mig welding drag car chassis opinions

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hi all!my son is in the process of building a back half-ed drag car, and is building the chassis from scratch. using a hobart 210 (240v) with 75/25% mix .035 wire. frame tubing is 2x4 .120 wall. round tube is .120 wall. would like some opinions, and guidance on the welds from the experts. no cage yet on order. will be 12pt. and still plan to gusset the seams where the chassis comes together, but dont want a failure either since this will also be a street car making good power. it all layed pretty flat. Last edited by vette76; 07-08-2014 at 07:33 PM.
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Reply:(as for the last 2, i think i need to reburn the top horizontal weld hotter? and the extra bulky part on the last pic is because i was afraid i undercut that spot too much)
Reply:I personally am not a fan of downhill mig welding.
Reply:Downhill mig is fine for thinner metal .120 is roughly 1/8 thick. Any thicker than that I'd suggest up hill mig, overall the welds look good to me.  There a lot better then most of the welds you see on factory trailers etc..Last edited by That Guy There; 07-08-2014 at 08:12 PM.
Reply:funny you said that, i just saw the thread about the "NEW" trailer someone bought with pics. haha. i am pretty confident i got decent penetration there. the welds are pretty flat, and i moved pretty slow to try to make up for it. you can see in some pics where i tacked it, and stopped before and started after the tack to now load it up with material.  i plan to add plate over the seams for extra security. dosent look the prettiest, but i'm not a professional. flat welds are a good sign of penetration and... shouldnt have to worry about strength loss, as long as they are not convex correct?Last edited by vette76; 07-08-2014 at 08:37 PM.
Reply:A flat weld isn't an indicator of a good welds a person can lay a flat weld by going fast and hot for with mig. To gauge penetration weld a coupon of similar thickness etch it then use a up light (I think)  you should see the weld nugget clearly. Although I think you penetration is just fine on those welds
Reply:Originally Posted by M J MauerWhat class is the car going to run? Must be able to pass inspection.