The NORAD Pro FWD Toyota Celica is breaking new ground in many areas of FWD racing technology. Among the innovations Chris Rado, Bob Norwood and the NORAD crew are introducing, the driveline design is most significant. Most DNFs at drag events in the last couple of years have been attributed to driveline failure and occurred in the high-horsepower FWD classes. NORAD team technical director Bob Norwood says the team has found a solution to this problem.
"We decided to start with a clean sheet when it came to the driveline of the new car," Norwood explains. "The current crop of 'transaxle' transmissions isn't really working because the transmission isn't designed for drag racing. Shifting is awkward and slow and the durability is questionable. I decided we'd start with a bulletproof transmission with a proven record in high-power applications and then work back from that starting point."
The DrivelineNorwood's choice, the Lenco five-speed planetary transmission, has a first-class pedigree in drag racing and is renowned for its strength and ease of use. Pro Stock and Pro Mod racers have used this transmission for years, so there's no doubt they can handle the abuse. It can be shifted with levers, electrical solenoids or by pneumatics. Each shift can be adjusted to speed it up or soften the gear change to minimize the shock to the tires. Hundreds of ratios are available and these units are simply bulletproof.
Next, Norwood made the Lenco work in a front-wheel-drive application. The solution was amazingly simple in its design and should prove to be unbreakable in actual racing conditions. First, a 32x16-inch tire was used, with the option of using a 31x14-inch tire at NHRA events. Second, the differential and final drive assembly had to be extremely strong to handle the high-rpm launches the huge front tires would allow. And third, the entire driveline was mounted as low as possible in the chassis to maintain a low center of gravity and minimize weight transfer on the launch.
After much discussion and analysis, Norwood's team decided a Funny car-style rear end was the best way to transfer the drive to the front wheels. Team Engineer Shawn Fischer explains,
"The key factor in our decision was strength. The loads the tire size is capable of generating meant we had to go overboard on the driveline to maintain reliability. We decided to run a Ford 9-inch rear end and utilize a real four-link suspension to give us control over the geometry."
This decision raised other issues, such as how to mount the rear end in the correct position to transfer the drive to the wheels, and how to get the drive from the output of the Lenco to the upside-down-mounted Ford rear end. The answer is, once again, an object lesson in simple, yet creative, engineering from the NORAD technical team.
The trickery starts with the custom billet-aluminum bell housing. Carved from a solid block of 6061 T6 aluminum by master machinist Tommy Todd, the bell housing is designed to be as compact as possible and still house Norwood's unique slipper clutch system. (More on the clutch later.) The one shown here is the prototype and isn't SFI legal, but testing is under way to get the final version certified and completed by the time construction is finished.
Between the bell housing and the Lenco, a billet-aluminum 'spacer-section' also created by Todd allows the rear end to be mounted low enough to maintain the crucial geometry and ride height at optimal levels. He also machined a custom input shaft for the Lenco that's lengthened to allow for the spacer. Bolted onto the rear of the spacer is a standard Lenco CS2 five-speed planetary transmission with the reverser mounted on the rear. The Lenco is lighter than it looks, thanks to magnesium casings and titanium internals.
Transferring the drive to the rear end was the next problem and Norwood's experience with oddball projects in the past paid dividends at this point.
"I've run into the same issues with a few of my Bonneville land-speed record cars and the easiest and strongest way to solve the problem was with a 'V' drive system and a short driveshaft," he says.