The primary intent of the Buckstop Kit is to improve off-road traction and handling for trucks destined to work often as Fire Brush Trucks, Work Trucks, or Overland Campers. Buckstop trucks will be loaded in the 14,000lb to 19,500lb GVW range and used both on and off highway. At the core of the kit are four 41″ traction tires that replace the original six dual rear wheel style tires.
The problem is that OE dual rear tires lack traction, are stiff, cannot be aired down, are not available with a substantial off-road traction tread design, are more difficult to navigate through technical obstacles and narrow paths, and are prone to debris becoming lodged between the rear tires. In addition, stock trucks offer limited ground clearance.
The engineering design parameters are limited by available tire sizes for the weight capacity and OE front and rear axle widths. The kit is designed on those foundational elements with a desire for minimal additional changes. Buckstop has found the optimal suspension lift to be 3-1/2″ at full weight load, full articulation, and full turning. Body Extra wide Front Fender Flares are a necessary component to cover the entire tire similar to OE fender designs. All in all, it’s the best balance.
The Kit is engineered with each component integrated to with the next to achieve optimal performance as possible while converting from dual rear wheels to four single tires. Clearance for the big tires is achieved with a minimal suspension lift and large cut-out fender flares that keep the center of gravity as low as possible. Track width is roughly 92″ at the outside and consistent front to rear. Fender Flares are an integral part of the kit providing complete tire coverage from road spray and also replacing and covering parts of the body that are cut away for tire clearance.
The Stage 2 kit is a Premium Kit that replaces essentially every suspension component in the front of the truck. It includes all of the same items as stage one with added components to ensure perfect performance.
- Adjustable Track Bar – this allows the front axle to be adjusted side to side under the truck to be perfectly centered. From the factory, the axle is not centered. Front payload weight also effects this alignment.
- HD Sway Bar – Buckstop exclusive product, the HD sway bar allows full turning radius without any tire rub. It is also heavier duty than stock and provides a more stable ride under sway from wind or hard cornering.
- 2-Stage Soft Stop Springs – Buckstop engineered product, the 2-Stage spring kit adds a second set of springs to the front of the truck as a certain compression level is attained. At extreme levels of compression under typical driving situations, the dual spring pack will halt upward movement of the suspension completely. This does the job of a bump stop, but without the harsh engagement given by the OE rubber stop.
41″ tires and maximum payload are the fundamental design elements of the Single Wheel Conversion Kit. At Buckstop, the chassis is fully loaded and subjected to extreme articulation and turning conditions to determine suspension and body modifications required for tire clearance.
Suspension upgrades are necessary for two reasons – the first to gain tire clearance and the second to improve flexibility. Buckstop has found the ideal suspension height tobe 3-1/2” allowing ideal up and down travel of the suspension and room for the tire to turn under the body. There are several methods of achieving the suspension lift and Buckstop has considered everything necessary to achieve lift AND improve performance. The steel spring system is a comprehensive kit that replaces essentially every OE component in the front of the Ford. The Hydraulic system is an amazing kit that utilizes 4 struts controlled by a microprocessor. Details of the suspension systems are discussed in the “Stages” and “Hydraulic Suspension” tabs.
In order to neatly fit the monster 41″ tires under the body, the internal frame, fender, and body require cutting and trimming. Buckstop’s uniquely designed 8” wide fender flares are a special part of the puzzle that cover the cut-out portions of the body and also completely cover the tire from road spray. Buckstop has recently invested a great deal of time and effort to design a beautiful fender complimenting OE styling ques. It looks like it came straight from the Ford factory. Attachment is hidden through existing holes for OE Fender Flares. Flares are shipped in un-finished fiberglass. Final coating/paint is required.
Behind the headlight, a significant piece of the inner frame structure must be removed for tire clearance. Buckstop provides a replacement structure that bolts into place allowing room for the tire – no welding required.
