Sometimes it makes sense to redefine oneself to demonstrate innovation and to diversify into other realms. In the case of Jeff Gamroth, shifting from his comfort zone on the tarmac to the unforgiving and brutal terrain of off-road racing was a step in a different direction than he had been accustomed to. However, this decision is one that would showcase the versatility and capabilities of his race shop, Rothsport Racing.
Jeff has raced Porsches in endurance competitions like the Daytona 24 hours and the Sebring 12 hours, along with NASA, SCCA, and PCA events since the early 90s. In 1998, he established Rothsport Racing in Sherwood, Oregon, to serve the Porsche racer and enthusiast. His knowledge and experience prepared him for a daunting endeavor, the National Off Road Racing Association (NORRA) Mexican 1000 Rally, a race that no Porsche had ever won.
Off-Road Odyssey
This journey began in 2014 when Jeff and Cameron Healy decided to construct and campaign a pair of identically prepped, rear-wheel drive 1989 Porsche 964 911s to race in the Mexican 1000. According to Jeff, they chose the 964 because of its robust chassis and its reliable engine and driveline. These traits are essential to survive a grueling, 1,000-mile race through the desert. Cameron’s car dubbed the “Desert Flyer” donned a yellow hue while Jeff named his crimson ride the “Red Sled.”
Powering through the Sand
Like any competitor attempting to finish the Mexican 1000, it’s imperative to make good power and transfer it to the tires reliably. The heart of the 964, the 3.6-liter, air-cooled, flat six-cylinder M64 engine, was refreshed in preparation for the race. Using a MoTeC M84 engine management system to regulate fuel and spark delivery, the M64 engine was calibrated to make 320 horsepower and 275 lb-ft torque.
This is a 22% increase in power and 17% more torque compared to the stock output figures. To handle the increased output, a 964RS flywheel and clutch bolted to the crankshaft transfers the torque to the input shaft of a fortified G50 transmission, which was equipped with a ZF-style, mechanical limited-slip differential.
Since air-cooled Porsche engines rely on engine oil and heat sinks as methods of heat exchange, Jeff routed -12AN lines from the engine up to an aluminum oil cooler positioned in the rear window that was custom made from acrylic. Flame resistant insulation protects the lines in case of an engine fire.
The oil cooler mounts to the roll cage bracing behind the driver’s seat. A puller fan draws cool air from within the cabin through the oil cooler core. Once heat is exchanged, the fan expels the heated air through a hole cut in the plexiglass rear window.
Fortified Chassis
Since the rally runs through the desert terrain of Mexico, ensuring that the 911 had adequate ground clearance and rollover protection was a must. Preparing for the desert began with gutting the chassis and welding in an FIA-compliant cage. The network of chromoly tubing and braces shroud the occupants while also providing additional chassis stiffness. Within the latticework, a pair of OMP race buckets with harnesses position the driver and co-driver firmly in place.
In front of the driver, a Momo steering wheel mated to a Rothsport quick release hub receives steering input.
In the footwell just below the roll cage, a floor mounted Tilton 600 Series pedal set replaces the factory assembly.
A 911 with Ground Clearance
The 964’s exterior remained largely original, save for chromoly bumper bars at the front and the back and a 911SC RS wing atop the engine bay. A quartet of Hella driving lamps was secured to a rally light housing mount to the hood between the headlights.
The 964 chassis rides much higher than Porsche engineers had intended to ensure ground clearance, thanks to a set of long-travel adjustable coilovers. Even so, the Porsche rides much lower than trophy trucks and buggies that compete in this rally.
Finally, the wheel wells were filled with Braid 15x7-inch wheels equipped with Hoosier Gravel Rally race rubber. A skid plate mounted between the front tires helps to keep the nose out of the dirt, especially in the case of extremely uneven terrain.
First Outing
It was finally time to leave the tarmac and kick up some rooster tails in Mexico. The NORRA Mexican 1000 kicked off in Ensenada and put the Porsches to the test. For this first effort, the Rothsport Racing goal was to have fun and finish the race. As one would expect, things did not go flawlessly for the Rothsport Racing crew. However, even when the dust settled, the team managed to finish third and fourth in class, a respectable finish for a first time effort. They learned volumes about the terrain and noted the changes they would need to implement in order to remedy shortcomings for the next trip south of the border.
Chassis Changes
Challenges faced at the 2017 race gave Jeff a clear direction for necessary modifications to be made in preparation for the next year’s race. The first major change made to the chassis was the angle of the skid plate. They got stuck the first year due to the skid plate angle. To remedy this, the front chassis structure was modified to a more aggressive angle. The modifications required the fuel tank to be reduced. Although there were concerns about a reduction in range, the modifications and new skid plate angle, along with the reduced weight proved effective at reducing the chance of the nose getting stuck in the sand. Increasing the ground clearance was the next issue, so the coilovers were upgraded once more to permit even greater ride height and adjustability.
The Desert Punches Back
Even after collecting data from the first trip in the desert, it was not always possible to preempt every single outcome. On the first day of the 2018 Mexican 1000, the driver side trailing arm snapped during the stage. Jeff and his crew got the chassis up on jacks, and he changed the trailing arm and got back on the trail. Further into the race, a significant suspension change enhanced the handling and helped to improve the 911’s manners. On day four, just ten miles outside of Loreto, the transmission bell housing cracked, forcing them to get towed fifty miles through the desert to the next closest town. There, the Rothsport team swapped in a spare clutch and transmission.
One-Two Finish
At the end of the fifth grueling day, the "Red Sled" pulled into San Jose del Cabo and crossed the finish line, second in the Vintage Stock Production Cars class behind its sister, the Desert Flyer. This one-two-finish marked the first time that a Porsche ever won at a 1,000 mile desert race. Add to this fact that these 911s are almost 30 years old makes the win all the more remarkable.
Story by Richard Fong
Photos by Antonio Alvendia
If you enjoyed Jeff's "Red Sled," you can find additional Porsche-related content at porsche.fcpeuro.com, as well as more build features like this one, here. If there's anything specific you would like to see, or if you have any questions/comments, leave them in the comments section below.
