I had just arrived at New Smyrna Speedway on the Thursday test day before the annual Governor's Cup races late last year. I was standing in turn one right next to the fence, not twenty feet from the track when Frank Kreyer went flying by, left front tire flattened, with his throttle stuck. He proceeded to hit the wall as hard as I've ever seen a race car hit.
The car continued around the outside wall shedding parts along the way and came to rest at the end of turn two. Frank got out, injured, and walked down the track and along the way, he threw down his HANS head-and-neck restraint in frustration at having destroyed a perfectly good race car.
The only good thing I can say about that is that he was wearing a H&N restraint. That most definitely, in his opinion, saved his life. Two other drivers died in Florida in 2013 from hitting the wall at asphalt racetracks. They did not have on the required equipment and their families lost a loved one.
This is not a discussion about wearing a H&N device. It is to announce the beginning of a study as to why throttles stick. I will personally be talking to experts and racers about situation they have seen and/or experienced where the throttle stuck on a race car.
There are two primary areas to look at, one being interference with the throttle arm or linkage that moves that arm, and the other concerns the mechanisms on the carburetor locking the butterflies open where the driver can't return them to closed.
I've heard several stories already about how the both of those situations have happened, but I'll wait to get all of the information from the appropriate experts as well as firsthand accounts, before I make my report. I don't think I have ever seen anyone address this situation, not that it hasn't, but I'm getting involved now.
Most everyone will agree that having a stuck throttle going full speed on any racetrack is right up there with the worst things that can happen. In almost every case, the car is destroyed in the process and if the driver is lucky, he is only injured. Countless drivers have lost their lives over the years from having their throttle stick open.
If there is anything that you need to pay very close attention to, it is the operation of your throttle linkage and carburetor. When the carb is off the car, you can operate the throttle arm from closed to full open several times to see if anything prevents it from closing. Nothing should impede a quick and friction free movement to closed.
Once the carb is installed, you should look over the entire linkage from pedal to throttle arm to see if there is anything that could interfere with the operation going from idle to full open throttle and back.
When the air cleaner is placed on the carb, again we need to inspect the area above the throttle arm to make sure there is proper clearance. The top cover of the air cleaner should have a stop under it on the threaded bolt coming up from the carb so that the bottom of the air cleaner can't be pushed down onto the throttle arm. The recess on the bottom of the air cleaner should be centered on the throttle arm too.
A few years ago, various companies offered a brake pressure operated kill switch that would kill the ignition if a certain level of brake pressure was induced. This was intended to help stop the acceleration when the throttle stuck. In Frank's case, he braked so hard that the left front tire deflated. I noticed that when I saw him go by. At first I thought that was why he could not turn in, but that was not the case.
Maybe it's time to rethink installing those devices. It may not keep the car from impacting the wall, because the event happens so quickly, but it would reduce the velocity of the car and minimize both the damage and the chance of injury to the driver. It is a simple device that is relatively cheap. In the 2013 Coleman catalog, it lists for $123.53. Let's see, a little over $100 or a $40,000 race car and motor? That's a tough decision.
The fact that you can never predict when your throttle will stick or how, the fastest and most efficient way to immediately deal with the situation and mitigate the damage is to be able to quickly kill the motor to stop the acceleration into the wall. The kill switch is the answer. You make the decision.
If you have comments or questions about this or anything racing related, send them to my email address: Bob.Bolles@sorc.com, or mail can be sent to Circle Track, Senior Tech Editor, 9036 Brittany Way, Tampa, FL 33619.
How to Find a Good Car to Purchase
I love reading your articles! I have been a crew chief for my friend's Dirt Mod for years now and have finally scrounged up enough to put a Sport Mod together. I know there are tons of chassis out there but how do you go about choosing from all these different types?
Obviously, I need to watch for bent ones and so on, but what are some good things to look for when choosing a frame in general?
You might look for a chassis built by a reputable builder. Does it win races where you race? Then look at how the chassis has been maintained. Talk to the previous owner and see if it has been crashed hard, had clips replaced, etc. Those things tell you something about how hard a life the chassis has had.
You will need to see what the front and rear suspensions are built like. Are they adjustable for moment center location, rear steer, etc. Are there any cracks or bends in the chassis or control arms? And, how old is the chassis. The older it is, and the more it has been raced, the greater the chance that it will have damage or is just plain worn out.
The best cars to find are those where the previous owner bought the car new, raced it a limited number of times, never wrecked it, and now wants to get out of racing. You can usually pick up the car and many spare, also new, parts for cheap.
Also remember that a long time active racer will not sell you his/her best equipment or the winning setup that helped the car get those championships. Mainly just take your time and look at a lot of cars before deciding. That one special deal will come along.