Too Anal? Fed tubing question

If I'm buildin' an fed, should I be concerned about 1020 and 1018 tubing designations? I did find out it means machinability, but how does that affect bending and mig welding the tubes and/or flexibility? D.o.m. is what I want to use.

 

Are you gonna pass NHRA specs with mig welded components?

 

Chrome moly can only be tig welded. D.O.M can be mig welded. D.O.M is good enuff for nascar so it should be good enuff for fed sportsman stuff.

 

1020 has slightly higher carbon content, but it's really nothing between the two. 1010 vs 1020 is a little different story. Shouldn't be any problem with fabrication, especially in the thickness you'll need to be legal.

 

Be careful when using mild steel tubing, even though its listed as .120 wall ,in realality its .114 wall and not legal, Thats why mild steel sportsman cars are .134 wall.

 

Thanks guys. Is .120 wall the only size like that or do I take a mic. with me to the steel distributer? C'mon Racecar,reassure me.

 

Yes you can MIG weld chrome moly.

Some sanctioning bodies require TIG in their rules though.

 

All tubing has a + or - tolerance in the wall thickness. The real problem lies in bending it for roll bars. As the tubing is bent it stretches or elongates thinning the wall thickness. This is why thicker than required tubing is often used for, at least, the rollbars.

 

Mild steel tubing is legal the rules lump all mild steel tubing together dom is a lot more consistent and stronger than erw 1020 dom flexes nicely in a fed chassis
sorry i had cap lock on

 

Most mild steel tubing will be thinner than the nominal wall thickness in some (if not all) places (especially ERW). As stated most .120 nominal thickness tubing comes in at around .114 and .118 is required and that is why most door car chassis kits are bent out of .134 wall.
DOM is usually a lot closer to the spec because it it made the same way as 4130 cm but it is nearly as expensive as 4130 when you account for the fact that you as buying more material due the the extra wall thickness required.

Roo

 

Consider me reassured. Time to order some tubing!!!!!

 

Sorry Tman tig only on the chrome moly, dont want any pesky toe weld crack and fail and DIE situations.

 

first off it's a Z, second there is a difference between saying something can't be done and what happens if it's done wrong. You are WRONG. Chrome Moly can be MIG welded, period. If your skills aren't up to it that's not my fault.

And really fill out your profile and do an intro.

 

Forgot to post my quals and been seeing your all knowing posts for some time. I don't think I need to intro duce myself to someone like yourself that thinks you can weld chrome moly tubing safely with MIG. Good Day to you sir..............

 

well seeing as there are everyone from aircraft manufacturers using MIG on 4130 for their airframes, baja racers, motorcycle manufacturers on their frames, and on and on. You just really don't know. Getting and attitude about it makes it funny. Hotroddon was even nice enough to post the technical details for some of it.

 

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I am right in the middle on this one as although as stated 4130 can be successfully MIG welded it is not a totally straightforward process as seen in the guidelines posted. When OEM style manufacturers MIG 4130 they have a bunch of engineering and hopefully a lot of testing of the final weldment to guide them. Doing it in a home shop environment is not the same, especially when using the thin wall tube that is the norm for a 4130 dragster frame. I see enough sub standard MIG welds on thick mild steel frames to be very worried about someone trying to stick 4130 together with anything other than a TIG welder.
Of course if you can't weld properly with a MIG you probably won't do much better with a TIG but at least the process happens a little slower and for my mind is a little easier to control.
Anyway the original question was re the spec of the mild steel so we are basically de-railing the thread and have no idea of how duecegasser plans to stick his frame together.

Roo

 

4130 improperly welded causes accidents 2 guys I know are handicapped because of it their cages snapped at the welds and ended up with broken backs and this were pro-built
use mild steel and be safe

 

When in doubt.........fab it up yourself...tack it together ........and have it welded by a proven qualified welder..........Littleman

 

After having manufactured short track oval racing chassis for 15 years for Howe Racing Enterprises (produced over 3000 chassis during that time) I can assure you that Chrome Moly CAN be sucessfully welded with Mig. It might pay for some here to do some research before posting definitive statements no matter what the subject. "old wives tales" do nothing to further the education of the many new guys that participate here.

Frank

 

Check your rule book CLOSELY. You can be certain the Chassis Inspector WILL be anal - it's his job to be!!!

 

That should be the first consideration when building any race car chassis for any style of racing. Unless it is a display only cackle fest style car that will never make a pass down a strip it's time to research the rule book and follow the guidelines set down there.

Littleman's suggestion of tacking it together and then taking it to someone who can weld it right is a great one. I built my T bucket by tacking pieces together and then taking them to a friend who was a highly skilled welder to have him to the finish welding on.

 

Obviously not really "pro built" if the cages snapped at the welds. A poorly welded mild steel car will break too and as I noted earlier I see a lot of them in my business. Race cars (or street rods for that matter) are not the place to practice your welding. I am with Littleman on this one too--if you are not a weldor find someone who is, and not just the guy down the street that has a 110 flux core rig.
As for the TIG vs MIG argument, if you use 4130 and want to run at NHRA events listen to HemiRambler, it needs to be TIG welded as per their rule book.

Roo

 

That there is good advice. Have done it for more than a few people. You don't pay for the fab, which tends to be the time consuming part, and you get quality welds. You do have to be able to fit things up well though. And on the 1018 vs 1020, I'd use either but would prefer 1020 if both were availiable. 1010-1015 is furniture tube.

 

From my 2008 NHRA rulebook: 4:11 Roll Cage

"All 4130 chromoly tube welding must be done by approved TIG helicarc process; mild steel tube welding must be approved MIG wire feed or TIG heliarc process."

So it really doesn't matter if there are other ways to weld, if you want to pass NHRA tech you must adhere to the above processes.

 

+1 Moly circle track chassis' are mig-ed all day, everyday.

The issue as it applies to this discussion is that NHRA specifies tig only for moly.

 

If you build a FED what`s beter to drive 180"or a 200"

 

Theoretically the longer wheelbase should make the car more stable but the design of the frame, engine placement etc all come into play.

Roo

 

Come on Alex,,I know you suffer from A.D.D. but what about the coupe? HRP