I am waiting on a used 31 spline track-lock (ford posi) to arrive and I wanted to know what to look for besides the obvious worn splines etc. Can I perform any checks to determine whether a rebuild is in order? How difficult would it be to rebuild and put in new clutches? I have a good assortment of hand tools to include a torque wrench, but thats about it. I know it will take special skill to properly set up the gears but I want to see how much of this I can do on my own.

Look for obvious wear on the gears, check the backlash with a dial indicator on the ring gear. It would be about .008" to .0013" for brand new gears and will be considerably higher for stuff that is used.

BGH can tell you what's acceptable, but you can bring the backlash back in very easily on a 9" chuck.

You can test the Trac-Lock by sliding the axles in and checking the break torque by turning the axles against each other. You should have to apply a considerable amount of force to get the axles to turn aganist each other.

As long as the gears and bearings are OK, rebuilding the posi is pretty easy with hand tools. Kits are readily available. (there are two and 4 pinion 9" diffs. check which you have!) Just make sure to reset the backlash and check for a good gear pattern when you're done.

Paul,
Thanks for the response! I already have a good used set of gears, I only purchased the track lock carrier. I know the gears will have to be set up for a fact. As insurance I was already planning to replace the bearings. My 9" is/was a 28 spline open unit and I'm upgrading to 31 spline posi. I haven't had the housing narrowed yet and also don't have the new axles.

Any other advice would be appreciated, I'm all ears LOL!

Also, if anyone can suggest a good book or video as well?

I'm working on the book, but it won't be done for a long time. I am making pictures and collecting information.

The 9" Traction Lock has a split case. The side of the case with the ring gear flange tends to crack and break with hard use. When this happens it usually takes out everything in the rear end. There are 2 different designs of this case half. The weaker design has holes cut all the way through for the clutch ears. The stronger one only has counterbores on the inside of the case. US Gear makes a steel case half that is stronger than any of the Ford cases. I have not seen a used Traction Lock yet that had good clutches in it. They almost always need new clutches. The Traction Lock is a little more difficult to set up the clutches than the Eaton posi because the case has to be split each time you change the shim thickness for the clutches. The Traction Lock is also bad about welding the pinion gears to the cross shafts. If this happens then you might as well chuck it and find another one. There are other things to look for, but I could almost write a chapter on this subject alone. I do rebuild these for customers if you don't want to mess with it.

Thanks BGH and Paul both. I will check it out as soon as I can and probably be back in touch!

One othere tip/note... I use to haev problems with a trac-lok not launching locked up (i.e. spin one tire with slicks on!)... ended up changing from Mobil 1 synthetic gear oil to plain old 80W90 conventional oil, and not using the anti-chatter additive, it launched fine. More than likely the synthetic was just too slick for it. Thought I'd pass it along in case you have any issues. -Dan