Racing to Bonneville with the Simon Kilger Erickson Roadster Part 2: Safety First

Racing to Bonneville with the Simon Kilger Erickson Roadster Part 2: Safety First

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The Southern California Timing Association (SCTA) has stringent safety regulations with which builders (fabricators) must comply. The SCTA’s mission is to provide safe and friendly Land Speed Racing (LSR) events at the Bonneville Salt Flats and at El Mirage Dry Lake. One thing that a lot of folks don’t realize is that SCTA has coordinated racing at Bonneville for more 61 years and, over the years, they have learned a lot about driver safety. The rules are in place to help make sure that racers stay safe.

For this reason, Simon, Kilger and Erickson also want to build the safest roadster they can, using the latest in driver safety equipment and roll bar design while meeting the specifications of the SCTA rulebook. Further, Al Simon has some tricks he has learned over the years building Bonneville roadsters and this roadster should be one of his safest.

Simon and partner Mike Kilger continue making steady progress on their ’29 Ford custom highboy, paying close attention to the safety regulations as they fabricate the internal roll cage around the low-profile driver’s compartment, drive shaft tunnel and add support bracing where needed in the floor. To keep the project moving forward, the team spends a few late nights fabricating with their Syncrowave® 250 TIG welder and Millermatic® 350P MIG.

Installing the Driveshaft Tunnel

The ’29 highboy now features a 3-speed Lenco air-shifted transmission. Kilger chose this model because it allows the driver to maintain both hands on the wheel for greater control as the roadster tops out across the salt fats. After the team installed the transmission, work on the flooring cross members can begin—with special attention given to the driver safety.

An SCTA rule regarding drivelines states there should be a 360-degree metal sling or protective covering securely mounted over the front 25 percent of each section of the driveshaft to prevent dropping or excess whipping in the event of breakage of the driveshaft or universal joints. This rule is intended to prevent a broken driveshaft from entering the driver’s compartment or hitting the ground.

To meet this specification, a driveshaft tunnel cover must be fabricated. Three rings separated by ¼-in. curved plate will connect to cross members in the floor. Matching the material, a 1/8-in. thick, 1- x 2-in. square piece of mild steel stock is rolled to design specifications and then welded to the adjoining cross members. Simon used a band saw to cut the cross members in the locations where the rings will be welded. After the tunnel, Mike will fabricate a cover for the rest of the transmission that will seal the firewall and floor together.

To ensure square and level fit up, Simon clamps the work piece to a stationary I-beam in his shop prior to welding. Several quick tack welds with the Millermatic 250 hold the rings to the cross members.

The Millermatic® 140 Auto-Set™ also provides smooth, spatter-free starts through Miller’s exclusive Smooth-Start™ technology, improving weld quality and decreasing the need for spatter clean up. This feature helps Kilger make numerous quick tack welds on thick chassis components or thin sheet metal for the body without the cleanup time.

The Millermatic 140 Auto-Set is an affordable, entry-level MIG welder for rod builders with a home shop. Considered the simplest new all-in-one MIG welder in the industry, the user simply has to set the wire diameter and material thickness. The patent pending Auto-Set technology automatically sets wire feed speed and voltage to achieve optimal welding results. Not available on competitive units, Auto-Set technology benefits welders of all skill levels as it allows them to focus on their welding without worrying if their machine is set up properly.

For advanced body and chassis work, a larger machine is recommended. Fortunately, Auto-Set technology is also available on the Millermatic 180 Auto-Set, The Millermatic 211 Auto-Set with MVP™ and the Millermatic 212 Auto-Set MIG welders.

Next, Simon uses the Syncrowave 250 to finish TIG welding the rings to the adjoining cross members. Repeating the same process, Simon fabricates the second and third rings.
Two of the rings here are TIG welded into place around the driveshaft. Note the distance between the shaft itself and the mockup of the driver’s seat. The driver sits low, creating an aerodynamic profile, which minimizes drag. This, however, puts the driver about 3in. to the left of the driveshaft. The ¼-in. curved plate will be installed between the rings to complete the tunnel after the roll cage is welded in around the drivers seat.

Cage Fabrication for Roadsters

According to regulation, the driver is enclosed by a roll cage constructed from 1-3/4-in. DOM tubing with a wall thickness of .134-in. It is designed to work with a 5-point safety harness, requiring the installation of several mounting brackets.

The shoulder hoop seen here wraps around a mocked up driver’s seat, (placed for measurements), and connects to the firewall hoop at the front of the car. These first elements are critical to get the dimensions right for the rest of the cage.

(Kilger also plans to fabricate an all-aluminum seat, watch for it in part III of this story.)

A closer look at the front of the firewall hoop shows just how low the body of the ’29 will sit in relation to the engine and drive train. Swing pedals will mount from the fire wall.


To create a ridged base for the down-bars of the roll cage to rest, Simon uses the Syncrowave 250 to TIG weld these ½-in. plates, which bridge the front cross members to the chassis.


Simon built the remainder of the cage around the driver’s compartment from 1-3/4-in., .134 wall DOM tubing.


Just in front of the rear differential the down tubes of the cage are welded to a 1/2-in. plate. This plate adds weight, where the driver’s seat will be mounted. As part of Simon and Kilger’s design, the center of gravity is located here for maximum stability and power directed to the ground.


Next, the dash rail is installed over the front of the cage. Note the down-tubes on the left side of the cage. They are welded to the curved plate that now completes the driveshaft tunnel.


This view shows the rear cross member, which was also designed to add weight, keeping the rear wheels down on the salt. Al Simon fabricated the cross member from 1/4-in. plate boxed steel, which will also be filled with lead shot, bringing the weight up to 150 lbs. for the cross member alone.


Before stopping for the day, the team installed these 13-in., 4-piston stainless steel brakes that will bring their salty joy ride to a safe stop.

Stay tuned for Part III of this story, when the team finishes the pulsed MIG fabrication of the aluminum hood and cockpit panels and delicately TIG welds the stainless fuel and water tanks. Watch for a short follow-up on its opening run!

Updated: June 28, 2018
Published: June 26, 2009