Until Weld Wheels came up with its new Accu-LocTM system and billet-aluminum center, sprint car rear wheel design hadn't changed for the last 10 years or so. According to Joel Kokoska at Weld, "The initial requests for a change came from the tire people and guys like Karl Kinser. The guys mounting the tires wondered if we could find a way to center the lock ring quickly. That would help them get tires mounted faster. Karl wanted something to make the tire/wheel assembly come out 'more round'.
"The folks at Weld Wheels went to work and came up with a raised inner lip on the wheel rim that positively centers the lock ring and the bead of those big, floppy tires. A 'round' wheel and tire won't bounce at speed, which means the tire spends more time in contact with the track, and more contact time equals more traction. Plus, the lip locates the bead-lock ring and makes it faster to get the 20 or so clamp bolts started in their holes."
There's another benefit to the new design. The new lip, combined with a deeper countersink for the bead-lock bolts, act as a shield to protect the bolt heads and caused another design change that offers even more protection. With the lip in the way, the usual mud cover system won't work. By slotting the bead-lock ring and putting the bolt holes in the ring and attaching springs for the mud cover Dzus buttons into the flat rim surface instead of the lock ring, the wheel cover now does more than keep mud out; it also protects the bolt heads. While it may not sound like a big deal, during a wheel-banging incident the bolt heads of the two wheels act a lot like those nasty spinner blades sticking out of the wheels in a movie chariot race scene. They grind against each other, and the bolt heads can get so beaten up they are almost impossible to remove without major surgery, or the head can actually get torn off. Of course that's a recipe for a leak that'll move you from a big paycheck to tow money faster than Karl's car can pass a rookie.
Another change on the new Weld wheels is in the all-important center. When someone crashes and says, "We broke a wheel," it's usually the center that has failed. Like everyone else, Weld has used a cast magnesium center forever. When they began having supply problems with their casting house, the crew at Weld looked for a solution. Kokoska says, "We changed to the forged, billet-aluminum centers because of supply problems and were able to design the new centers to be as light (as magnesium) but stronger and more cost effective. With our experience in wrought aluminum alloy and forging technology, we can control the quality of the centers better, and we were actually able to lower the price a little bit." Ain't racers ingenious?
The whole system has been torture tested by Karl and Mark Kinser and worked out well. "Well, I've been running Weld wheels for about 15 years now and this is the nicest one it has ever made," Karl says. "I'd been telling Weld it needed to rethink the bead lock thing because nothing centered the tire's bead. This one keeps the wheel and tire centered to each other. It's made a three-piece wheel act like a single unit. They're round to within about .012 inch.
Amazing isn't it? A simple request to make tire mounting easier and more accurate turned into better performance for the racers.