[d_animator]

"....The J-car was a radical machine in most respects. The only familiar item at first was the thumping great "side oiler" 427, the 500 HP iron block V8 from the Mark II. An automatic transmission was part of the original plan. So was its wedged shaped body, one of the earliest attempts at aeordynamic down force. What the car is most remembered for, however, was its lightweight chassis, racing's first significant application of aluminum honeycomb...."

".........That there were subsequent J-Cars was itself something of an anomaly, for many had low confidence in the concept. Ford Initially planned its l967 endurance program around the now faithful MK II. But at the first race of the new year, in February at Daytona, the MK IIs went out with identical transmission failure; in any case, Ferrari's new P4 had shown unexpected speed. In an atmosphere of near-desperation the J-Car was put through intensive development. The most prominent change was aeordynamic. Completely new nose and tail sections increased striaghtaway speeds by up to 10 mph, so for the first time the J-Car showed more top end than a MK II (about 215 mph vs 211 mph). The car was less stable than before, but the drivers said they could race it. To differentiate it from the despised J-Car, someone had hand painted a new designation, "MK IV" on the new nose. On April 1 at Sebring, driven by Andretti and McLaren, in a stirring battle it defeated the 2F Chaparrak to winits first race."

MORE IN DEPTH....

It was the technique of using honeycomb-sandwiched aluminum which motivated the J car. This technique used half inch honeycomb aluminum panels which had to be bonded together. The first J car would use this honeycomb aluminum to form a central tub chassis similar to the GT40's. The final specification for the car adhered to the Appendix J regulations for race car construction.

Since Ford Advanced Vehicles had been sold off, the J Car was produced by Fords subsidiary Kar Kraft. Ed Hull headed construction of the experimental J-Car program with assistance from the Brunswick Aircraft Corporation.

The first J-car, called J-1, was completed in March of 1966. It's chassis, which weighed 86 lbs, supported the fiberglass body and 427 engine. J-1 made its first public appearance at the LeMans trails that year. It weighted 2660 lbs which was nearly on target with the 300 lb weight reduction Ford was looking for. At such a weight it was not surprising that the J-Car took the fastest time at the trials. Unfortunately, the J-Car was sidelined for the rest of the 1966 season to help the GT40 Mark II's effort.

After the 1966 1-2-3 Le Mans win, Ford decided to invest more money in the J-Car program. A second car, made up to Can Am specification, was made to help sort out the aluminum honeycomb chassis. Unfortunately, this car was completely destroyed during testing in an accident which claimed the life of Ken Miles. Driver error was never considered.

After a weak performance at Daytona, where transmission problems plagued six Mark IIs, Ford reluctantly continued the J-Car program in preparation for Ferrari's 330 P4. They worked on chassis J-3 and J-4 in preparation for Sebring. During this time, Roy Lunn, Chuck Mountain and Phil Remmington worked on the J-cars extensively. They created a new body for the chassis which incorporated a longer front nose, a Can Am style tail section and a new roof line to accept a rear window. During this transformation the J-Cars officially became known as the GT40 Mark IV.



Hope this helps out!!!! I will post that small block question again...if you want to read it, it is in the small block talk section...

Thanks for the welcome!!