Project F-150, Part III - Off-Road MagazinePosted in How To on April 18, 2006 Comment (0)
In the last installment of "Project F-150," you read about the addition of a Ford Bedrug bedliner and an A.R.E. Z Series cap. These have worked out great and have been a welcome addition to our truck.
It's time to start improving our F-150's performance. The suspension is a great design, utilizing coilovers up front and leaf packs with shock absorbers mounted outside the frame in back. Their outboard position allows longer shocks to be used and increases lateral stability. The F-150 handled pretty well stock. It didn't handle well enough for us, though, especially off-road. Over washboards, the truck would stutter and lose traction. Larger bumps or small whoops forced us to slow down to a crawl. Please don't misunderstand us, the Ford worked as well as any other 1/2-ton offering available today, maybe even better, but we wanted more. And more is available.
King racing shocks are legendary for their fabulous performance in the crucible of racing. With the popularity of higher-end suspensions, King now offers shocks for the nonracer who wants the same shock absorber technology used in King's race shocks. In the January '06 issue, we did a feature on King's new shock upgrade kit for the F-150. The upgraded coilovers and rear shocks worked so well we figured why not install them on our own truck too? The King coilovers are beefy 2.5-inch units with compression and rebound damping set for the '04-'06 F-150. The rear shocks are a 2.5-inch smooth body design with a piggyback reservoir. The coilovers, out of the box, lift the front of the truck about 2 1/2 inches but can be adjusted by turning the preload ring from the 2.5-inch lift back to the 0-inch lift, if so desired. The rear shocks actually lifted the rear of our truck about 1/2 inch, which was a surprise. The plastic-body factory rear shocks must have been REALLY wimpy! While the coilovers level the truck, these shocks aren't designed to provide more lift. They're designed to be some of the highest-tech, highest-performance coilovers and shocks available for the F-150 that will allow you to double your off-road speed from stock.
Our local dealership is St. George Ford Lincoln-Mercury, located in St. George, Utah. We usually look at dealership service departments with a wary eye, as the technicians and service writers usually don't have much experience, and what they do have is bad. St. George Ford is different. The dealership's service department is BIG, high-tech, and the average tenure of the technicians there is 10 years, so they know Fords! St. George Ford is also a Roush dealership, which means they can install our Roush supercharger for us when we get to that. When we arrived, Travis Jones, the suspension expert, showed us to our bay and went right to work.
The King shock upgrade kit was an easy, bolt-on proposition. Travis put the F-150 on the alignment rack after the shock installation, something you need to remember to do too if you change the suspension on your truck. The stock 17x7.5-inch steel wheels and 235/75R17 Hankook radial tires were really sub par. The tires didn't perform well anywhere, whether the surface was dry pavement, wet pavement, or dirt. Their 30.9-inch diameter was too small for our intended use and looked way too small on the truck. We wanted to use tires that were around 35 inches, but when we did the feature on the King shock upgrade, the 35s we used rubbed a little bit.
They didn't rub much and this could have been fixed with some judicious trimming, but we didn't want to trim anything on this truck. We also didn't want the tires to stick out at all, as we plan on driving this truck on the road as much (or more than) the dirt. Goodyear offers its Wrangler AT/S all-terrain tire in a 275/65R20LT, load range E, that is 34.1 inches in diameter and has an 11-inch section width. This size sounded perfect. The AT/S is a proven tread design that works well on-highway or off. Its snow and sand performance is very, very good too.
The other factor determining how far a tire sticks out is wheel backspace. Our stock wheels had 6 inches of backspacing, which is a lot! Any wheel that had less, though, would stick out farther, especially as any wheel we chose would also be wider. Another problem when purchasing wheels that have less backspacing than stock is that the scrub radius is increased. Picture your wheel with the correct backspacing pivoting around the centerpoint as you turn. Now, picture a wheel with less backspacing. As you move the wheel farther out, the wheel now swings in an arc around the centerpoint. This makes it harder to turn and (usually) will cause your tire to hit the front or back of the wheelwell when you turn. We didn't want this.
We also kind of like 20-inch rims, like most of you. The reason large wheels and low-profile tires work so well on the street is the same reason they don't work well off-road. Flotation is needed, and a low-profile tire doesn't supply much. Our stock wheels and tires had a decent sidewall height and enough flotation. The 275/65R20LT tire had about the same sidewall height as the stock tire did, so we thought we'd give it a try. American Racing makes a great-looking five-spoke wheel called the RT-S in 20 inches. It comes either in black, which we didn't want, or chrome, which we didn't want either. Remember, chrome won't get you home. American Racing told us that not only is chrome the company's most popular finish now, but that new plating processes ensure that the chrome stays on the wheel, even in off-road situations. The chrome is also much easier to clean than any other finish. So, we decided to go with chrome, 20x8.5-inch American Racing RT-S wheels with 30 mm (6 inches) of backspacing.
The wheels and tires look great on the F-150. They don't stick out, nor do they rub anywhere. They don't rub while turning lock-to-lock or when pounding over bumps. The tires are quiet on the highway and work as well in all environments, as we mentioned earlier. The RT-S wheels have a 2,200-pound load rating, which is great for a cast-alloy wheel and is more than enough for our use. The tires and wheels are also true. We went to American Car Care in Hurricane, Utah, which does our mounting and balancing for us, so the folks there could mount and balance the Goodyear tires and American Racing wheels. The combo required very little weight to balance and they don't shake, shimmy, or vibrate on the road.
Our Project F-150 now works great on and off the road and looks better too. There was very little change in the ride from stock during everyday maneuvers on the road. The truck can really move in the dirt now, and it has the ability to soak up the washboard roads that did it in before. It also traverses the big bumps at respectable speeds - we don't have to crawl across the big bumps and smaller whoops. With the change in tire diameter, we need to install lower gears and add Detroit Truetrac limited-slip diffs front and rear. We also need to up the horsepower output of the Ford so it will get up and GO. For that, we plan on a Roush supercharger, which not only adds over 100 hp, but it doesn't void the Ford's factory warranty when installed at a Roush dealership. Stay tuned.