Differential covers serve an important role that not many people think about. Many are neglected and forgot about when having their truck serviced, but we’re going to go over why you shouldn’t overlook a performance differential cover. Also, thanks to our friends at BD Diesel Performance, we are going to be installing one on our project truck, DeadSpool.
So, for starters, the factory differential cover’s are meant to contain fluid in the differential, hold only the necessary amount of fluid to function and look good enough to sell at the dealer. The ring gear and the pinion gear turn thousands of times and eventually they will fail. But, by adding a performance cover, you can lengthen the life of your driveline parts by a marginal amount.
For instance, this BD Diesel cover for the AAM 11.25 differential, is a cast aluminum structure with internal and external cooling fins and features a large drain and fill port. For those of you who do service differentials, on a Dodge, you know how convenient this is when it comes to draining. Pulling the bolts off of the cover to drain can get messy fast.
While there will be wear and tear over time, these covers feature magnetic drain plugs to catch any debris from continuously floating around the case. Additionally, unlike the factory unit, this comes with stainless steel allen head cap bolts, plugs, and an integral reusable Viton o-ring around the surface to keep the cover mated with the differential securely preventing leakage.
The inside design of the cover keeps the oil on the gears longer and deflects oil back onto the ring gear and into the pinion gear for a cooler longer life. The additional surface area on the covers allows for more fluid to contact the gears which allow the gears to stay lubricated for longevity.
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These covers mean more than just make the underside of your truck look better. There are many factors in mind when covers are designed including better fuel mileage, minimal frictional loss, heat dissipation, and maintaining usable horsepower and torque.
Keeping differential temperature at a minimum is actually an important factor. So, by using an aftermarket differential cover that is designed to fluctuate fluid more efficiently, you’re lowering the overall operating temperature in the differential resulting in less friction. For instance, a diesel truck can make 350 horsepower at the crankshaft, but actual numbers being applied to the ground aren’t the same, due to parasitic loss. With a better flowing cover, you’re actually lowering that loss. While it may not be a huge amount, you’re still gaining.
For instance, the factory axle in our project truck is an AAM 11.5 differential. The manufacturer’s owner’s manual suggests you fill these axles up to the fill mark which is parallel with the fill hole. While the truck is in motion, the fluid will sling and spread throughout lowering the actual level of fluid. If overfilled, you will encounter what they call a viscous loss. A viscous loss is when heat is applied to the lubricant in the axle which will in turn lower miles per gallon and horsepower.
We are excited to see how much longer the fluid will last in our new cover now. For more information on what BD Diesel Performance offers, be sure and check out their website. Stay tuned to Diesel Army for more tech pieces and the latest in diesel.