Chromoly tube for ladder bars

BigYellowIron

BigYellowIron

Diesel Tech
Joined
Aug 22, 2007
Messages
1,400
Going to do a set of single bars for my brothers truck. I was thinking about using 1.5 x .120 chromoly. Think this will be strong enough. The people at the steel place told me it would be more than enough.
 
I used 1.5"x .250" mild steel for my tubing and its done well... so far. I know CM is stronger, but not sure it would twice as strong? I would say do it with 1/4" wall CM, but I know its expensive too...
 
How long are they going to be?

If it were me I would run 2x.120 or even .188 wall 4130 that should be good.
 
The price of DOM is high as HE!! We dont want to spend the money on DOM. 1.5 x .120 is what we can get easily here as well as the threaded inserts. I have used just 2 inch pipe but it will bend. I have been told that chromoly is 40%+- stronger than regular tube.
 
i used 2" seemless cm with .5 wall and they are stout but a little on the heavy side
 
i used 1.5" od stainless steel pipe with 1/4" thick wall. does the job and looks good too. i think i am going to go with 2" od this year.
 
I dont know, the CM was 1 1/2 x .120 was 7 bucks a foot and DOM 1 1/2 x .250 was 13 bucks a foot.
 
2" .5 wall DOM. I have seen 1.5" schedule 80 pipe(2" OD .2" wall) Flex badly and bend the other set. No issues with the 2" .5" wall. Kind of heavy, but oh well.
 
bubba2400 said:
2" square tubing, light, inexpensive (not cheap), and very strong.
Click to expand...
thats a good thing to use to I use 2x2 .120 tube for mine but there not a mile long so that sorta helps.

If your going to use 1.5 .120 wall you could get some 1x.125 flat stock and weld on the top and bottom of the links that should stiffen them up pretty good and allow you to use the smaller diameter tube
 
Resistance to bend and flex is the big thing.

Funny thing is, most people don't realize that all of the steel alloys have virtually the same elastic modulus, irrespective of alloy or heat treat condition. You can make a coat hanger out of 1020 or 4340 or 300M, and it'll still flex in your hand much the same.

Now if you're talking about actually pulling something apart, then alloy and hardness have everything to do with it. But in the case of traction bars, it's almost always about flexure, so choose any of the alloys - they'll all behave similarly. High priced alloys really won't buy you much, if anything. Save your money for go-faster parts.
 
nwpadmax said:
Resistance to bend and flex is the big thing.

Funny thing is, most people don't realize that all of the steel alloys have virtually the same elastic modulus, irrespective of alloy or heat treat condition. You can make a coat hanger out of 1020 or 4340 or 300M, and it'll still flex in your hand much the same.

Now if you're talking about actually pulling something apart, then alloy and hardness have everything to do with it. But in the case of traction bars, it's almost always about flexure, so choose any of the alloys - they'll all behave similarly. High priced alloys really won't buy you much, if anything. Save your money for go-faster parts.
Click to expand...

I must have inhaled to many welding fumes, do you think the tube that I have chose will be sufficient?
 
Correct. Depends on length.

1.5" x .125 wall......marginal. If you trussed them or made triangulated ones with 2 of those, you'd be good. One, by itself, is a bit light IMHO but again the length is critical.

Mine are 78" long 2" x 2", 1/4" wall square tubing. Some people say they flex but it's not obvious on video. I am changing the design altogether now that we can locally run rigid suspension, but my original plan was to run 2" x 3" x 3/16" tubing to get more stiffness but save some weight. But again my bars are quite long and therefore need to be real stiff.

Going too light on trac bars is nothing but trouble. Better to be good and rigid and a bit heavy, than to be too flexy.
 
You must log in or register to reply here.
Back
Top