9" Traction Lock Shim

[cjjhalfcab]

Rebuilding my first 9" traction lock (bought used), and once I cracked it open, the clutches looked really good - but no shim. Apparently I'm not the first one in this one. Every build video I've seen, and every post I've read on it says Ford shimmed these. Would it be possible that it wouldn't need a shim at all? I don't have the right stuff to check the preload, I'm guessing it takes a special tool I don't have, and I don't have a spare 31 spline axle and chop saw to fab one, so I'm at shade tree level on this. Read where one guy said to assemble it without the 4 tension springs, and spin the carrier on a (fixed) axle. If there is drag you're good, if it's hard to turn it's too tight and will chatter on corners. Sound about right? I tried this with new clutches, and it drags pretty good.
Other than that, I'm not sure how I'm going to check the preload on the clutches, and I can't go back to the original shim(s), even if it would be right with them.

 

[Broncobowsher]

I'll start off with I don't have the highest opinion of the factory limited slip.
You mention 31 spline axle. I take it you are doing a 31 spline upgrade and thus the reason for swapping?
Unless you really need factory levels of limited slip, the spec is to match factory specs. I would just put in what you have and call it a day.
Usually people add extra frictions to try and make the limited slip more limited and less slip. While the factory tends to minimize frictions so there is just enough but not too much to get into drivability.

 

[cjjhalfcab]

This is in a later (mid-80s) truck with an 8.8 - I want to swap to a 9", and the donor I have is a 31 spline L/S. This won't see hard offroad use, more along the lines of what I'd consider "farm-type use".

 

[Quick & Dirty]

Read where one guy said to assemble it without the 4 tension springs, and spin the carrier on a (fixed) axle. If there is drag you're good, if it's hard to turn it's too tight and will chatter on corners.

Factory spec for new clutches is 100 to 250 ft-lb resistance while slipping. Initial breakaway may exceed 250 ft-lb. For used clutches, 40 ft-lb is the minimum acceptable.

 

[cjjhalfcab]

Factory spec for new clutches is 100 to 250 ft-lb resistance while slipping. Initial breakaway may exceed 250 ft-lb. For used clutches, 40 ft-lb is the minimum acceptable.

I've read that, but never seen anyone explain or make a video showing just how you check that.

 

[Oldtimer]

 

[cjjhalfcab]

View attachment 927228

Interesting - thank you!

I found this old article, but not too crazy about leaving the preload springs out. Seems like intelligent engineers thought they should be there.

https://www.motortrend.com/features/traction-lok-differential-july-1989-982-1436-48-1/