Tires: With a 19,500lb GVW, rear axle capacities approach 14,000lbs requiring a tire capacity up to 7,000lbs each. The 335/80R20 is the perfect choice – a “military” style radial tire with excellent handling characteristics under load. It has an off-road tread pattern and can be aired down to match different loads. Tire noise is acceptable at a level equivalent to a standard truck mud tire.
Wheels: The military tire has a higher shoulder than light-truck street tire. A typical street, light-truck wheel will not fit the tire properly and carry the weight. Buckstop manufactures wheels that are designed for the load and the military tire. They track in-line front to rear compensating for the difference in front and rear axle widths of dually trucks. The wheel is single piece construction without extra bolt flanges, spacers, and bolts. Tires can easily be rotated front to rear for even wear without dismounting the tire from the rim.
Choice of axle gear ratio is a matter of vehicle application contingent on load weight and duty-cycle. Low gear ratios are used in vehicles to overcome a lack of torque from the engine and lack of strength in the transmission. A weaker drive train requires lower gear ratios. As today’s diesel engines produce more and more torque and transmissions improve, gear ratios are decreasing. A rear end ratio of 3.31:1 is now available for a diesel engine truck capable of a Gross Combined Vehicle Weight Rating (GCWR) of 25,700lbs. This includes the truck, payload, and trailer. A less tangible factor is the duty-cycle of the vehicle. An F250 that tows a travel trailer 500 miles a year is far different from a work-truck that operates 12 to 24 hours per day loaded to full capacity. Lower gear ratios reduce strain on the system and increase longevity in heavy use, high mile vehicles.
Engineers for F550 and Ram 5500 trucks have determined that a 4.88:1 gear ratio is ideal for the heaviest duty work trucks. They are designed to be busses, tow trucks, moving vans, utility trucks, dump trucks, heavy-haulers, etc. covering many miles a year hauling heavy loads. The Gross Combined Vehicle Weight Rating (GCWR) of a 2019 F550 is 40,000lbs all day, every day.
Considerations for selecting the best gear ratio: An F550 with 4.88:1 axle ratio on Single Wheel Conversion 41″ tires has an equivalent ratio of 3.94:1.
– A Brush Truck or Camper will weigh 19,500lbs at maximum load – half the GCWR of a fully laden F550 and 6,000lbs less than GCWR of an F250 with 3.31:1 gears.
– A 3.94:1 ratio is between the common 3.73 and 4.10 ratios with 31,000lb and 32,000lb GCWR respectively.
Conclusion: Most Single Wheel Conversion Brush Trucks and Campers will operate at a very light weight relative to GCWR of comparable work-truck applications. They will also see a relatively light duty-cycle not being run 12 to 24 hours a day, 365 days a year heavy laden. All considered, most Single Wheel Conversion trucks will live an easy life. The factory 4.88:1 ratio is well within the operating parameters of this application.
Topping off the truck is an extra-wide bumper compensating the increase in front track width. The bumper extends past the fender flares to fend off fence posts, trees, and other obstacles jumping out along the way. At the heart of the bumper are the same features found on standard Buckstop bumpers including winch mount, tow hooks or mount points, trailer receiver, latching winch access door, built-in light mounts, and several options for built-in sirens, speakers, and monitor.
The truck ends up 7-1/2″ higher than stock considering suspension lift and larger tire diameter. This makes accessing the cab a challenge! Buckstop has designed a custom set of Running Board Steps for Conversion trucks that bring the rig back down to earth. The steps are both broader and lower than standard steps. After climbing in and out of the truck a few dozen times, drivers will appreciate the extra boost they get from lower steps. Steps are NFPA compliant using “Fire Tread Plate
Undercarriage protection is available with Radiator, Transfer Case, and Transmission Skid Pans designed to keep branches and debris from damaging the underside of the vehicle. These pieces are heavy-duty construction and fit tightly to the underside with minimal loss of ground clearance.