Muscle Mustangs & Fast FordsProject Vehicles
Project Smog-Legal Killer - Power to the Pavement
Turning our smog-legal horsepower into forward motion.
As many of you already know, the Traction-Lok is a clutch-pack-style limited-slip differential that uses clutch discs and plates to apply traction to both wheels. This not only makes for a versatile differential, but it also means the unit is easily serviced when the old discs are worn out. Which brings us to our decision to use a new FRPP unit from LRS.
Even after nearly 300,000 miles of service and numerous rebuilds on our old Traction-Lok, if our motor made less power we could have likely rebuilt it and called it a day. But with so many miles under its belt, we thought it wise to start with a completely new unit since 500 hp can quickly wreak havoc on worn drivetrain components. We consider it cheap insurance, not to mention the new one also comes with the upgraded Kevlar clutches. Ours came spec'd for 31-spline axles, another wise upgrade for serious power planting.
As anyone who's installed rear end components can tell you, it's not the big parts that kill you, but rather all the seals, oil, shims, and small bits. But thankfully LRS has taken the guesswork out of the equation with its rearend installation kit, which comes with everything needed to get rolling, save for wheel bearings and axle seals.
Like our worn Traction-Lok, the coupe already had FRPP 3.73 gears, but with more than 150,000 hard miles on the gears, we thought a new set was definitely in order. The LRS kit came with the FRPP ring and pinion gears, a master bearing and shim kit, FRPP friction modifier, Royal Purple 75W-90 gear oil, all gaskets, seals, and even marking compound. Seriously, the kit came with everything needed for a carefree install. Forget rushing to the local auto-parts store for a gasket or seal—the LRS kit saves the hassles.
With a new differential and gears in place, it was time to select quality axles. We upgraded to Moser 31-spline, Fox-body-length, five-lug axles from LRS. These burly units up the spline count from the stock 28 to 31 for more strength. Speaking of strength, the Mosers are made from hardened steel for the utmost durability.
Before wrapping up the rearend revamp, we ditched the stock upper and lower control arms for SVE tubular units made from heavy-wall tubular steel. These are far stronger than the flimsy, stamped-steel Ford units that are notorious for inducing wheelhop.
The SVE units aren't just made from stronger material—they're leagues ahead of the stock units, thanks to Energy polyurethane bushings and grease fittings that make greasing the units a breeze. They're also beyond affordable.
A quick note about the grease supplied with the control arms—be sure to use this special polyurethane bushing grease most commonly found in the small packets from Energy or Prothane. Also, don't forget to liberally spread it throughout the entire surface of the bushings for the best performance.
When it came time to install the rearend components, we paid a visit to Stephens Speed Shop in Martinez, California, where long-time racers Ken Stephens and Jeremy Stanton handled the wrenching. While installing rear end components isn't rocket science, correctly setting the gear backlash can be tricky and is better left to someone with experience. We've seen too many gearsets burn up in short order from improper backlash.
In a matter of hours, Stephens Speed Shop had the withered, old components out and the new stuff installed. Another benefit to ordering parts from LRS is their unparalleled customer service and tech support. We had several questions during the install and their techs were only a phone call away. Follow along with the photos as we take you through the rearend revival process.
Here's to the first step of putting our smog-legal power to the pavement. We're keeping the next installment under wraps for now, but Hang tight. We've given you a hint of what's to come.