There are two limited-slip-style differentials available: the Equa Lok and the Traction-Lok. They are similar in design. The Equa Lok is quite rare because it was only used for a few years.
There are internal differences between the two and most parts are not interchangeable. The Equa Lok has four steel and three friction plates that are preloaded by a Belleville washer. The Traction-Lok has five steel and four friction plates. The first steel plate has friction material bonded to one side.
This Tech Tip is From the Full Book, FORD DIFFERENTIALS: HOW TO REBUILD THE 8.8 AND 9 INCH. For a comprehensive guide on this entire subject you can visit this link:
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The assembly steps are very similar, except that you need to add a limited-slip clutch pack if you have a Traction-Lok differential. The clutch pack consists of clutch friction plates, steel reaction plates, and shims. This is very similar to the 8.8-inch assembly process, just with more pinion gears and a different preload spring arrangement.
Step-1: Apply Grease to Pinions
Apply assembly grease to the back of the pinions, to the side gears, and to the washers to help keep them in place.
Step-2: Install Side Gear in Differential Case
Install the same spline tool in the vise as shown in step 6 on page 72 for an open differential. Put the differential case in place and load in the first side gear with its washer in place. This is the side gear with the shoulder on the back surface.
Step-3: Partially Assemble Differential
This part of the assembly follows the procedure for the open differential (see steps 8 and 9 on pages 73 and 74). Make sure that you have all the pinion washers in place.
Step-4: Install Differential Support Block
Install the differential pin support block, which has four small holes in the corners. This block is symmetrical and does not require any special orientation.
Step-5: Install Roll Pins
Install and fully seat the three roll pins (see steps 14 through 17 on pages 76 and 77). Take extra care to not dent or ding the pilot diameter surfaces. Note that this pilot diameter is countersunk, as opposed to being a raised surface as with the open differential.
Step-6: Install Preload Springs
Here you can see that all of the pinion washers are in place. The three roll pins have been tapped in just below the mounting surface. Now you need to install the preload springs for the clutch pack in the bores of the differential pin block. Dip each one in assembly lube before you drop it in place (left). Repeat until you have all four springs in place (right).
Step-7: Grease Pinions
Add another dab of the grease on the visible end of each spring. Add some grease to all four pinions, rotate to feel for smooth motion, and perform a final check to be sure that all springs and washers are in place.
Step-8: Install Spring Plate
Add the spring plate. Orient it so that the arched cutouts line up with the long differential pin. The long pin is the one that has only a single roll pin on the axis (the one in the middle of the three pins).
Step-9: Apply Grease
Fully seat the spring support plate. Add a thin layer of assembly grease on the back of this plate with an acid brush.
Step-10: Install Differential Pins
Install and align the three differential pins, which is just a matter of pushing them in place by hand (see step 12 on page 75). Don’t forget to double-check the alignment of the roll-pin holes.
Clutch Pack Sub-Assembly Step by Step
Step-1: Inspect Clutch Pack Components
The clutch pack components are laid out in order of assembly along with the steel wear plates. I recommend pre-soaking the clutch plates in friction modifier for at least 30 minutes prior to assembly.
Step-2: Pre-Lube Clutch Carrier
The next step in working on the clutch pack sub-assembly is to pre-lube the clutch inner plate carrier. You can use common gear oil for this.
Step-3: Install Reaction Plates
The tabbed outer reaction plate has friction material on a single side (left). Most people refer to this as the composite plate. The four tabs fit into the mating slots in the differential case. Install the first reaction plate with the friction surface down, which is in contact with the inner plate carrier (right).
Step-4: Install Friction Plates
The friction plates have friction material on both sides, so there is no concern as to which side is installed up. These plates have the mating teeth in their inside diameter and line up with the teeth on the inner plate carrier.
Step-5: Install Steel Reaction Plates
The reaction plates are plain steel. Continue to build up the clutch pack alternating between steel reaction plates and friction plates. There are four steel plates, four friction plates, and one unique composite plate, which has friction material on only one side.
Step-6: Finish Clutch Pack Buildup
When you have the entire clutch and reaction plate pack correctly assembled, the sub-assembly should look just like this. The top plate is a steel tabbedstyle reaction plate.
Step-7: Install Four Reaction Plate Wear Caps
These stop the tabbed plates from wearing into the softer cast iron of the original Ford castings that are soft compared to aftermarket units. The five missing teeth on the inner clutch plate carrier are oil transfer holes. This feature allows oil into the clutch pack to help lubricate the pack. More importantly, it transfers heat from the plates to the incoming fresh oil.
Step-8: Apply Grease to Clutch Plate Carrier
Step-9: Install Inner Plate Carrier Washer
Differential Cover Assembly Step by Step
Step-1: Install Outer Carrier Plate
Step-2: Install Shim
Step-3: Install Clutch Pack and Inner Plate Carrier
Step-4: Oil Clutch Pack and Inner Plate Carrier
Step-5: Set Side Gear into Position
Case Halves Assembly Step by Step
Step-1: Gather all Components
Step-2: Bolt Differential Halves Together
Step-3: Press Case Halves Together
Step-4: Check Preload
Step-5: Align Side Gear and Inner Plate Carrier
Step-6: Index Teeth for Alignment
Written by Joe Palazzolo and Republished with Permission of CarTech Inc