i am getting ready to start building my chassis for my 37 chcy truck. What i am curious about is opinions on the most appropriate size tubing for crossmembers. I am going to purchase my bender this week and want to get the correct dies. I intend on using 2x4 tube steel for the rails and was wondering what thickness is most common. I have looked at many post but just have not found the info that i am looking for. Thanks in advance guys
1/8 inch (.125) is the most common thickness and works just fine. I have seen box tubing that is .120 and I would not be afraid to use it. Cross members depends on what you are planning if you are going round tube and making an X type cross member in a square tube frame 1" x 1/8 is what I would use. For cross members like for coil over mounts or shock mounts I would use 2 or 3" tubing. Your choice from cross members is dependent on what type of cross member you are using.
Building the frame is my favorite part of the project. I like to use 3/16" wall rectangle tubing. It has a slightly larger radius on the corners, which I like, and you can drill and tap it to easily bolt small brackets and such to the frame. Yes, the frame will be heavier, but I think worth the trade off unless you are building a racecar. The weldments will be much stronger and the overall stiffness will be much greater. Hey, it is the foundation of the car. Front crossmember for straight axle spring perch should be 3" x at least 1/4". Rear crossmember, use the 2x4 tube. X-member, I used 1-1/2" DOM x.095 wall for single tube, 1" x .125"wall DOM for stacked double tube X-member. Here are some pictures of my 27 roadster frame. A lot different than yours will be, but maybe you can get some ideas. Hope this helps.
I agree with jaw22w's post above regarding the main frame rail material thickness and the reasons why. Ray
Jaw22, I defiantly don't hate your idea of using 3/16" wall tubing, it is probably overkill strength wise (I always used 1/8") but most of our hot rods are way off on sprung/un-sprung weight ratio, this should add weight down low and emphasize it on the rear tires. Should make the cars ride better for sure. maybe what it looses in power to weight ratio it will make up for in traction.
It doesn't look to be 2x4, he didn't say but looks like 2x3 so the 3/16 is a good way to go..If 2x4 then 10ga [.135] wall or 11ga [.115] wall is sufficient..
I never stopped to figure it out, but there are only about 35 feet of 2x3x3/16 tubing in my frame @ 5.59/ft. equals 195.35 lbs. Replace that with 2x3x1/8 @ 3.9 lbs/ft equals 136.5 lbs. So, 58.85 lbs heavier. I think that the added strength and stiffness is well worth the 58 lbs. How many HP's are 58 lbs worth? You could do a similar calculation on 2x4 and I'll bet you would come out with the same range of gain. I think still worth it to go with 3/16"
10 ga. 2x4 96" unsupported span with 500# of wt in center. Deflection is 0.0601 11 ga. 0.0664 3/16 2x3 0.1152 3/16 2x4 0.0464 As you can see, the height of the sidewall is where benefit most. That's why a lot of frames tapper at the ends to save weight as the flex is in the middle. x members and crossmembers help with the twisting and sideways deflection.
For the threaded holes in 10-11 ga. I prefer to drill and insert a nut and weld the the nut in and tap before putting in bolt, nut will shrink slightly and may end up with galled threads. The solution I like the best is thread inserts but the can be kind of costly for a one off build. http://www.avdelusallc.com/products/nutsert.shtml#tools
I thank you for the replies. I guess what i am visioning is 2x4 for the rails and i am looking to do an upper and lower tube for the x member i was just curious as to what size the tubes should be. for the ex i am thinking 1 1/2 inch is probably the right size. Any thoughts?
I'm kind of cornfused,your buying a bender for square and rectangular tube? Tough bending for sure.Now if your buying a bender for round tube maybe I can help you. I had a JD squared bender for years, bought two different sizes and bent all my tube with it. I bought a 1 3/4 die set. Bought some scrap 1 3/4 x .063 chrome moly from a chassis shop.Bent the moly ,sliced it in half with a bandsaw. Used half of the curved part and half of the straight part as a sleeve for the 1 3/4 dies. That gave me a new bending set for 1 5/8 tube. Bought another piece of Mild steel 1 3/4 that was 1/8 ,.125 wall and did the same thing and used that for bending 1 1/2 tube. My second set of dies were 1 1/4 and I would sleeve them to 1 inch. This works best if you keep the die sleeves clean and almost polished. I added tabs to hold the sleeve in the die sets. Good luck.
Yes, 1 1/2 11ga is good, thicker is ok because weight down low on a street car is a good thing. I like your logo, I crewed for Irish Jack Murphy and was there when Jimmy Shampine didn't put his rear engine car back in the trailor after warmups. That car has to be one of the baddest racecars ever to have been built, it needs its; own room in the Hall of Fame.
The Shampine RE car is up the street from me. Jamie Moorr just redid the Radical offset this summer google it As far as the square tube i am not bending that it will be cut and welded. The crossmembers are going to be bent.
1946caddy is correct, you definitely should use 2x4 tubing, not 2x3, from there it is your choice if you want to use 3/16 wall to gain some rigidity in your frame. Depends on how you plan to drive your ride when it is finished.
If it helps, I build all of my cages out of 1 1/2", .120" wall DOM tubing, I also used it for my cross members in my '28.
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