Maintenance is something that we all need to keep up with in order to keep our trucks running the best they can. While oil changes seem to be talked about most often, other fluids also need to be looked into from time to time. Take for instance the differentials, transmission, and transfer case. Jim Marrone recently purchased a 2021 Ram 2500 with 40,000 miles on the clock, and since he didn’t know anything about its former life, he figured changing the fluids in these usually overlooked areas couldn’t hurt.
So, to accomplish this, he decided that instead of going to the local department store and buying whatever was on the shelf, ordering several quarts of AMSOIL Severe Gear and ATF fluid, as well as a Banks Power rear differential cover should get the job done. The AMSOIL fluid is a no brainer, as the synthetic fluid is some of the best in the industry and the new easy-to-use Easy Packs make filling the differentials and transfer cases easier than ever.
The Banks differential cover cools the fluid in the housing better because its air scoops (left) capture air and redirects it up through its long, thin fins. The fins extend into the cover so the heat from the oil is transferred to the fins, through the cover, and out to the atmosphere.
Why Upgrade The Differential Cover
When thinking about an upgrade for your truck, what do you look for? Are you a performance junkie or do you want a rig that can haul and tow things better? Some truck owners would like both, and that’s one of the reasons manufacturers like Banks Power create the parts they do.
While the benefits of some upgraded parts might be easily noticeable, some offer a true benefit that not many understand. Take for instance your truck’s rear differential cover. From the factory, it is designed to merely keep the fluid in place. But that simple objective can be improved upon, and that is why Gale Banks digs deeper.
Designing A Differential Cover That Does More
While you see a simple cover, Banks Power sees an opportunity for improvement. But before any product can get the Banks name on it, it has to be better than anything on the market. “We tested several high-capacity flat-back-style covers [from other companies]”, says Jay Tilles, brand manager at Banks Power. “The selling point on those other covers is they hold more fluid, therefore they cool better. But we found this to be misleading. While the fluid does take a little longer to heat up than with a stock cover, it also takes much longer for the fluid to cool. Simply adding more fluid is not the answer. Better heat rejection is! Those high-capacity covers have no real cooling fins. What they do have are less than ¼-inch tall and are just decorative.”
High-capacity, “flat” differential covers can aerate the oil. As the differential spins, it slams the oil into the flat surface of some covers, forcing air into the oil. Air is not a good lubricant. The Banks cover follows the stock inner curvature, forcing the oil to follow a smooth path and lubricate all moving parts of the differential.
The crew at Banks felt they could design a rear differential cover that would cool the fluid exponentially better than anything on the market, and what they developed looks nothing like anything else you can buy.
For starters, all aftermarket differential covers have cooling fins. Unfortunately, the cooling fins on most covers are useless as the area directly behind the differential does not see any airflow while you are driving. Think about it, what is there to make the air flowing under the rearend to turn 90 degrees and make contact with the cooling fins on the cover? Also, the cooling fins of most aftermarket differential covers are 1/4-inch tall and very thick. That design does not help much with cooling.
The Banks differential cover easily installs in place of your OE cover. However, this Ram has a rear sway bar, so spacers were ordered with the cover to push the bar rearward to allow clearance for the cover. If your Ram has a rear sway bar, you will need to order the shims.
A Cover With Forced Cooling
When Banks designed his cover, the first thing the team realized was they needed to find a way to get the air to turn 90 degrees and make contact with the cooling fins on the differential cover. To do that, the Ram-Air scoops were developed.
The Ram Air scoops direct airflow upward, toward the fins so the moving air can absorb the heat from the fins and carry it away from the cover. According to Banks Power, this design cools five times better than any flat-back cover because of others’ lack of airflow over the “fins”.
“Another reason that other high-capacity covers and stock covers don’t do a good job of cooling is that there’s virtually no air flow behind the rear differential”, Jay said. “Using anemometers, we measured air velocity in front and behind the axle. At 55 mph on the highway, we saw less than 11 mph air velocity from the face of the diff cover stretching to the rear bumper. In other words, the axle splits the air like a wedge. There’s a dead air zone behind the axle. That’s where our Ram-Air scoops come in. They redirect air up through the fins.”
The Banks cover hangs no lower than the OE differential cover. However, if you do find yourself off-road and getting hung up on an obstacle that does grab the scoops on the cover, they are designed to break away so the cover is not ripped from the differential. But as they say on late-night television, but wait, there’s more…
Whoever came up with these plastic bags is a genius. Bottles never fit in tight places and these make filling a differential and transfer case easy.
Other aftermarket differential covers have another inherent flaw: they are flat. This causes severe issues with oil aeration and oil control within the differential. It comes down to fluid dynamics. Think of it like spraying a hose against a wall. With a flat-back differential cover, the oil splashes against the cover and is not directed to where it is needed (the bearings and gears). It simply splashes all over. This splashing causes the oil to aerate, and when oil is aerated, it cannot properly lubricate.
Internal Improvements
If you look at the inside of the Banks differential cover, the first thing you notice is it has internal fins and is curved like the factory differential cover. These fins, grooves, and curvature direct oil to where it needs to go to keep your truck’s rearend properly lubricated with better-cooled oil.
With the differentials and the transfer case fluids changed. the truck can travel plenty of miles before it needs another fluid change underneath.
Although we are not getting that technical with this install, all Banks differential covers also include a sensor port for differential-temperature monitoring. What most truck owners will appreciate are the easy-access fill port, a magnetic drain plug to simplify oil changes, and sight glass for easy viewing.
While many upgrades are designed purely for performance reasons, adding the Banks differential cover and changing out the fluids with AMSOIL might not add up to any horsepower numbers, but Jim can be sure that the durability and reliability of his Ram has been extended longer and that he will be on the road without worrying, for years to come.
