
its just semantics, if you say posi everyone should know what you are talking about. The restorers and the dealership parts counter guy have a problem with everyone calling everything by the exact terminology. I have a Detroit Locker in mine, I'm not sure what to call it maybe one of you fellas could help me out. Your question isn't dumb and you have good information to go by. As long as the spline count is good you should be good to go.
A quick check without taking it apart is to turn one axle and see if the other side turns in the same direction. If it does you have a "posi" rear end, if it turns opposite direction you don't.
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