Drag Racing Discussions > Front Engine Dragsters
Potential FED Build
rooman:
Apart from the other reasons noted above, the biggest advantage in using 4130 is that by using .058 wall for the main frame rails you can slip fit decreasing diameter tubes to step the rails down from 1.5" at the shoulder hoop to 1.375" in the engine bay and then 1.25" for the front of the frame.
Roo
lake_harley:
Thanks again for the additional input and suggestions. I can understand that 4130 construction is preferred for many reasons, including the convenient telescoping tube ability. I haven't decided to go 4130 or DOM just yet, but if building with .120" wall DOM, can transitions from one diameter tubing to another (1 1/2" to 1 3/8" for instance) be done with a butt joint and a stepped sleeve that has at least .120" wall at the smallest end? That sleeve would end up being 1 1/4" at the big end and 1 1/8 at the small end OD, with a 7/8" ID all the way through. I do intend to order the SFI book and that will likely clear up many/most of my questions, but for now I'm just considering options.
Thanks.
Lynn
dreracecar:
Why are you making more work for yourself??? Even doing things for myself --my time is not free
wideopen231:
^^^ agree. Its so much more simpler with molly.
Piece of advise.Design around what you think is extreme you will want for car and build towards that chassis wise,then put in combo you want and you will have room to grow if you want latter. Speed is a drug and the more you get the more you will want,to a point. Myself I have never found that point.LOL Just its easier to do once then do and have to redo for another step.
lake_harley:
OK....I concede (as I hang my head in shame), 4130 is the best way to go for numerous reasons and I should quit trying to take shortcuts or pinching pennies. I do wonder about my bender and dies being up to doing a nice job on .058" 4130. I have to pull out my bender and check, but I believe the 1.5" die I have is for 5.5" centerline radius bends. I don't know if it is too tight (no inside mandrel) to bend without kinks or ripples. I guess the only way I'll know is to get some tube and try it out.
The bender I have is a JD2, and if I recall from conversation with dreracecar on another website (the HAMB) that it isn't exactly the preferred bender to use anyway. I guess I'll just have to get some 4130 of a couple sizes and do some test bends to answer that uncertainty for myself. I do recall from previous use that my 1 3/4", 6.5" centerline radius die created an unacceptable, rippled inside radius on 16 Ga. HREW tube. I don't recall ever bending anything under .083" with the 1.5" die, but I fear the tighter radius on it will have the same problem when bending 4130.
I know I keep saying it, but I do appreciate the suggestions and advice from everyone.
Lynn
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