73 mustang posi , how do I do it

I wanna put a posi on my 73 , just how do I go about doing it , change the whole rear end or just the gears , 3rd member , im new at this and need some advice


Anyone ??

Easiest in my opinion? Find a center section that is posi (traction-lok) and replace yours with it. An original traction lok rear is going to cost you though. If you have an 8" or 9" rear your whole center section is removable with minor work on your part.

Is there repro, or aftermarket cheaper

This is something I have also always wanted to do. But it looks like te center section is welded in on my rearend, is this normal? The diff tag says its a non locking 3.25, I could go for some fully locking 3.73's and be done with peg leg burnouts forever!

Correct me if I'm wrong, but I thought you could put a track lock carrier inside any 9" rear end

Yes a posi differential can be added to any 9". Be careful what you buy as many if not most have 28 spline axles. If you pick up a 31 spline posi you'll end up buying axles. A posi should probably be installed by someone who knows what they are doing unless you're a pretty acomplished mechanic. It is one of the very few jobs I hire someone to do.

Yeah gunna have someone do it, so a 28 is the way to go or with a 31 i need new axels


Sorry if i sound like a noob just wanna door right


Do it, not door

My rebuilding experience has been on Ford 8.8. A 9 inch should be easier. To add a posi to your rear end, you can replace the center section with a used one that already has the posi in it, but as noted earlier, it's probably not cheap. Also, the used posi unit may be worn out and may need rebuilding anyway.

You can purchase an aftermarket posi unit from a number of vendors. Autorestomod has a lot of videos, in one series they did an installation of the Detroit Truetrac. You can check it out at: http://www.youtube.com/watch?v=LeWfDTZEW0Y.

I'd suggest checking out a crush sleeve eliminator to make installation simpler.

I'm not a fan of the pipe and hammer method of installing bearings on the carrier. A small press from Harbor Freight does the job nicely.

Bolting the new ring gear to the Truetrac diff carrier should be pretty simple. I wouldn't use the bolts to seat the ring gear. Put the carrier in the freezer for a couple hours, and the ring gear in a oven at about 200 degrees for 30-40 minutes or so. When you pull them out, the ring gear should slide right onto the carrier. I've always heard that you should use new ring gear bolts, and make sure they have red Loctite. I do.

Since you're reusing your ring and pinion gears, so they should be matched, but still double check your backlash and pattern before finishing up.

I hope that helps.

Thanks

The Ford 9" rear end is the single best rear in all American Musclecardom. Even chevy guys use them, and it drives them friggin crazy to admit it. Take a little time to learn about them and you will be happy to find there are a million suppliers of parts for them. On my original 9" rear i had a 28 spline, which is fine for anything short of 500lb of torque, and an open diff with a 2.75 hwy gear. Great if you need to go state to state at +90mph all weekend but sucked the rest of the time. I put in a Trutrac with 3.25's and its a different car. But, if it rains the car now will slide all over the street. Big difference from a spinning but controlled open diff. You can put 500hp thru an open diff with wide sticky tires and have a very fast car. Frank Bullet had an open diff on his 390 mustang. If you want use all of your engine but risk smacking something i like the Trutrac. Made for 28's and 31's....fits in all Ford 9's...dozens of suppliers. All you gotta do is buy the diff, pick your Motive gear set, and find some body to install it....or spend a few years learning how to set up gear set, because its easy to explain but usually gets done wrong. And once a gear set howls it is ruined.

Yeah gunna have someone do it, so a 28 is the way to go or with a 31 i need new axels


Sorry if i sound like a noob just wanna door right


Do it, not door

Click to expand...

You probably have 28 spline axles, but maybe not. You can pull one axle and double check the spline count before you buy your posi differential. If you're only planning to do this once, it's probably easier and cheaper to let someone else do it. You do need some specialized equipment, i.e. in-lb beam torque wrench, calipers, hydraulic press, and magnetic dial indicator and for that cost, you can probably pay an experience mechanic to do it. Good luck.

Yeah gunna have someone do it, so a 28 is the way to go or with a 31 i need new axels


Sorry if i sound like a noob just wanna door right


Do it, not door

Click to expand...

You need to find out whether you have 28 or 31 spline axles and buy the carrier accordingly

Here is a great sight that I have recommended often to folks wanting to learn about the Ford 9 inch.

http://www.kevinstang.com/Ninecase.htm

The Ford 9" rear end is the single best rear in all American Musclecardom. Even chevy guys use them, and it drives them friggin crazy to admit it. Take a little time to learn about them and you will be happy to find there are a million suppliers of parts for them. On my original 9" rear i had a 28 spline, which is fine for anything short of 500lb of torque, and an open diff with a 2.75 hwy gear. Great if you need to go state to state at +90mph all weekend but sucked the rest of the time. I put in a Trutrac with 3.25's and its a different car. But, if it rains the car now will slide all over the street. Big difference from a spinning but controlled open diff. You can put 500hp thru an open diff with wide sticky tires and have a very fast car. Frank Bullet had an open diff on his 390 mustang. If you want use all of your engine but risk smacking something i like the Trutrac. Made for 28's and 31's....fits in all Ford 9's...dozens of suppliers. All you gotta do is buy the diff, pick your Motive gear set, and find some body to install it....or spend a few years learning how to set up gear set, because its easy to explain but usually gets done wrong. And once a gear set howls it is ruined.

Click to expand...

Amen Brother.

Agreed the 9" is a tremendous rear axle, lightweight and strong, it is not very efficient however. In a comparison of several axles the 9" took the most power to drive. What makes it strong is the low location of the pinion on the ring gear. What that does is to add friction between the gears. If you are looking for efficiency and decent strength for a street car look at swapping an 8.8 there are real quick fox bodies using it. The pinion in the 8.8 is higher io the ring gear and reduces friction.

Just a little food for thought.

I believe someone on here swapped a rear end onto a 71-73 from an explorer. Seems like it was a direct fit, had good gears and was a trak-loc.

I'll take that 3.25 of of your hands if you ever get the gear you want.

I was going to start this post;

Yes a posi differential can be added to any 9............................

Click to expand...

Jeff,

Fer Friggin Shame!!!

A Posi, Cannot be fitted into any Ford rear, 9 or otherwise."

That is not fair to Jeff though.

Hehheh, this is one of the few Ford Forums, that doesn't draw hundreds of guy's pointing out that "Posi" or "Posi-trac" is a GM copyrighted name for their "Positraction" Limited Slip Differential(LSD). "Posi" is a commonly used, and just about universally understood to mean LSD. However as good Ford Mustang guys, we shoulden't use any GM copyrighted name for Ford products such as Traction-LOK, Trac-Loc et all.

Cmmon Guys, Lets not Posi, when we can LSD or Trac-loc.

OK Flame if you must.

Tubo

OUCH, I'm sorry! No flaming necessary... words DO mean something as does accuracy even though I don't care how the factory did it! LOL

Thanks for the correction Corky.