1955 Kurtis 500SX

Roadster
Chassis number: SX-001

The cars built by Frank Kurtis enjoyed overwhelming success at the Indy 500 during the early 1950s. At the 1953 race, 21 Kurtis cars finished in the money, and 56 entries were Kurtis-Kraft, though not all qualified. Cars built by Kurtis won Indianapolis in 1950, '51, '53, '54 and '55 and filled out the top 10 places in the other years.

He proved he could be successful in the racing arena, but the question remained as to if he enjoy the same success selling sports cars to the public. In 1949, he created an aerodynamic two-seater and produced 36 examples before selling his design to Earl 'Mad Man' Muntz, who stretched the wheelbase into a large four-seater.

In 1951, Kurtis created the 500KK kit chassis. It had a tube frame, solid axles and torsion bar suspension. These kits were designed to carry a number of fiberglass bodies, from Glasspar, Woodill, Allied, and Victress of have the minimalistic Indy configuration with fenders as an add-on. The chassis was available in sizes that ranged from 88 inches to 100 inches. Power was from a wide range of engines, including Ford flatheads, Cadillac V8s, and Chrysler's new Hemi.

In 1954, a complete version of the KK became available, known as the 500S, with aluminum body and cycle fenders. In total, 21 examples were built. These vehicles proved to be very competitive on the racing circuit.

In an attempt to cater to a larger market, Kurtis tried again with a Corvette-like roadster, the 500M in 1954. This model had a fiberglass body with recessed side panels, often in contrasting colors, and steel panels around the passenger compartment. Kurtis produced 25 examples of the 500M before production ceased in 1955. A joint business deal with McCullough proved disastrous and bankrupted the company. Kurtis ceased building cars in 1957.

It is believed that 12 500SX chassis were completed and generally agreed that six were sold as rolling chassis and four as kits. Four 500SXs were reportedly completed by the factory. In a similar fashion to Bill Vukovich's 1953 Indy 500 winning chassis, they had solid axles and four torsion bars, which were individually adjustable for ride height and handling. Wheels were Halibrand magnesium, and the cars had a quick-change rear end, disc brakes, Borg-Warner or Jaguar four-speed transmissions, and a choice of engines.

Different from the earlier cars, the left suspension bracket was able to rotate while the right was fixed firmly in place. The battery and fuel tank were moved as far back as possible to create the best possible weight distribution. The frame was a fully tubular space truss, widened at the cockpit for FIA sports car rules. The body was from aluminum panels that could be removed quickly with Dzus fasteners. The passenger side of the car was the only side that had a door. The total weight was a mere 2200 pounds and the cost was in the neighborhood of $6,000 without an engine.

Chassis SX-001

This example was ordered new by Albert Hosking of El Monte Cadillac in California. The build was chronicled in the February 1955 issue of Hot Rod magazine. SX-001 was later sold to Mickey Thompson, the racer who at one time held almost 200 FIA International and USAC national speed records.

Thompson and Jerry Unser raced SX-001 with its original Cadillac motor until Thompson's Pontiac sponsorship led him to change it in the late 1950s, and the car has been Pontiac-powered since then. SX-001 was raced by Paul Cunningham into the 1960s.

The current owner discovered the car in 1996 and commissioned a ground-up restoration in 2002 to exacting standards. The car was found complete, but without an engine and transmission. The search for a correct motor turned up what can only be termed the Holy Grail for this car, which was bought from a noted Indy 500 collector who had saved it for just such an occasion.

Frank Kurtis built an Indy roadster for the Firestone Tire and Rubber Company for high-speed testing in 1958. The engine was a one-off Pontiac motor built by Chicago race engineer Ray Nichels. A limited number of the engines were planned for racing, but production never went past the original unit. It is a 370 cubic-inch OHV V-8 with Hillborn-injection and a dry sump. There are gear-driven Offenhauser water pump and oil pump, Iskanderian camshaft and roller lifters, polished and ported heads, big valves and stronger springs. Also, there are high-compression pistons, steel main bearing caps, Vertex magneto and a magnesium front timing cover, oil pan and rocker covers.

The body is completely original. There is a Borg-Warner T10 transmission, and leather upholstery, and has been fitted with modern safety equipment, including a built-in fire system, fuel cell, kill switch, rear rain light, and safety belts.

