I have a 91 CRX I'm installing a S&W Roll bar 8-point. The front floor plates I decided to just use four 1/2" bolts and bolt those down, because they were in the corner and kind of annoying to weld (I'm not a pro so it's hard). It's all legal, because the NHRA rules say I can have the floor plates bolted down with one 6x6 1/8" plate on top and one on the bottom and at least 3/8" bolts.

Anyway I'm having trouble with welding the rear floor plates to the floor. I'm welding them to the floor right behind the strut towers. What I didn't realize is that the floor right there is like sheet metal...I found out the hard way by blowing a couple holes I tried beveling the edge of the plate and I seemed to get it down but there is a very fine line between welding and just blowing through. I have a cheap harbor freight welder, so that isn't much help I tried it on lower settings and the thin metal would be fine, but the 1/8" plate wouldn't get good penetration. I tried welding the edge of the plate and just barely touching the thin metal, it worked for a while. I was thinking is this even a good plate to weld it to, if the floor is that thin? Would it be better to weld it to the wheel well (I could bolt it down that way also)? Any help/advice is very much appreciated.

 

what if you do a pass rightbeside the plate on the floor on a lower setting. this should build up the floor and be easier to penetrate the plate. im not a cage builder but would assume that would be ok.

 

Yeah, I'll try that. The lowest setting is still pretty high so I have to still be careful. I was really thinking about it, and I looked it up and where I have it now is the trunk pan (sheetmetal), and I don't think I really trust it as a support point. I might just move it to the strut tower or wheelwell because that is apart of the actual subframe and thicker. Does anybody see a problem with just bolting the plate to the wheelwell and have the bar go through where the speaker would go? I've seen it on bolt-in roll bars before, but they are usually not NHRA approved.

 

fwiw i had a safety21 6pt with halo in my crx and it bolted to the rear wheelwell through the speaker hole. you could also weld 12" long strip down the flat section beside the spare tirewell. this will reinforce the sheetmetal and carry the load over a much greater area. the whole car is pretty much just layers of sheet metal anyways.

 

Yeah okay. Was that safety21 roll bar NHRA approved?

 

no. i was just giving an example of how another cage was made. sorry

 

take your time, and do it in steps. i had to basically throw down 500 tack welds to get mine to weld with good penetration but not blow through, and the little gaps were a chore, thats for sure.

probably put out about 75 fires on the bottom of my car.

keep the compressor on and the air hose close by to put the undercoating out.

 

This

 

If you have the room you can also try pre-heating the thicker material with a small torch or something. The added heat will help you with the penetration. If you can avoid heating the sheet metal.

 

how clean do you have the metal? the cleaner the sheet-metal the easier it will be. The main advice I have is just take your time, sometimes with lower end welders that do not have many adjustments things like this are a little hard, but if you take your time you should be able to get it.

 

i used a huge miller that can burn through 3/8ths plate, and i was using .035 wire. it was a nightmare.

i shoulda used my 110v mig with .024 wire. haha would have been much easier.

 

How is this coming?

 

Any pictures???