Trac-Lok Install questions

Phillio99

Registered User
I've been looking around for some info on installing a trac-lok differential into a carrier with an open diff. Does anyone have a write up or any first hand experience? Will I need any specialty tools, is there a certain rebuild kit I should be after, and is it significantly easier with the carrier out of the car? As always, responses appreciated.
Thanks,
Phil
 
The parts swap itself it pretty straight forward. Once the parts are in is when the fun begins. You need to set up an indicator on the tooth of the fing gear. Hold the pinion and read the back lash. With used gears backlash can be high. The pattern is the most important thing. Once you have your backlash at or above spec start checking the pattern. Using shims bring the pattern to where it was before or where it needs to be. Do not allow backlash below
.008 at the most. A terrible howl will result. Another tip is about tightening the crush sleeve. After you tighten it and it checks out at 16-20 ft-lbs for preload, smack the flange with a hammer. Don't beat the heck out of it but go around 4 sides hitting it every way to make sure everything is seated nicely. Then check it again. If it is not at the required preload now, tighten the nut a little more and repeat the process until no change occurs.
Alan
 
Depending on what gear you want to run, you could always pick up a trac loc from an 89-93 auto which would have 3.27 gears. Not sure what gears came in 5-speeds, anyway you would have to unbolt your whole differential, 4 bolts, unbolt the driveshaft and pop out the axles and install it, no having to set up the clearances on the gears.
 
Pinion preload is in Lb-In NOT Lb-Ft.

From the shop manual:

Adjustment Torque Specifications

Description Rotational Torque Nm Lb-In

Pinion Bearing Preload — 0.9-1.6 8-14
(Collapsible Spacer) Original Bearings

Pinion Bearing Preload — 1.8-3.2 16-28
(Collapsible Spacer) New Bearings
 
Thanks for the input guys, a backlash indicator isn't something the local parts store is going to have in their loan a tool program is it? I'm assuming this is a far easier process out of the car. It would be in my Mark VIII and it would be used 3.73's, the trac-loc is suppose to be rebuilt but I may give that a whirl too. Any additional tools for that rebuild, pointers or good writeups? Keep the pointers coming guys.
Thanks,
Phil
 
Pinion preload is in Lb-In NOT Lb-Ft.

From the shop manual:

Adjustment Torque Specifications

Description Rotational Torque Nm Lb-In

Pinion Bearing Preload — 0.9-1.6 8-14
(Collapsible Spacer) Original Bearings

Pinion Bearing Preload — 1.8-3.2 16-28
(Collapsible Spacer) New Bearings

you are correct I'm glad you caught that. Sorry about the typo
I use 16-20 in-lb on them per the rebuild kit instructions and have never had a problem.
Alan
 
At the least, you need a case spreader (I made one), a dial indicator, and a couple of torque wrenches.

Additionally, you may need to replace the pinion bearings and cones and the side bearings and seals which require special drivers to do correctly.

Most of all you need experience, it's not something I'd recommend for a beginner.
 
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I completely agree. Differentials are not at all easy assembly. Even for an experienced builder 8.8's require patience and a perfection attitude. Pattern is by far more important than backlash especially when dealing with used or aftermarket gears. In general if you get the correct pinion shim on brand new FORD gears when the backlash is right the pattern will be as well. Motive gears are very nice in fact on a performance level I would call them the best I have used. On an installation level I would call them the worst.
Alan
 
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