The Professor draws a bead on new wheels
Contributed by Jon Knapp
For the last month, most Americans have been preoccupied with getting themselves ready for the holidays. Across the country, malls have been packed with shoppers, while airports and highways were jammed with travelers trying to make it home, all part of the normal hustle and bustle at this time of year.
Although he most certainly took time to celebrate Christmas with his family, Pro Stock icon Warren Johnson's focus for the last six weeks was on preparing for an entirely different season the 23-event NHRA POWERade Championship circuit.
Of primary concern to the GM Performance Parts Grand Am driver was the rule change mandating the use of beadlock wheels on all Pro Stock vehicles in 2004. As far as "The Professor of Pro Stock" is concerned, it was a welcome move.
"This is a change that has been coming for about six years," said Johnson. "In the past, the rule stated that any car exceeding 200 mph was eligible for beadlock wheels. I broke the 200-mph barrier in 1997, and in the years since, the performance of the Pro Stock category as a whole has improved to where you now see a 200-mph top speed on almost every run.
"At those speeds, the screwed-on tire and wheel combination makes these racecars relatively unstable. This really manifested itself in Columbus, where we had two rookie drivers end up on their roofs. With safety in mind, Goodyear took the initiative, working with the teams and the NHRA to make sure this change was enacted for the 2004 season. This was a move made strictly in the interest of safety, and I applaud it."
Due to the combination of the tremendous power produced by today's factory hot rods and the outstanding traction provided by current tires and racetracks, teams have been forced to find a way to secure the rear tire to the wheel in order to prevent it from breaking loose from the rim, especially over the last few years.
In the past, Pro Stock competitors would accomplish this by inserting screws through the outer edge of the wheel into the area of the tire contacting the wheel, which is known as the bead. A beadlock wheel takes this concept one step further, mechanically locking the bead of the tire between a metal ring and the rim itself, a design which, as Johnson describes, is much more secure.
"A beadlock wheel encapsulates the bead area of the tire in a mechanical lock from the inside, outside and inner diameter, so it cannot move in any direction," Johnson said. "With the old method of screwing the tire to the rim, you were depending on an interference fit between the two sides.
"One of the potential problem areas in the old design was the screws not penetrating the bead bundle adequately, which could lead to the bead separating from the wheel due to the centrifugal force, with the tire eventually coming off the wheel. Over the last two years, both Kurt [Johnson, teammate and son] and I have had five incidences of tire and wheel separation, and we know other teams with similar experiences. We're all fortunate that no one crashed because of it"
As with any modification, an improvement in one area can have a negative affect on another. However, in this instance, W.J. believes the trade-offs are well worth it.
"The two primary disadvantages of these new wheels are the extra weight and cost," Johnson said. "However, you can adjust for the weight, the improved tire wear will help offset the increased cost, and quite frankly, you can never put a price on safety. Whatever the cost might be, it is insignificant as opposed to the safety margin we will have."
Since the 2003 season came to a close last month in Pomona, Calif., Johnson has been hard at work learning the intricacies of the new set-up, with test sessions in Atlanta, and Bradenton, Fla. Even by his high standards, the results have been impressive, with W.J. unofficially bettering his personal bests in both elapsed time and top speed. More importantly, he has garnered valuable information on the new combination, and is pleased with what he has seen so far.
"The amount of traction we have from this tire and wheel combination is significantly better than we had before," Johnson said. "As a result, it's not prone to spin the tires down track, making it much more stable.
"The lack of tire spin manifests itself in the remarkable lack of tire wear. In the past, we would wear off between two and two and a half pounds of rubber on every run. Now, we're using about a quarter of a pound, and you can feel how much more steady the car is in the lights.
"For example, during testing I made one run deliberately out of the groove, trying to see if the added contact patch would have any bearing on the car wanting to pull one way or the other.
"With one tire completely out of the groove, and the other just on the edge of it, I drove the GM Performance Parts Grand Am to the 1,000-foot mark right up against the wall, then simply pulled it back into the middle of the lane and finished the run in the center of the racetrack. As I told Goodyear, the car is so stable that they will have to start giving the drivers No-Doz to keep them awake during the run."
Although this change should make the tuners' assignment slightly easier, Johnson cautions that a thorough off-season testing program will be required to fully take advantage of the benefits and be properly prepared for competition the tightly-packed 2004 Pro Stock field. As expected, an extensive schedule is already in place for the GM Performance Parts crew prior to the season-opening K&N Filters Winternationals in mid-February.
"Although this change has been made only to further improve driver safety, it will naturally have performance implications," Johnson said. "The tuning window appears to be considerably bigger, because we now have an adequate amount of rubber contacting the track, possibly as much as 10-20 percent more. The car does want to wheelstand more, and it takes a lot more clutch and gear ratio. However, these are mechanical things for which you can compensate based on your particular car.
"The best way to fully get up to speed on this combination is to make as many runs as possible on a variety of racing surfaces, putting a greater emphasis on off-season testing. We've already tested at Atlanta and Bradenton, and plan to take our GM Performance Parts Grand Am to at least two or three other tracks before the season starts to bolster our notes entering 2004. We have our work cut out for us, so I guess you could call getting a handle on this combination an early New Year's resolution."
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