[ryans88gt]

OK, so I rebuilt my Trac-lok yesterday and I thought I'd take some pics to help out those of you that need to do the same or think it is too hard.

So...here goes.

General: Buy a box of latex gloves and get a couple rolls of paper towels. You don't want gear oil on your hands because the smell sticks around and it is impossible to get off decent shop rags.

Step 1: Jack the car up and support on jack stands on the subframes, letting the axle hang down. Place the car in neutral with the e-brake off.

Loosen all ten bolts holding the diff cover on the center section.

Put a oil catch pan under the center section.
Use a small screwdriver and hammer to pry the cover off the center section, letting the oil drain out.

Once you get the cover off you should see something like this

[ryans88gt]

Step 2: Loosen lug nuts and remove your wheels. If you have drum brakes pull the drums off if you can. If not, loosen the brake adjusters and them pull them off. If you have rear disks, take the calipers and caliper bracket followed by the disks off.


Scrape all the gasket material or RTV off the mating suface of the center section.

Take the fill plug out of the front driver's side of the center section. This one may be magnetic and if so clean all the metal off of it.

Take some paper towels and wipe down the inside of the center section and spray clean with some brake cleaner. This isn't absolutely necessary, but it makes the rest of the job a lot nicer.

[ryans88gt]

Step 3: Now you are ready to work.

Rotate the ring gear around by hand until you locate the 5/16" bolt that holds the planetary pin and remove this bolt.

Once you have the bolt facing you, put the car in gear and remove the bolt.

Put the car back in neutral.

You can now push the pin out part way, rotate the ring gear around and pull the pin out of the differential

If you feel slight resistance when taking the pin out this is OK, but you shouldn't have to more than lightly tap it with a thick punch. If you do encounter resistance check to make sure it isn't hitting something or binding somewhere. Usually it just slides right out.

[ryans88gt]

Step 4: With the center pin out and your drums or disks removed the axles should be free to slide towards the center section. Push them in one at a time to expose the C-clips. You can see the C-clip on the passenger axle in the pic. Remove these by gently taping the open end with a long screw driver, they are only held in place by friction with an o-ring on the axle.

[ryans88gt]

Step 5: Once you have both C-clips off you can pull the axles out of the center section. No reason to pull them all the way out of the housing unless you want to inspect them. If you are not planning inspection, you only risk tearing the seals by pulling them out so it is best to just leave them 3/4 of the way in the axle housing. Here in the pic you can see the axle ends with C- clips removed. You can see the o-rings that hold the C-clips in place. The c-clips will fall to the bottom of the housing. I alway loose at least one in the gear oil pan under the center section, so have a magnet ready.

[ryans88gt]

Step 6: After you slide the axles out you can drive the S-spring out. I use the wooden side of a hammer and give it a few hard hits. If it seems like it is hung up, rotate the ring gear around to see the other side. With 3.55 gears or bigger it will hang up on the ring gear and you will need a screw driver to wedge the end loose.

Pics show diff before and after the spring is driven out.

[ryans88gt]

Step 7: Slide one axle back into the differential gear after the S-spring has been removed. See above pic.

Put the car in gear and the turn the reinserted axle by hand

[ryans88gt]

As you turn the axle, the planetary gears will spin out of the differential and fall out. Be careful not to loose the race on the back of each gear.

One those gears have been removed you can start removing the differential side gears and clutch packs.

[ryans88gt]

Step 8: To remove the side gears, here is a trick. Start with the passenger side. Pull the axle halfway out and then push it back in without trying to line the splines up. This will push the gear into the differential so you can pull it out easily. Sometimes they don't want to come out since they are stuck with gear oil.

After you remove the passenger side, you can remove the drivers side. Try to keep the clutch packs with the gears and note that there should be shims in there as well.

Now is a good time to check your gear mesh with gear marking compound and check your backlash with a dial indicator. Backlash is the freeplay in the gears and should be between 0.008" and 0.015". Mine was at 0.012-0.013" so it was within spec. If yours is higher you need to take shims from the passenger side of the carrier bearings and move them over to the drivers side. PITA, but it should be done. Also you can check runout of the ringgear. It should be no more than 0.004". If it is more you will hear vibrations and wining. To correct, you have to take the ring gear off the carrier and lap on 300 grit sand paper to remove high spots and then reinstall and check again. This stuff is not absolutely necessary, but while you have it apart, you might as well check it.

[ryans88gt]

Step 9: After you have checked you gears out and are satisfied that you do not need to replace anything else while you are in there it is time to repack the side gears.

1) Take a micrometer and measure the thickness of the clutch pack and shim on each side. Mine was 0.650" on one side and 0.645" on the other.

2) Note that the clutches are packed:
Side Gear-Clutch-Steel-Steel-Clutch-Steel-Steel-Clutch-Shim-Carrier.

This is the stock configuration.

