SCTA Prepares for Speedweek 2011
Q: Have you ever wondered what it takes to time your vehicle at Bonneville?
A: Below is a little insight into one of the least thought about components that make up the timing system for the SCTA and BNI; miles and miles of wire for each course.
The start of the timing system at Bonneville or El Mirage is a photo cell transmitter and receiver. On one side of the track sits a light source and on the other is a photo cell that receives the light. When a vehicle interrupts the light source to the photo cell, it transmits an electrical signal to the timing system in the timing tower. The first photo cell that is interrupted starts a clock in the timing system and a time hack is taken when each subsequent photo cell has its beam interrupted. The computer takes the times between each given trap and calculates the speed for that known distance. At the other end you receive a time slip with your speed on it. Sounds simple doesn’t it?
Q: Where is the wire stored and how does it get out there on the course?
A: The wire is kept on spools that are about 2’ long and 18” in diameter. Most of the spools and winding equipment were purchased after WWII from government surplus yards. Each spool has about 10,000 feet of wire on it and weighs about 220 pounds. It is laid on next to the course from the SCTA wire trailer or out of the back of pickup trucks off of a stand that allows the spool to freely unwind. When a spool is empty and more wire is needed, a splice is made that has good mechanical and electrical connections and another spool is laid out. This happens from each photocell on the course to the timing tower. At the end of the meet, the wire is rewound on the spools using a winder with an electric motor and then stored in the wire trailer for the next event.
Over time the salt gets into the splices and starts corroding the copper in the wire. Also, the salt will find a path to the copper wire when cars spin out and run over the wire. Most time the friction of the tire over the wire will strip the insulation and the salt will start immediately corroding the wire. When the wire corrodes the electrical signal from the photocell is reduced to the point that the timing system will not see the signal. If this happens during an event, the problem area must be found and repaired before it can continue.
To keep the problems with the wire at a minimum on the salt, maintenance is performed on the wire every few years. This consists of winding the wire from the full spool to and empty one and inspecting all of it. Every splice that is made on the salt is wrapped in electrical tape and immediately cut out. Normally several feet of wire on each side of the splice must be cut out to eliminate the corrosion that travels up the wire. Once corrosion free wire is found, the wire is stripped and twisted together to form a good mechanical connection. The wire is then soldered to ensure a good electrical connection. After soldering the wire, special clear shrink sleeve is installed. Clear shrink is used to examine the splice at a later date. If it is still clear, with no corrosion present, then the splice is not cut out. The shrink sleeve has a sealing layer on the inside and when shrunk around the spice and wire, it forms a water tight seal. This keeps the salt and water from entering the splice and causing corrosion.
On June 25, 2011 a group of volunteers from SC TA clubs gathered together at Mike & Pam Manghelli’s, Drifting Sands Ranch to do the wire inspection and repair. There were 15 volunteers with 7 SCTA clubs represented. They lifted and sorted through 21 spools of wire totaling 38 miles of wire. With three spools being wound and inspected at time, it took 11 hours of steady work to complete the task. Their pay for the day was all the water, sodas and beer they could drink along with a gourmet lunch from the local Coronel Sanders. Next time you receive a timing slip at Bonneville, make sure you thank those that slaved in 100 degree heat to ensure the wire is not an issue during the event.
Mike Manghelli – Sidewinders
Tom Hanley – Sidewinders
Ron Cohn – Sidewinders
Keith Pedersen – Sidewinders
Jim Dincau – SDRC
Jim Jensen – SDRC
Bob Sights – Gear Grinders
Judy Sights – Gear Grinders
JoAnn Carlson – Milers
Greg Carlson – Milers
Bruce Kelly – High Desert Racers
Monte Warnock – High Desert Racers
George Callaway – High Desert Racers
Roy Creel – Super Fours
Jim Dunn – LSR