In 2011, the car was offered for sale in Monterey, Ca, presented by RM Auctions. It was estimated to sell for $800,000-$1,000,000. As bidding came to a close, the car had been sold for $500,000, including the buyer's premium.

by Dan Vaughan

Roadster
Chassis number: 3

Los Angeles mega dealer Bill Murphy purchased this rare 500X Kurtis sports car in August 1955. It is serial number 3 of 6 500X cars built by Frank Kurtis and the Kurtis-Kraft Company. Sam Hanks, an Indy driver and employee at Bill Murphy Buick, was the car's assistant engineer, crew chief and pre-race shake-down driver. In the two years the car raced - September 1955 through September 1957 - it scored nine overall wins and eighteen class wins at tracks throughout Southern California from Torrey Pines to Riverside. Murphy competed in the Del Monte Trophy race in 1956, the final year of the Pebble Beach Road Races.

The Murphy Kurtis has the same basic design feature of the Kurtis Indy roadster of the era - 4120 chrome moly tubing for the frame, 4-bar torsion suspension, hand-formed aluminum panels and Halibrand quick change rear end and magnesium wheels. A 364 cubic-inch Buick nailhead engine with Hilborn fuel injection supplies the power and is coupled to a Jaguar 4-speed XK-140 transmission.

The 500SX sat at Murphy's dealership for two decades until it was purchased in 1979 by Rich Siefried. The Kurtis resumed its winning record at the 1980 Monterey Historics and it also won the Pebble Beach Cup.

This example has its original Hilborn-Injected Buick Nailhead engine, Jaguar 4-speed transmission, and Halibrand quick-change differential. It also has its original drive train, body and frame members with only fresh paint and upholstery added.

Roadster

Frank Kurtis was born in Crested Butte, Colorado, on January 8th, 1908. He learned metal shaping skills at a young age in his father's blacksmith shop, and later worked under legendary designer Harley Earl while at Don Lee Coach and Bodyworks in Los Angeles. The Depression ended his tenure at Don Lee and he began designing and building cars on his own. From the late-1930s to the late-1950s, Frank Kurtis became America's most successful racing car constructor. He built about 1,100 midgets (including kits) along with 128 Indianapolis race cars, both of which dominated the sport. Kurtis-built race cars won the Indianapolis 500 in 1950, 1951, 1953, and 1955.

This 1955 Kurtis 500SX was the fourth 'SX' manufactured. The first six cars, built as rollers not kits, carried an 'SX' designation. The remaining few 'kits' manufactured probably were Xs. This example was 'reportedly' the only LWB model produced.

In late 1955, this car was purchased from Frank Kurtis (Kurtis Kraft) by Joe Zidar of Denver, CO, and it was known as the 'Zidar Special.' The car was raced primarily on the West Coast at such tracks as Riverside, Pomona, Laguna Seca, and as far East as Las Vegas.

The aluminum-bodied car is powered by a 321 cubic-inch V8 engine and uses Hilborn mechanical fuel injection. The on-board hand pump pressurizes the fuel tank and primes the injection system. The wheels are a pin drive, Rudge style knock-off, made of magnesium and were manufactured by Halibrand. The brakes are four-wheel disc plus one hydraulically operated disc emergency brake. Solid axle front and rear are used with a quick-change rear end.

Roadster

This 1955 Kurtis 500 SX was sold to the Cambell Brothers (boat manufacturers) in the LA valley. Instead of using the Sutton body, a mistrace body was fitted. The car was later rebodied as the 'Alligator' and won the 1965 SCCA C modified class with Hooper driving.

The Kurtis Kraft 500X began in the mid-1950s and was the successor to the 500M. The basis for the 500X was from the KK500C Indianapolis car. The car rested on a wheelbase that measured 96 inches and was powered by an American V-8 engine. The transmission was a four-speed Jaguar unit with Zidar adapters. The entire package was clothed in aluminum panels that were easily removable thanks to the Dzus fasteners. The cycle fenders of the 500S were eliminated. The design was aerodynamic and lightweight.

In total, there were an estimated 12 500X cars built. Half were rolling chassis without the engines. Four were built as kits.

by Dan Vaughan