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Discussion Starter · #1 ·
this may be a crazy question but can you mix moly and mild steel
on the same chassis, like i have a back half car that is mild steel
and now i want to clip the front with moly tube, is this possible and is it legal to race?:confused:
 

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Yes you can mix moly and mild. It is actually very common to do.:D
 

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.

Also very common by crooked chassis shops!!! Ask me how I know?? It's legal, cert will go down to the mild steel class.

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Discussion Starter · #4 ·
yeah, it's a unibody car. 74 nova. what about in the cage area
could i do the halo and down tubes moly to. the rest is mild steel
all 12pts of it.
 

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You can do it, but the fastest it will cert is 25.4 at 7.50. That is good enough for probably 95% folks out there like me anyhoo :p
 

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Youll be much happier with the end result of you stay away from the "halo" design. Use a single tube from the main hoop forward, and down the a-pillar. Then one across the top of the windshield. The halo design doesnt allow you to tuck the cage in tight to the body of the car, and isnt as strong IMO(yes, its an OPINION, i know).
Kyle
 

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Discussion Starter · #7 ·
i was goin to remove the halo this winter and do what you just told me.
i don't plan on going faster than 7.50's
it's mostly a street car.
i wanted to do a street strut front clip with moly tube.
 

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like others have stated, you can mix mild with 4130. one problem that you may run into that most wont even recognize is mild steel has a tendency to undercut when TIG welded. so, the recommended practice when mixing the two alloys is to MIG the two together as opposed to TIGging them. keep in mind though, now you are subject to the mild steel rules which is 7.50 i do believe.
 

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NHRA doesn't alow mig welding of any 4130 even to MS, IIRC. Any part involving 4130 requires a tig weld. If undercut is your problem slow it down, pull some amps and go to a bigger rod and just fill more in.
 

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like others have stated, you can mix mild with 4130. one problem that you may run into that most wont even recognize is mild steel has a tendency to undercut when TIG welded. so, the recommended practice when mixing the two alloys is to MIG the two together as opposed to TIGging them. keep in mind though, now you are subject to the mild steel rules which is 7.50 i do believe.
I have welded plenty of mild with no under cutting problems.Maybe you are not cleaning you weld joints enough?To much heat?Not enough filler?It takes more heat to burn through mill scale than it does to melt the base material.
 

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like i said, most arent going to notice the issue. i go to the lincoln invite only welding seminar every year, have been aerospace certified for 6 years for everything up to and including titanium and inconel down to .015" thin and i assure you, it is not a "me" problem with the undercut. we dont do any mild steel here at my shop. im just simply pointing out what is correct metalurgy.
 

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Where do you work and where did you get cert'd? Have always wanted to look into this but didn't know who to ask or where to start.

And lincoln sucks. ;)
 

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im not going to get into the red versus blue debate. i got involved with lincoln through my connections with NHRA about 8 years ago and they have been a big help as far as cutomer support, technical advise etc... miller is so involved with the backwards ass nascar guys, i tried to work with them on a few things and they wanted nothing to do with us. so, i went with the red guys. im partial to lincoln because of the help they have given my business, but miller makes an excellent product as well and would hard pressed to make a decision between either if i was starting from scratch.

as far as certifying goes, you need to contact your local AWS representative. we have one here in indy and i had to get certified to do some aircraft "schtuff" we were doing a while back, and i have just kept up with the cert ever since. some colleges offer it in addition to there schooling or sometimes you can do the hands on test yourself in yout facility and send off your coupons to get tested. dont quote me on that though, i have only "heard" of that being the case.
 
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