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ABS and Big Tires: A Bad Combo?The service manager at the Ford dealer where I bought my truck recently told me that if I install tires larger than 32 inches in diameter, the antilock braking computer on my '01 F-150 would malfunction and possibly cause a reduction in braking performance. Is there any kit or modification I can make to keep the ABS working?Ray GarciaPalatine, IL
Ray, the service manager is both right and wrong. Installing larger-than-stock-diameter tires will indeed cause a decrease in braking power and quality. The increased weight of the larger tire and wheel (compared to the OE wheel and tire) and the reduction in brake leverage over the tire will both decrease the stopping power of your truck. How much less brake force you'll have depends on the overall tire diameter you install - the taller the tire, the less brake leverage. If it were our truck, we'd seek out a set of high-performance brake pads and shoes to go along with the taller tires. As to the ABS question, we don't agree with the service manager's statement that taller tires will cause the ABS to malfunction. The ABS sensors on the driveshaft, wheel, or disc rotor detect wheel lock-up, and then the computer momentarily reduces braking force at that wheel to prevent wheel lock-up and skidding - tire diameter isn't a factor in the computer's algorithm. Furthermore, the larger contact patch (footprint) of a big tire provides increased traction and less chance of wheel lock, so the ABS may not even engage during hard stops.
Tweaking Torsion BarsI'd like to install new tires on that are only 2 inches taller than stock. I have seen other Chevy IFS 4x4s that have their torsion bars adjusted to get a taller ride, and I'd like to do the same. Can you tell me how high I can lift my truck by adjusting the torsion bars?Greg HulganVia e-mail
On most torsion-bar-equipped trucks,you can typically raise the suspension 1-1/2 inches by adjusting the preload on the torsion springs. Resist the urge to crank in more than a small amount of lift on a torsion bar suspension because doing so will cause a wealth of suspension and steering geometry problems. Too much torsion bar preload will reduce the suspension's down travel (droop), which causes a reduction in steering capabilities. Also, too much suspension extension will cause the CV joints on your Chevy's front half shafts to bind, leading to an early failure. Too much lift via the torsion bar drastically alters the suspension geometry, mainly the camber angle, which causes uneven and rapid tire wear and handling problems because the tires' tread aren't planted squarely on the road surface. If you still intend on lifting your truck an inch or so by adjusting the torsion bars, make sure you have the truck professionally aligned when you're through.
Special Stroppe BroncoI have been looking in the papers for an early model Ford Bronco, and I think I may have found a special factory model. The Bronco is a '71 4x4 model that has cutout fender flares that look like a professional/factory modification, a 302ci V-8 engine with a four-barrel carburetor, and a roll bar. Everything looks stock. The owner says it is an old Stroppe Special, but he doesn't have any additional information. Do you know anything about these Stroppe Broncos?Jay PoyserLafayette, LA
Good news, Jay, you may have found a real gem of a 4x4, a long way from its original home in Southern California. Legendary off-road race truck builder Bill Stroppe introduced the limited edition Stroppe Baja Bronco in 1971, and the trucks were produced through the 1976 model year. Sales figures are spotty, but Stroppe estimates he sold 200 Baja Broncos the first year of production, and approximately 150 per year thereafter. The suggested retail price of a Baja Bronco in 1971 was $5,122; the standard Bronco sold for about $3,700. Features of the Baja Broncos, which were based on the Sport Wagon model, include distinctive red, white, and blue paint, a flat-black colored hood to reduce glare, a 302ci V-8 engine with a four-barrel carb and an automatic transmission, a roll bar, double shocks front and rear, rear fender flares, cut-out front fenders with modified flares, 8-inch-wide wheels, a heavy-duty suspension (4,700-pounds GVWR), additional oil and transmission coolers, an auxiliary 10.3-gallon fuel tank, a swing-out rear spare tire carrier, and Baja Bronco nameplates on the body. Some Baja Broncos were further equipped with a rear Detroit Locker, an aftermarket tachometer, an air-conditioning system, racing-style seats and safety harnesses, and a more-powerful V-8 engine. We're not sure of a Baja Bronco's current value, Jeff, but if you've found the real deal, and not a standard Bronco posing as a Baja Bronco, it may be well worth the investment.