How Can a Throttle Stick?
speedvision.com
Daytona Beach, Fla., May 16 ? Although there has yet to be a published report on the accident that took Adam Petty's life at New Hampshire International Speedway, garage area speculation seemed to center on a stuck throttle. In response to a question about sticking throttles during a teleconference Tuesday, Mark Martin, driver of the No. 6 Valvoline Ford, explained what happens:
"That question came up from my wife, first thing," Martin said. "'If the throttle sticks, don't you turn the switch off ? the ignition switch off?' The answer to that is, 'Yes.' If the throttle hangs wide open and you're at a racetrack where it affords you enough time to take your hand off the steering wheel and reach over and shut the ignition switch off, then that's what you do.
"What happens is, it's impossible for a driver to take his hand off the steering wheel and switch the ignition switch off when he's so close to the corner when he finds out the throttle's hung.
"If he gets right down to the turn-in point of a corner of a place like New Hampshire, lets off the gas and it stays going, all you really do ? and all you'll ever really do ? is grab two hands full of steering wheel and hold on tight right before you hit.
"That's common. You just can't reach over and shut the switch off at every racetrack, every time. It's based on how much time you have between where you figured out the throttle was hung and your ? you know ? wall impact.
"I don't know if you understand that completely," Martin continued. "If you let off the gas a hundred yards from the corner and it's stuck, you'll just reach up and turn the switch off, and it won't be a big deal. But if you let off the gas and you're already turning into the corner and it's stuck ? it's too late to have time to turn loose of the wheel. You're basically going to get ahold of the wheel and brace yourself for what's fixing to happen.
"Typically, the most common reason for sticking throttles is the air cleaner base lays over the top of the carburetor and usually is in pretty close contact. The accelerator linkage itself ? that mechanism ? is pretty close to that air cleaner base. Usually, you have them hang on that base.
"Sometimes you have a failure in the carburetor that will cause one to hang ? a little less likely. And sometimes you'll have the joints themselves ? we call 'em heim joints ? that allow the rod and mechanism to all work, you'll have them bind up or galled up. Typically they'll stick the throttle, but not wide open though. It'll hold it at half throttle when you let off, and you're able to manage the racecar and get it back in without crashing it.
"Those are the normal scenarios that can cause a hung throttle."
Asked if sticking throttles are freak occurrences, Martin replied:
"It is not a freak thing with the first one that I described," Martin said. "It's something that happens ? depending on your team and who's working on [the induction system] ? it might happen once in five years to an individual driver to more often than that.
"I've had some hung throttles ? not hung particularly wide open ? as recently as a month ago. I'll repeat, the throttle didn't hang wide open. It hung maybe a third open. But that was that condition in the linkage area up around in that air cleaner base. That's typically what causes your problem, and you can't see it because it's down underneath there. So your engine guy has to feel it ? you know, feel the throttle when he puts the air cleaner on. He has to reach and open the throttle wide open and let it back off, which our guys always do. But there's a slight amount movement in those cars, and things tend to shift just slightly when the cars are running. And sometimes what worked in the garage won't quite work once it gets out on the racetrack.
"Now that's only speculation now. I mean, I'm just answering your questions. I have no idea what happened in Adam's case," Martin concluded.
According to the No. 45 Petty Enterprises crew, the throttle was not stuck on the racecar after the accident. ? Bill King, Senior Editor, RACER and Associate Editor, Champ Car (Photo: Allsport/Robert Laberge) |
