Building a 25-hour endurance racing FFR GTM[Racing Adventures]
[Shell Valley Classic Wheels, Inc.]
What it Takes to Build a 25-Hour Endurance Racer
Posted August 17, 2016
Transforming a Factory Five GTM from a component car for the street into full-on endurance racer has put me through more twists and turns than a competition road course. Most of us think that race cars are just race cars, but this one grew up to have a mind of its own!
When the word got out about the project, volunteers from all over the country, by way of online forums, chimed in to lend a hand, becoming fast friends that I never even knew I had. It became a passionate affair of friendships, competition, ideas, local high schoolers, fun, enthusiasm, tech support—the list goes on and on.
I have seen more than 100 volunteers pass through my garage door, all of them earnestly and willing helping to mold this creation. Many people say that their build becomes a part of the family. But I would say this GTM created a family!
I should point out, though, that I had some competition history that helped all this happen. I had done some dirt circle track racing back in the ‘90s for about 10 years. That’s where I developed my racing contacts. When the car was delivered, all my friends said, “Let’s make it an endurance road racer!” It was like the old days of Sprint car racing, when we made our own parts.
Also, when traveling, the GTM has attracted a following that has led to free lodging, temporary workshops and remarkable memories that could never be scripted. Who would have guessed that over 1,000 men, women, and children crossed the threshold for a chance to sit in the carefully crafted seat and not want to get out? The excitement of people slithering into the cockpit has its own special place in my heart, unleashing a big smile that could not be washed away with the most toxic of cleaning solvents.
The attraction is partly because the car was modified for a center-steer application, making it easier to drive. Moving the driver to the middle of the car was a safety feature that proved very exciting to pilot. With endurance engineering in its design, the dash looks like a fighter plane ready for its next tactical mission, provided with switches, gauges and gadgets perfectly laid out for night racing. Modifying the car’s frame for center steering required cutting out the backbone, and transferring loads to the outside by adding new tubing that connects the pickup points for the front and rear suspension. The rack is a Unisteer part changed from a left-hand to a center setup.
Coming into its own, this thoroughbred demanded more and more involvement. It grew out of the adolescence of budget building, making something out of nothing, and then went onto accumulate a respectable track record, thus making car-builder history for Factory Five Racing.
What’s next? I will be the first to admit that the GTM is a sexy and unique car, one which can be built in the privacy of your own home. But a top level competitive race car? Go figure. I still don’t quite believe it myself.
The adventure took another twist in becoming a very desirable car to drive. The GTM grew up in the unlimited classes of NASA and SCCA, jockeyed by some very talented locals, tallying 94 percent podium finishes and four championships. Our humble garage build is now catching the eye of some professional drivers that just can’t stay away. Today, there seem to be more professionals grabbing the reigns than you can imagine. When the first pro driver was attracted to the car, we realized that we’re actually better than we thought we were.
The 2015 season has been an exciting one, and our first year in a pro series running in the GT class with the United States Touring Car Championship (USTCC). Piloting the GTM, drivers Mike Holland (a five-year veteran with our team, PDG) and Ken Dobson (development driver for Scuderia Cameron Glickenhaus) scored three First-place wins and one Third-place finish in the first four rounds of racing. So we’re leading the points and now have a strong possibility of winning the GT championship!
Our primary Series is the Western Endurance Racing Championship, an amateur competition of day- and night-racing where we are Second in overall points and will likely finish behind the efforts of Truspeed, a professional Porsche Cup team. Our final effort is the finale at Thunderhill Raceway Park at the 25 hours of Thunderhill, the longest closed circuit road race in North America. In the 13 years of this race, the GTM and team of all volunteers are the only recipient of the prestigious “Spirit of Thunderhill” award (for rebuilding the car after it caught fire and then completing the event).
Getting down to the details of endurance racing, it’s not necessarily about running 10/10ths, but instead reliability and strategy. Surviving an endurance race comes down to two key words: preparation and planning. That means researching the right components, and not using throw-away parts. We purchase for the long haul, since we can’t afford to buy cheap. For instance, the stock C5 Corvette hubs only last about 20 hours in racing conditions, since the plastic races melt and the bearings go bad. For twice the money, but four times the wear, we went with SKF units that last two years and two 25-hour races.
The Unlimited class provided the perfect platform for all the volunteers. A center-driver configuration allows for installing a 22-gallon fuel cell on each side of the driver’s seat, as done in Ford’s GT40 back in the Sixties. All told, 44 gallons of 91 octane pump gas gives this steed the ability to run 2.5 hours without fueling. (We’ve found that race gas runs hotter, and with 25 percent lower mpg, and the engine computer prefers standard fuel anyway). Our custom-built sway bars and engineered Bilstein shocks are a proven combo over the years, reducing lap times by more than 10 seconds. Having outgrown the C5 wheels and DOT tires, we’ve moved up to three-piece CCW race rims.
As for the engine, this GTM started out with a used LS1, an ASA-prepared V8, but now switches between race series with either LS3 367/480 or LS3 367/525 crate motors. The 480 gets better mpg for endurance racing, and meets the USTCC’s power/weight rules. But the higher powered 525 is better for faster, shorter duration events at Thunderhill and in Utah. We have plug-n-play setup for quick swaps between races. The engines were provided by a local dealer, Chase Chevrolet, where we display the car on weekends and get lots of enthusiastic onlookers (especially younger ones who are amazed by the cockpit).
Both engines are backed by the same Mendeola 5-speed sequential dog box, which doesn’t require actuating the clutch to shift. Axle reliability and custom control arms were engineered by Myraceshop.com. This firm (headed up by one of our drivers, Mike Holland) also fabricated five different wings for various levels of downforce. We’ve found more downforce is better in the turns, which is where we often beat the faster cars.
The custom glass windscreen with wiper provides a great visual platform for rain and fog conditions. Bajadesign lights up the night with 38 LED fixtures. The gullwing/lambo-style doors are trimmed and strutted for quick driver changes and egress in the event of an engine fire (don’t ask me how I know this).
The initial setup sported front C5 brake calipers, installed both front and rear, but quickly outgrew them. Next step was to install StopTech fronts and rears. This made for better stopping and longer life in the annual 25-hour race. To manage the brakes, one of our volunteers built a brake bias that can be read instantly by the driver to make corner-to-corner adjustments to fit his or her driving style.
Airjacks provide the lift for tire changing, while machined rims mated with a circle-track type of spacer indexes the rims for quick tire changes. The Factory Five’s fiberglass main body is cut behind the doors to provide quick access to the engine compartment. The inventory of several different wings has been made by volunteers throughout the campaign.
I look back at all that has happened and there just isn’t enough space to tell all the adventures and many memories of people we have met, places we have stayed, support, and the generosity. I know one thing, though: this was never a dream of mine, but surfing this wave has been “Reality to the tenth power!”