Beyond Vehicle Maintenance: Installing a Differential Cover
I finally started putting together my ‘69 Chevelle, which included installing the differential cover. The procedure for this vehicle repair is similar for many cars and trucks. So let’s get started!
My differential is a Chevrolet 12 Bolt posi-traction that I recently stripped out to get powder coated. As you can see by the pictures below, I have the differential out of the car.
If you are working with an installed differential, go right to the cleaning phase. I would suggest covering/plugging the carrier and oil passages to keep dirt from entering the bearings, gears, and/or clutch plates while you are cleaning.
Before installing the carrier and axles, I chased all of the threads in the housing with a tap to make sure they were clean of powder coat. Paint buildup can also cause issues, so you should make sure all threads are clean and dry at the start when assembling and torquing bolts.
Phase One: Cleaning
In the picture above you will notice the Loctite® Pro Strength Parts Cleaner. Any cleaner that dries residue-free will suffice. I applied the cleaner to a clean rag or paper towel and wiped the flanges several times, moving to a clean spot on the towel each time until I stopped seeing dirt/scum buildup. As with any sealing application, clean and dry makes for a good seal. My housing and cover have both been powder coated. If this were paint, I would clean to the metal with the solvent.
Phase Two: Sealing
I chose Loctite® 598™ Black Silicone as the sealant because it has excellent oil cutting and resistance properties and will give me a consistent clean look after assembly. I eliminated the original cut gasket because over time they dry out, shrink, or crack. I cut the nozzle back somewhat to allow for an opening of about 3/16”. This allowed me to apply a larger bead size with a little more speed. I applied the sealant to the differential cover on the areas where the cover came into contact with the housing flange. Make sure to go around each of the bolt holes as shown below.
Phase Three: Bonding
Next, I applied Loctite® 243™ Removable Threadlocker to the bolts that secure the cover. This not only provides lubrication, a consistent torque, and ensures the bolts will not come loose, but it also can be disassembled when I want to change my gear ratios. The housing on my 12 bolt has both through holes and blind holes (bottom out). For the through holes, I applied a drop of 243™ to the bolt. On the blind holes, I applied a drop of 243™ on both the bolt and the hole. The 243™ nozzle will fit inside of the 5/16” threaded hole. If you don’t put the threadlocker in the hole and you only put it on the bolt for a blind hole application, the air pressure created when you tighten the bolt can push the threadlocker out from between the threads.
I tightened the bolts in a cross pattern all to snug at first, then to the 20 ft•lb torque spec required for my application. (Check the spec for your specific application.)
It is normal to get a little squeeze-out, which can easily be wiped off when wet or trimmed with a blade after it cures. The pictures below are before and after wiping clean.
And that’s it! I hope you found this helpful, and good luck on your own vehicle repair projects.
If you found this interesting and would like to read more of my blog posts, check out How to Remove an Air Pump, Using Loctite® Freeze and Release in Auto Maintenance, or Exhaust Leak Problems and Repairs.