S197 8.8 Gear Swap - 2005 Mustang

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Swapping the Gears Continued and Gear Set-Up

121. Here is the bearing cup fully seated.		122. Using a mirror once again we will ensure the bearing cup is fully seated into the housing. There should be no gap between the bearing cup and housing.

123. The inner bearing cup installed.		124. Now we move to the pinion. Here there is a big advantage using the Ford Racing gear set. It is made for Ford using extremely tight tolerances. The Ford pinion will be marked with a number. Ours for instance is marked -6 (minus 6). This is our pinion bearing shim size.

Further explanation is required with regard to Photo 124 above. Ford uses .030 (thirty thousandths) as a base dimension. The -6 means that the correct pinion depth shim will be .030 minus .006 or .024 (twenty four thousandths). This can be a + or - number. A + 6 would mean .036 (thirty six thousandths) shim would be required. The old pinion was marked 0 (zero) meaning a .030 (thirty thousandths) pinion shim was required. Once installed this will give us the correct pinion depth into the housing. Pretty neat huh. This of course will be verified by our mesh pattern later.

125. These are pinion shims. Carrier shims are the same but a larger diameter. As you can see they are marked .010, .014, ect. This is the thickness of the shim. We need to make a .024 combination of shims. So we will use two shims one .010 and one .014 thickness.		126. Next, we place the shims on our new pinion gear shaft.

127. Apply anti-seize to the shaft where our new inner pinion bearing will go. This is the larger of the two bearings.		128. Now place the bearing on the shaft as shown trapping the shims under the bearing.

129. Now gently tap the bearing onto the shaft using a soft punch taking care to not damage the bearing cage. Seat the bearing fully against the shoulder and shims against the pinion gear.		130. Apply anti-seize to the pinion shaft and threads as shown.

131. Now install the pinion in place into the housing.		132. Once the pinion is installed into place, retain it in place by holding it to keep it from backing out.

133. Now insert the front bearing in place without the crush sleeve installed. It will be installed on final assembly.		134. Insert the oil slinger onto the shaft.

135. Here's the oil slinger and front bearing installed on shaft.		136. Next we install the pinion flange onto the pinion shaft. Hold the pinion from inside the housing to prevent the pinion from pushing out. We will not install the crush sleeve or the pinion seal until final assembly.

137. Place your Old pinion nut on the pinion shaft.		138. We will now tighten the pinion nut just snug enough to remove any forward and backward play in the pinion bearings. Then place our torque wrench back on the nut. We will tighten this nut incrementally until we achieve the running torque we measured on disassembly. Tighten the nut in 1/8th turns and re-measure the running torque; spinning the pinion thru at least one full revolution between checks. Remember to only tighten enough to achieve the running torque we measured during disassembly.

139. We now turn back to the carrier. We will place the carrier in the housing being careful that the pinion gear meshes with the ring gear and avoiding any hard contact between them. Be careful that the bearing cups do not fall off the cones while installing. This is where our bearing grease really helped us out.		140. Next we will install our bearing caps in place over the bearing cups.

141. Do not tighten them tight at this time. Only tighten enough to retain the cups in place. Be sure you place them on the proper side and direction we marked during disassembly.		142. Here is where we must use our depth gauge. Using a screw driver pry the carrier housing all the way against the pinion gear. Be careful as the bearing cups will want to fall off. Light but full contact is required.

143. Place your depth gauge so we will be able to measure the movement required to shift the carrier in the opposite direction moving the ring gear away from the pinion.		144. Take careful measurements to ensure the value. This will be the total thickness of shims that will be required for our carrier.

145. Now that we know the total thickness we will add .006 thousandths (for preload) and divide that by two. This will be the thickness of shims required on each side of our carrier. Use the shims required for each side and install them between the bearing cup and housing as shown. They will be tight and may require you to lightly tap them into place.		146. Now that we have our shims in place we need to torque our bearing caps to 77 ft lbs. Spin the ring gear several times while you torque to ensure the bearings seat properly.

147. Next we setup our depth gauge to measure the slop or backlash between our ring gear and pinion. Hold the pinion and rotate the ring gear measuring the total contact between the teeth. Do not let the pinion move. You can hear the click to hold the ring gear against the pinion, and then rotate in the opposite direct till contact is made again. We should only have 4 to 9 thousandths backlash. If you have less add shims in .002 (two thousandths) increments to the ring gear side of the carrier; subtracting it from the backside of the ring gear. This will move the ring gear away from the pinion. If you have more than allowed do the opposite and add to the backside of the ring gear subtracting the increments from the ring gear side. It may take you several tries to achieve this.		148. We have now reached the point where we check our work. The gear contact pattern test: First we clean off the ring gear of any grease or oil we may have gotten on it. Then we paint 4 or 5 teeth of the ring gear with our marking compound. Paint both the concave and convex sides of the teeth. Be sure you coat it well so when the pinion gear meshes with the ring gear there will be no questions as to where the contact is. Now we are ready to turn the differential thru a turn. We must do this thru both directions. While turning the pinion flange by hand thru a turn, be sure to put resistance on the carrier as if it were under a load. You only need to fight the carrier just enough to ensure the gears are meshing tightly. When you go thru one turn one direction; reverse the direction to mesh the gears as if in reverse.

149. Drive View		150. Coast View

Now we can see the mesh pattern on the ring gear. It should be in the center of the ring gear both -width-wise and length-wise. We refer to this as Center/Center. Compare your pattern to the chart below and make your needed adjustments to the shims as required. Don't get discouraged; this may take a few tries. Be sure to check the Drive (convex) and Coast (concave) sides of the teeth. The pictures above are an acceptable pattern.