Altered chassis question

[beargeorge]

I am building an altered useing both  the Mark Wiliams blueprint and the SFI chassis specs10.2  for6.00 =7.49seconds e.t..My question is the rear uprights that connects the bottom rail to the shoulder hoop the one that connects the rearend to the chassis.SFI calls for inch and a quarterx0..58 M.W.AA calls for inch and 3 eights x 095,which one do you guys prefer.

[Paul New]

10.1E calls out 1.375 x .083 wall.

[rooman]

I use the 1.375 x .083 as a minimum.  The altered frame that I currently have on the jig has 1.5 x .095 pressed into an oval configuration the same as Force uses on his funny cars. In fact I had Norm at JFR oval the tubing for me.

Roo

[beargeorge]

Thank You, ROO

[beargeorge]

Thank You Paul

[Van]

The Altered chassis I built last year got 1 1/2 X 120 wall, because it was in stock & 095 wasn't. I had used the same material on my FED when I built it.   058 never

[beargeorge]

All set, i was able to get the 1.375x095 cm from Shapiro Steel,i still dont understand SFI calling for 1.250xo58.Thanks everyone for your help.

[janjon]

Roo, I'm curious how it was ovalized. I recently had to duplicate a semi-streamline shape in some aluminium tubing for pylons for a FM antenna array for MD-500 helicopters; I made a die in an wire EDM that formed a tube into the desired shape with the help of a hydraulic press, is that how  JFR does it? Any pics available?

[Paul New]

I have made round moly tubing oval in my press. I use spacers to prevent the tubing from collapsing in the center whenever I do this I do a couple of samples to figure out the correct thickness to press the moly to

[rooman]

JFR have a flat die set up for their Trumpf CNC press brake and simply squeeze it in that. I presume that they have programmed the press stroke to end up with the desired result which is a tube with a 1.5" minor axis to match the frame rail diameter. The flat surface on the sides is only about 5/8" wide.

Roo 

[dreracecar]

Don Long started doing that many years ago for wing struts on alc. dragsters.  Since the tubing was thinner than RE uprites, took a lot of testing on the material. Alloy comp.  was a player (it needed % copper) and he dial indicated (because the tubing is not perfect) to index it in the press. I still have some of the rejected pieces(fractures) that I use to make decor tables and such