3) Take the old clutch pack and throw it away...wait not all of it, save the one clutch that was against the shim (one side is still good since the clutch doesn't rotate relative to the carrier).

4) I assume you have already bought a rebuild kit. Laurel Mountain Mustang sell them for less than $50 and they come with friction modifier and shims and a new 5/16" pin bolt....along with the steels and clutches.
Another option is the carbon fiber clutch kit that is made for the 03 cobras.

Here is another point I would like to add. You can convert your trac-lok to 31 spline by purchasing 31-spline side gears.

5)When you repack, the performance way to do this is:
Side gear-clutch-steel-clutch-steel-clutch-steel-flipped reused clutch-shim
this gives you an extra clutch on each side at the expense of a steel.

6)Important points when repacking:
soak clutches and steels in gear oil for an hour before repacking
Put the stack together and measure it with a micrometer...remember used mine measured 0.650 and 0.645". Add shims to get you back to the same width, I like to add 0.010" to make sure it is good and tight. So my clutch packs measured 0.660" when I put it back together with a 0.025" shim.

You can see the width stamped on the shim.

[ryans88gt]

Step 10: Now you put the shims, clutch pack and side gears all back in as one piece. Line up all the ears on the clutches and it should slide right in. May take a little fiddling to get everything in place. The driver's side has to go in first then the passenger side.

Note in the picture, there are 4 clutches. THe one on the outside, the ear is a little different color. That is the old reused flipped clutch.

[ryans88gt]

The next two steps people like to make really hard, but I am going to tell you the easy way to do this.

Step 11: getting the planetary gears back in....
Put the car in gear if it isn't already and slide one axle into the side gear without dislodging it...i.e. carefully.

Put one planetary gear anywhere on the side gears and slide the side the pin through it. Hold this with on hand and slide the other planetary gear on the side pin. Now the pin is locating them 180 degrees apart like in the picture.

Now you gently rotate the axle until the planetary gears start to engage the carrier (make sure the races are on the gears and they are not binding on anything). Stop once the pin hits the carrier and slide the pin out. The gears will be held in place by the carrier at this point. See pic 2.

[ryans88gt]

Rotate the axle some more until the planetary gears seat in their original location. To line them up perfectly, put the car in neutral and spind the ring gear slightly so you can place the pin into the carrier and gears to make sure everything is lined up.

[ryans88gt]

Step 12: What some people argue is the hardest part of rebuilding a trac-lok. Replacing the S-spring.

The S-spring (see pic) is a harmless looking little S-shaped spring. But getting it back into place has made even the coolest heads go .

So how do you get it back into place without loosing your cool?

Worm gear clamps.

2 of them. Tighted down the S-spring using a 5/16" ratch on quality worm gear clamps to compress the spring. See pics

[ryans88gt]

Flatten the ends of the worm gear clamps by gentle tapping with a hammer.

You should be able the compress the S-spring enough with the clamps to slide it in with just a littler persuasion with a hammer. Center the S-spring as much as possible

Then you loosen the clamps, get a pair of vise grips and a small screwdriver.

Grap the clamp with the vise grips and wedge the screwdriver between the side gear and the spring, to take the tension off the clamp. Pull the clamp out with the vise grips.

[ryans88gt]

It's all down hill now. Push the axles back in and put the C-clips on. Pull the axles out to seat the C-clips.

Hopefully at this point the holes in the planetary gears are still aligned with the holes in the carrier. If not, put the car in gear again and use a long breaker bar to turn one of the axles which will rotate the planetary gears. Do this little bits at a time to line up the gears and the holes so the pin can go back into place.

The pin may be a little tough to put back into place as the axles are now 0.010-0.020" closer to the pin than before (due to the rebuild thickness). However, you should in no way have to hit the pin harder than a light tap. If you do, something is wrong or your shims are too thick.

Don't forget to tighten down the pin bolt with threadlocker...it'd be a mess if this bolt came loose!

[ryans88gt]

Once everything is together, spin the ring gear around to make sure it isn't binding. Put the car in gear and see if you can spin one wheel with a bar between the studs.

Usually you can spin one wheel easily before the rebuild and not at all after the rebuild.

Black RTV is all you need to put the diff cover back on. In this case I am putting a diff girdle on there, but it hasn't arrived yet. Pics when it gets here.

Fill with gear oil and the whole bottle of friction modifier. If you didn't get the kit with the friction modifier, you can buy some at autozone for $4.

Once oil starts to come out the full plug, put the plug back in with some RTV on it. Let the RTV cure overnight and check the bolt tightness again. This will keep things from leaking for the long haul.

Take the car for a test drive and take some corners under power and listen for any unusual noises. Enjoy the wonders of a two wheel burnout.

[ryans88gt]

The end of the How to.

[Iwannagofast]

this is awesome ryan.........i vote STICKY for sure

[HMUSN]

nice write up man