Original comp cars steering arms

[MAStuart]

Did the original comp cars have to have the steering arms bent for wheel tire clearance. Or was it something they had to do when the reproduction FIA wheels started to get made in 7 1/2 inch. Did they need to get bent with the original 6 1/2 inch wide mag wheels?

[Dan Case]

Yes. The wider the front wheels got, the further the bending had to be. 427 Cobra competition chassis started off with curved steering arms like Cobra racers had been using but it was not enough for 7.5 inches wide so more bend was added for subsequent 427 Cobra street cars.

If you look under a stock Cobra with original 6.0 inches wide wire wheels there is not a lot of clearance between tie rod ends and rims. The cars were designed for 5.5 inch wide steel wheels.

The first magnesium front sprint car design race wheels provided by Ted Halibrand were just 6.0 inches wide. I have never gotten to see how they fit relative to steering arms on cam and follower or rack and pinion steering cars.

The adoption of 6.5 inches wide front magnesium wheels was an interference problem. The wall section widths of cast magnesium wheels are much thicker that the wall sections of stock steel wheels. That increase in wall thickness alone would create a problem. (Note: There was not just one version of six spoke 6.5 inches wide front race wheel. There were several casting patterns and several ways they were machined including how they were machined for brake caliper clearance. I test fit five different versions of original 1963-65 six spoke 6.5 inches wide wheels I borrowed from various Cobras one Saturday morning. My surprises included the offset changed between versions and the amount of space provided for brake calipers changed also. Offset to the outside kept getting greater and space for brake calipers increased. How much? I never mocked up an exact number but front wheels CSX2009 raced on decades ago will not clear the street brake calipers for CSX2165 onward street cars. It looked like roughly half an inch or more would have to be found somehow to clear the street brake caliper. The last pattern made for 6.5 inches COBRA wheels and the way they were machined allowed them to clear any of the street or race brake calipers Shelby American ever used. (Decades ago I got the idea to have one of every version of magnesium wheel used on Cobras to mount on a wall. Once I figured out how many different castings that was I dropped the thought.)

I never found enough pictures to do a race Cobra illustration slide but I did one for 427 Cobras that illustrates the problem. 427 Cobra racers started off designed for left over 1965 versions of the COBRA six spoke wheel from Halibrand. (Somebody in The Shelby American Automobile Club started calling them "FIA" wheels but to Shelby American they were just "race" wheels and they were used on Cobras and 427 Cobras in all kinds of racing. Ted Halibrand named them COBRA wheels in drawings and mold patterns.)

Shown on the CSX30xx car below are the tie rod end dust boots for both sides physically rubbing the backs of 7.5 inches COBRA II wheels. The CSX30xx cars were designed with the previous 6.5 inches wide front wheels in mind and some early racers and at least one CSX31xx street car got 6.5 inches wide COBRA front wheels. Once the 427 Cobra plan changed to 7.5 inches wide front wheels A.C. Cars made increased bends in steering arms.



It is my belief, I cannot prove it, that Shelby American originally dealt with the clearance problem themselves. Early chassis were all made as street cars to which changes were made to go racing. At some point new chassis were made to order as race chassis, allowing some things to be done by A.C. Cars. I have no idea what chassis first came from England with slightly curved steering arms but the CSX213x car photographed for an update of Cobra racing specifications registrations had them based on the pictures taken of the brand new chassis at the time. Those early racers had shallow gentle bends in steering arms.