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Frequently Asked Questions
Frequently Asked Questions regarding our Ford parts and accessories - (Click on a question to expand the answer)
Notes: Tire size can vary depending on wheel offset, wheel width and tire tread design. These sizes are based on a 15x8 wheel with 3.5" backspace. These tire sizes are a general guide line because a wider tire or offset rim can cause interference with the sheet metal. A large lugged mud tire will also require more clearance or a shorter overall height in order to clear compared to an All-Terrain tread style. A 2" body lift will generally allow a 1.5" to 2" taller and wider tire to be used. For even more clearance our fender flares can be added and the sheet metal trimmed to clear the tires.
Notes: Tire size can vary depending on wheel offset, wheel width and tire tread design. These sizes are based on a 15x8 wheel with 3.5" backspace. These tire sizes are a general guide line because a wider tire or offset rim can cause interference with the sheet metal. A large lugged mud tire will also require more clearance or a shorter overall height in order to clear compared to an All-Terrain tread style. A 2" body lift will generally allow a 1.5" to 2" taller and wider tire to be used. For even more clearance our fender flares can be added and the sheet metal trimmed to clear the tires. Keep in mind that installing taller tires may require a ring and pinion gear change or the addition of performance add-ons for the engine or both modifications. On models up to 1989 we highly recommend upgrading to stronger later model axles when more horsepower and bigger tires are combined. Larger tires will also affect the ratio that the speedometer reads and thereby may show a slower speed than actual speed.
Our suspension systems are available in stages, so that you can build your suspension in steps, as your needs change or your budget allows. Each of our kits is tested individually, then tested again with each of the upgrades available. The suspension components are matched with one another to provide the best overall performance. This is of the upmost importance in the Twin Traction Beam suspensions. All of the components must be addressed when lifting, otherwise the vehicle will have serious handling and alignment issues. Most components are only available kit form in order to address these issues. This assures you of a great performing suspension system, having all of the components work together.
A performance oriented suspension and a smooth ride-our progressive rate coils offer the best of both worlds. Our progressive coil as opposed to a stock single rate coil; the rate gradually increases as the coil compresses. The upper wraps are softer for a more comfortable street ride; the middle rates are a bit firmer to handle bumps and dips without jarring; and the last few wraps are a higher rate so that they control the up travel to prevent bottoming out.
Since the coils have a softer initial rate they also will deliver more suspension travel than a single rate coil. The softer rate allows the tires to stay on the ground; providing better traction and handling. The progressive nature of the spring also allows for better and more predictable handling by helping keep the vehicle flatter in the corners and limiting body lean.
Stock suspensions were designed primarily for improved road use and safety with little consideration for true off-roading. We know that our customers are outdoor adventurers who travel the back roads and beyond. We consider this type of use and on-road safety when designing our suspensions.
A suspension lift raises the frame and body from the differentials and wheels, allowing the use of larger tires which increases the ground clearance under the axles in order to clear trail obstacles. Attention to wheel travel and overall ride quality is an important consideration in the design of our suspension lifts. The improved traction and wheel travel directly translates into how well a vehicle will traverse any terrain. A vehicle properly equipped for off-road use causes less damage to our trails.
Our shocks are valved 70% rebound, 30% compression. With our suspension systems, the coils are engineered so the shocks aren't needed for compression control. Our shocks smooth out the ride by controlling rebound. They don't overheat because they aren't trying to control compression.
Conventional 50/50 valved shocks use equal pressure on both compression and extension. That creates a choppy ride, overheating shocks as they try to control compression instead of letting the spring do it's job.
Duff suspension components are designed, tested and most, built in house. Our design team strives to build the highest quality parts while keeping the customer's budget in mind. Our components are built for easy installation using common hand tools and require little or no welding. Our suspension systems are built using the best materials available and are laser cut for quality and a precision fit. Parts are formed and welded on site by our certified welders and finished with a tough powder coat finish for longevity.
As a norm, we don't recommend it for a fully street truck or one that spends a great deal of time at highway speed. Reason being, when you combine progressive coils with the top heavy weight of the vehicle it creates a great deal of body roll when taking turns. We have many people do it, with and without the addition of a custom way bar or custom fitted Currie Anti-Rock Sway Bar.
Quite honestly, it depends on how you use your rig. If it is primarily a street rig, we don't recommend it unless you have already taco'd or pretzeled (technical terms) factory linkages. A knuckle flip is usually a good solution in this case. Spherical rod ends or heims as they are commonly called do make more noise and each state varies on their restrictions, so before ordering heim steer for your street rig please check your local/state laws.
95% of Duff products will match some sort of factory mounting spot on the vehicle. This is usually to locate where a bracket goes. You will use the bracket as a templete to drill the rest of the mounting holes in the vehicle. We also usually recommend welding the brackets into place or vice versa depending on what you have access to at the time. Please take into consideration that although we strive for proper fitment and build our products in fixtures for consistent accuracy, the majority of vehicles we are working on are over 30 years, some older than 45, there are going to be some inconsistencies from vehicle to vehicle. Please take this into consideration when installing, it may take a couple hits with a big hammer for perfect fitment. ;-)
No. Pan 3642A is designed to work with a later model 302 with the dipstick hole in the block or the 289/302 timing cover dipstick.