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Traction-lok rebuild:
A brief traction-lok description: The t-lok, IMHO, is a very simple yet effective method of torque transmission. It uses a combination of frictions and steels; the steels spline to the O.D. of the side gears (the I.D. is splined to accept the axles), and the frictions keyed to the differential case (driven by the ring gear) with tangs. An S-spring is used to provide initial clamping load, then is supplemented by the outward forces created and transmitted by the pinion gears.

If you plan to rebuild the traction-lok, it is advisable that you do it now, for a couple of reasons: 1. Going to a numerically higher gear ratio, the pinion diameter goes down, and the ring gear thickness goes up. What does this really mean? The S-spring “gap” between the side gears is partially blocked (straight line of sight) by the thicker ring gear (you can still get the spring in, it’s just a bit tougher). 2. Without the ring gear, you can support the differential case by the flats (across the clutch cavity) on a block of wood, while driving the S-spring in place. Also, there are two approaches to component order: the factory method, and the alternating method. From the factory, t-lok’s are packed in this order: shim, friction, steel, steel, friction, steel, steel, friction, side gear. The alternating pack is as described: shim, friction, steel, friction, steel, friction, steel, friction, side gear. There is some debate on the durability of the alternating method, as you have reduced the number of splined components (thereby increasing shear and contact stresses), while increasing the ability to transmit torque. My contention? I’ve never seen a rearend go out due to t-lok spline failure; it’s usually axle related (OK, at some point the axles become stronger than the steel splines; at which point, I don’t know! Maybe somebody ought to “run some numbers”…). Both methods work: satisfy your particular needs and plan accordingly (I prefer and suggest the alternating method, FWIW.). The F5AZ-4947-BA kit will allow you to accomplish the “factory” set-up; for the alternating, you can buy a pack of frictions (see number below), or reuse two (one for each side) of your best existing frictions.

The rebuild: Soak the frictions in gear oil for a minimum of fifteen (15) minutes (while you clean the diff case, gears, and shims) prior to assembly in order to avoid dry working and possible component damage. Be forewarned: the clutches will still pop when first driven (I about had a conniption when I first rolled mine out of the garage after gears and t-lok! The thing popped about a dozen times in turns before settling out. I soaked mine about twenty (20) minutes, but the last set I worked on was soaked for about two hours. Result: only one or two mild pops, even with alternating frictions and a new F-150 S-spring!). With the differential case on one bearing, install the .045” thick shim in the bottom cavity. Apply a few drops of gear oil to the other .045” shim and place in the upper cavity (the oil will hold it in place, as long as the drops are towards the case…). Stack the frictions, steels, and side gear (engaging steels) in the lower cavity per your packing choice, then stack the upper units on the side gear, and install as a unit (make sure tangs locate in case). Install one of the pinion gears in place, and, while holding inward with one thumb, install the opposite side pinion gear 180 degrees apart (I prep the pinion gears first by putting a couple drops of gear oil between the gear and it’s steel bearing “shell”). Pick up the whole assembly, and install on the end of an upright axle. Rotate the diff case while holding the pinions inward as hard as possible; if you’re lucky, the “assembly” will roll right into place. If the shims are too thick, the pinion gears will not clear the case (acting like a built in gauge…). Change one shim to the next thinnest, and try again. If it fails to go together, change the other shim to the next thinnest: repeat until the gears rotate into position. It’s fine to have one shim .005” thicker than the other; just don’t end up with a .010” disparity. If the pinion gears line up, and the shaft will go through, you have it correct (It took me about three tries the first time, LOL!).

S-spring installation: This is actually the most trying part of the whole procedure! The S-spring, by design, has to be compressed to allow installation. The Ford (Helm) manual directs you to tap it into place with a rubber hammer; maybe one that weighed about 1000 pounds and was frozen rock hard! More people have had difficulty with this one seemingly simple task, and I’m no exception. I fought my first one for about an hour, then finally got it by compressing it in a vise, holding it compressed with a couple of pairs of needle-nose Vise-grips, and driving it into place. Shortly thereafter, Larry Turvy from the Corral offered a great tip: use two, 2” capacity worm-type hose clamps. Larry’s original suggestion was to use the clamps to compress the spring, but I still use the vise, then install the clamps, leaving a bit of the end exposed to get the thing started. Place the compressed spring into position, and start driving it into place with a hammer. With all luck, the spring will start in a few blows. Continue driving the spring in, until you stop on one of the “worm” portions of the clamp. Cut this clamp out with aviation or tin snips (Dremel or hacksaw may work), and continue driving, removing the other clamp when required. (Note: I found a 6-8” long piece of 1” x 1-1/2” rectangular tube, used as a “punch”, to be very helpful in “persuading” the S-spring into position, especially when using the F-150 unit!). Be careful not to drive the spring all the way through and out the back; sight down the pinhole and roughly center the spring. Set the unit aside for the time being.

Congratulations! You’ve just completed the Traction-lok rebuild (successfully, I hope)!
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