Horsepower is pretty cheap these days. Back when we were kids, 500-ponies on the street was something to really be impressed by; but by today’s standards, that’s the kinda output made by a “good street cruiser.” Heck, even new 392 Hemis are knocking out 485-ponies on pump gas all day long. With so many improvements made to easy-to-install, self-learning EFI systems; header-to-polished tip complete exhaust kits; and super low-friction, high-efficiency camshaft grinds, your turnkey RB440 can pump out 500-horsepower with hardly any effort at all. With that being as it is, it’s wise to beef up the rest of your drivetrain, and recently Mopar Connection got its hands on Proform’s Perfect Launch Dana 60 differential cover to do just that.
Above: The large capacity Perfect Launch Dana 60 differential cover is cast from heavy-duty aluminum and features thick webbing to a stout center cross-section that incorporates two bearing main cap support screws, as well as a pair of magnetic drain plugs (upper and lower). Extra fluid capacity and its aluminum construction also means better cooling, which is always welcomed.
Now, before you roll your eyes wondering what good a new differential cover can do, note that the Perfect Launch has a few tricks up its sleeve. The aluminum casting is unusually stout, with a thick mounting flange, webbing that buttresses the milled cross section (displaying the “Perfect Launch” logo) that also houses two Allen-headed bolts ending in large swivel pads (ie. feet).
These bolts are tightened down by locking nuts from the outside, while inside, the pads stabilize the Dana’s bearing main caps. When properly mounted and torqued per the supplied specs, the Perfect Launch cover will strengthen the differential housing case while under heavy torque applications. To that, the Perfect Launch cover also includes two magnetic drain plugs, new mounting hardware, and is cast deep to allow for added fluid capacity.
Above left: The cap support screws are backed off using an Allen-headed socket, but are held tight by a pair of locking nuts that are torqued down (more on that later). Above right: The swivel heads on the bearing cap load bolts are not meant to apply undue pressure on the bearing caps, but rather structural support.
Previously, our Currie Enterprises-built Dana 60 touted the same stamped-steel cover it came with from the factory decades ago. This cover provided little in the way of rigidity, but rather a plate to seal in the fluid. Yet, under heavy torque applications – which in the case of our Brazen Charger, are substantial considering our 4.56 gears spinning a pair of 35-spline axles bolted to a pair of Mickey Thompson ET Street S/S “cheater slicks”, all being stabilized by a set of Caltrac bars and Calvert mono-leaf springs – the housing will flex (albeit ever-so-slightly) under such duress.
The weakening of the housing may be incremental and totally unnoticeable to the naked eye at first, but continued stress can cause fracturing and eventual failure if not addressed. The thick aluminum casting and strength-adding ribbing are designed to transfer that torsional force from the input shaft outward to the tires as best as possible.
Above left: We first removed the stamped-steel Dana 60 cover. Structurally, the cover offered little to zero strength to the housing, nor included a drain plug, requiring us to carefully crack the cover free as not to spill oil everywhere. Above right: After letting the differential drain for a while, we cleaned the gasket surface, as well as inspect the bearing caps and ring gear for excessive wear or cracks.
As much as torsional force can fracture the casing; internally, destructive forces are at play here as well. During a hard launch from a dead stop, the strain placed on the pinion, ring gear and axles will look to find outlets to scrub this kinetic energy as quickly as possible. Unfortunately, this means exploiting weaknesses wherever they may be found, and more often than not, can be the hardware holding the differential together – the bearing main caps and bolts, in this instance.
The Perfect Launch’s set screws and pads are meant to help mitigate any potential failure by effectively tying the bearing caps into the differential cover, and thereby into the housing itself. Think of it as structural points in a steel building; the better the structure is tied together, the stronger the structure itself will be. The cap support screws are not meant to apply undue pressure (as caps aren’t designed to withstand pressure from the top of their arch), but merely support. Too much torque will place pressure on the cap and potentially oblong the bearing itself.
Above left: Per Proform’s instructions, we ditched the paper gasket and went with a trusty bottle of Right Stuff instant gasket maker. Sure, it’s a bit pricey, but it definitely does the job – and quick! Above right: We also applied a small amount of gasket maker (silicone is a suitable substitute as well) to the bearing cap load bolts’ threads as well as drain plugs prior to filling up the housing.
Moreover, additional bonuses provided by the Perfect Launch cover are both functional and utilitarian: the cover’s expanded bulge permits for greater oil capacity, and with added surface area and aluminum’s natural properties of dissipating heat, the Dana 60 will benefit from better temperature regulation. Excessive heat weakens components and seals, so this is truly an added bonus.
Additionally, the cover’s two drain plugs (an upper and lower) make for cleaner oil changes (no more having to pop the cover off to drain the differential fluid). It’s worth noting that neither the drain plugs or the cap support screws are gasketed or sealed, so some silicone or gasket maker is required to keep all four plugs from leaking.
Above left: The cover bolts should be torqued down to 25 ft/lbs. in a crisscross pattern. Above right: The bearing cap load bolts should be tightened snug against the bearing caps before being torqued to 10 ft/lbs. – that’s so you don’t injure the bearing or race itself. Finally, torque the locking (or jam) nuts to 10 ft/lbs. maximum as well.
That being said, we took an hour from our Saturday morning to show you how easy this installation is, and priced around $135 (per Summit or JEGS), this is going to be the easiest way you can add some serious rigidity and support to your Dana 60 with almost no effort at all.
Above: Because of the larger fluid capacity of the Perfect Launch differential cover, we crammed in just a little over two-and-a-half quarts of Lucas Oil High Performance Gear Oil into our Dana 60. The larger cover also made things a little too tight to conventionally pour fluid in, so we devised a makeshift pump that made filling it up a cinch. In all, the process required a little over an hour, a handful of tools and about $65 in fluids and sealant.