Superchargers, nitrous, intakes, and exhausts are all great power adders; but if the power goes up in smoke, the effort and money spent were all for not. When rebuilding our F-150 SuperCrew, named Project Sinatra, we knew power would be a large area of concern. Sending the power to our truck was going to be an Auburn Gear High Performance limited slip unit, with a Precision Gears 4.10 ring and pinion bolted to it, and cooled by a Concept Pattern (C&P) differential cover. With our nearly 32-inch tall 24-inch wheel and tire combo on the Ford, the 4.10 gears will help us to get out of the holes much faster. Meanwhile, the Auburn Gear High Performance limited slip will ensure the extra added power will actually motivate the truck into a forward line. The key is to start with a trusted shop and quality parts when swapping gears and a differential in your truck, and so we contacted the pros over at Diff Works in Riverside, California, to perform the install. Known for its complete axle kits, Diff Works wasted no time tearing into the 6-year-old truck and had us back on the road before lunch. Lifted, lowered, or even stock with some bolt-on power adders, your truck can benefit from a new set of gears and a high-performance differential. For more information on these products and Diff Works capabilities, check out the sources box.
Project Sinatra was about to receive some added street performance by simply adding a Precision Gear 4.10 ring and pinion set to help the F-150 launch harder than ever before. A major must when swapping gears is the replacement of the old hardware. We ordered a Precision Gear overhaul kit that included new axle bearings, a pinion bearing, seals, bolts, and a differential gasket. | 
Auburn Gear High Performance Series limited slip was our diff of choice for the Ford. It will make sure the extra power that we have big plans for actually makes it to the ground. Be on the lookout on coverage of this in an upcoming issue. |
Arriving early to Diff Works in Riverside, California, the shop owner and gearhead Steve Post began by placing the F-150 on a lift, removing the wheels and tires, removing the 10 diff cover bolts, and then draining the old fluid. Then, he removed the U-joint cap bolts so he could swing the driveshaft to the side. This allowed him access to the front pinion nut that he busted loose with an impact wrench. | 
After releasing the axle pin, removing the two axle bolts per side, and using a screwdriver to free the differential, Steve knocked the old pinion out of the axle cover. Next up, Steve used Chemtool cleaner to soak the inside of the rearend and a sanding wheel to clean the diff cover mounting surface. |
Using a press, the new Precision Gear pinion bearing was perfectly pressed onto the Precision pinion. | 
Before the new pinion was installed, Steve knocked the new pinion race into the rearend. |