Club Cobra - A thread on the construction of original leaf spring frame

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A thread on the construction of original leaf spring frame

On original cars the main frame tubes are 3 inch. Did they use electrically welded seamed tubing? What was the tubing thickness? I have heard or read it was .090 thick. Is this correct ? Now days I think most use 3 inch DOM .120 wall tubing. That type of tubing and thickness was used for the rest of the frame and body support tubing? What type of welding did they use On the main frame? I would think stick on the main frame and maybe torch to weld support tubing.

Mark

Mark, I have a chunk of a main tube from an original car and it is .090. Large tubes were arc welded. Birdcage tubes were gas welded also shown in Dave Friedman's photos. I believe those tubes were .063 but someone can correct me if I am wrong. Better off using a main tube with .120 wall.

From what I've heard, the main tubes were close to 3", but since they were sourced in Europe they were actually a metric size.
.090 would be close to what they were rated as, since metal guage thickness is pretty universal.
Agree, .120 would be a better substitute and DOM if possible, but very little difference between DOM and ERW .

Thanks for the replies. AJ do you have a link to the Dave Friedman's pictures?

Next question is . The drawings I have shows the main rails as being 98 1/2 long without the end caps. The drawings also show the main rails as being 17 1/2 inches apart to center line of the rails. Is this correct ?

Mark

There are a couple sites hosting Daves photo's. Here's one: https://www.flickr.com/photos/thehen...7628488413505/

Many coupe photo's and lots of info for study.
Larry

Quote:

Originally Posted by MAStuart (Post 1355341)

Mark, The photos of the AC assembly line I have are from an archive book of Dave Friedman's. If you are looking for something let me know and I will see if there is documentation of it and I will email you a scan copy.

The main rail of an original car, second ownership that was hit for the first time, had a length of 98 3/4". Added to that length is the front cap (10 gauge) and the rear wishbone mounting plate (3/16"). Kirkham cars use a 10 gauge plate in place of this which would be better if you have access to a good press brake to do the bend in the heavier plate. The main rails measured 17.50" apart. This came from a very early 289 R&P car so I don't know if there ever was any variation with latter cars.