Your Tech Questions Answered
What Is This BS?!
Q What is backspacing, and how do I measure it on the wheels I currently have so I can get new ones?
A Backspacing is the distance from the back edge of the rim to where the wheel mounts to the axle. To measure, lay your wheel down with the outside (the side you see when it’s mounted on the truck) toward the ground. Lay a flat bar across the wheel, and measure from the inside of that bar to the surface that mounts to the axle. This is your backspacing.
Offset is the distance from the centerline of the wheel to the wheel mounting surface of the wheel. If the mounting surface is toward the outside of the wheel from the centerline, it is considered positive offset. If it is on the axle side of the centerline, it is negative offset.
One confusing factor is that the width of a wheel is measured from inside the wheel mounting bead on one side to inside the wheel mounting bead on the other side.
The trend for a long time has been to get wheels with very little backspacing and/or negative offset. I think it is important to try and run as much backspacing as possible, as this reduces the stress on your wheel bearings. This is complicated by tire size, where the tire swings as you turn, and whether the tires will clear suspension components and steering.
Give Me Liberty (Lift)
Q I have a ’12 Jeep Liberty Sport and I want to put a lift kit on it, but I can’t find one anywhere.
A Daystar (www.daystarweb.com) has a spacer kit for the Liberty that will give you 2 inches of lift.
Q I just bought a Warn winch off my girlfriend’s dad for my Chevy. It has cable on it and works fine, but I wasn’t sure if there was a best setup for a winch in deciding on cable or synthetic rope.
A No, there is not a best. Cable guys love the resilience of metal cable. It is less affected by dirt and grit like rope can be, and it lasts a long time. But it is heavy and can kink and be damaged. Plus, metal cable can rust and get sharp wire frays that can stab hands.
Synthetic winch rope guys like the light weight and ease of use. Being lighter, it is easy to throw and drag through deep mud. But UV rays can reduce its life expectancy.
I run both, I appreciate both, and I realize both can be dangerous if not used appropriately. Always wear gloves no matter which you decide on.
4-Link 4 Weight
Q I know that a four-link suspension flexes better than a leaf-spring suspension. My question is will a four-link have the same load carrying capacity as the leaf-spring suspension it replaces in a truck? Thanks.
A The load carrying capability of a suspension is determined mostly by the spring rates of the suspension. A coil spring and a leaf spring can both carry a large capacity. The four-link suspension is simply a way of locating and controlling the movement of the axle: The spring holds the weight, and the shocks control the movement.
Though a four-link suspension can flex very well, it doesn’t always flex better than a leaf-spring suspension. A lot more is determined by the geometry of the link suspension and what is being used for springs. A lot of big trucks have a linked suspension and use airbags as the spring, so yes, it can support a large capacity of weight. Going to a higher spring rate can often reduce the ability for the suspension to flex. I think we’ll see an air-spring suspension in the next few years on Chrysler’s heavy-duty trucks, similar to what the automaker offers on its half-ton. But I’m not sure if it will go up to the 1-ton and beyond, or just the 3⁄4-ton.
I think most companies go to leaf springs for load capacity because they can build them with a progressive spring rate. This means the springs flex less as weight is added. Coil springs are not usually built this way and are more difficult to build with a progressive rate, as the wire diameter/wrap needs to vary over the body of the coil. Leaf springs allow a better range of load weights, whereas coils are designed more for a smaller range of capacity.