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-   -   seam welding an FC (https://www.rx7club.com/race-car-tech-103/seam-welding-fc-231918/)

RussTypeS 10-13-03 09:48 AM

seam welding an FC
 
anyone have experience with this? im trying to figure out whats worth welding and whats not. obviously the shock towers to the fender well and the fender well to the frame. im also thinking about the cross brace behind the seats. the front and rear subframes seem like they could use extra stiffnes as well. would it be worthiwhile to do anything else?

sorry if this has been covered before, search is broke :mad: ...

and is there a trick to removing the rear axles? one of mine is stuck on really good. a puller+hammer+wd40 is doing nothing...

M's 10-15-03 07:57 PM

i'm not too much help but i know that the rear shock tower is probaby the weakest part of the car. So go nuts there and remember to tack along the car before you lay a bead down so you don't tweak the chasis

ForsakenRX7 10-19-03 02:16 PM

In Japan a lot of the tuner there will rivet AND seam weld their cars for extra rigidness. You see this a lot on time attack cars there. I would say any body seam you can find that would seem relevant to you in your head...weld it.

Lazy-Rx7 10-19-03 03:13 PM

i was wondering what type of welding you would do for seam welding?

mig? tig? stick?

if stick, what type of rods?

also would you just do a single pass or multiple passes depending on thickness?

RussTypeS 10-19-03 09:27 PM

im doing mig. i think alot of the places im going to weld would be too thin for stick. besides that i dont have a stick welder. ill let you know the wire size when i figure that out.

im going to do single pass. about 1" sections about 1" apart, alternating from end to end of the seam to keep the heat down. thinking about just doing the places between the spot welds from the factory. ill do both sides of the seam where i can.

what good would rivits do? welds are much much stronger. not sure what the point would be?

Re-Speed.com 10-20-03 12:42 PM

Russ, I dug up a shot of the last shell I prepped. The welds are 1 inch long with a few inches between them. I got .040 wire loaded in my mig - I never change it - seems to work fine.

-billy

Re-Speed.com 10-20-03 01:07 PM

Here is the first gen I am working on.

-billy

RussTypeS 10-20-03 04:07 PM

Hey man thanks for the pics.

i looked at a few cars at petit over the weekend. some were like that, some where a bit closer. i still havent decided what seams to do and what not to do but im thinkin about pretty much everything now.

when u wanna pick up those other motors? stop by sometime after work if you get a chance, the car is stripped now...

Re-Speed.com 10-20-03 06:06 PM

Maybe this week on the engines - things got crazy before Petite.

I got a couple of cheap engine stands from northern and made a rotisserie for the first gen. Make things so easy. I can rotate the chassis where I need it to fab and weld. You can see in the pic I mounted a bar across the bumper mounts and then to the stand.


-billy

RussTypeS 10-21-03 09:21 AM

damn that rotisserie is sweet. not sure an FC would fit that well tho. the other thing i would be concerned about is stressing the chassis while your welding. your holding the car up by part of the car that was not designed to hold any weight. i doubt its a big deal, but might be something to keep in mind.

Travis R 10-21-03 09:21 AM

I am partial to tig welding just because it has such clean results. But they are kind of expensive, whereas you can buy a used mig for much less.
I think it's called stitch welding, where you do a bead then leave a space before the next bead. I think WRC teams use this method. The metal is weakest right outside the weld. So if you do the seam with one continuous bead, and it starts to tear/break for some reason, then it will continue all the way down until your piece are no longer connected. With the stitch method, it should only tear through one stitch, and stop at the next one.
You also add less weight to the car by using less filler. It may only be a thin piece of wire... but over the course of the whole chassis, it'll add up.
I plan on doing my chassis at the same time I do my cage. Hopefully that will be before the end of the year. I get my tubing bender next weekend. :D
bwaits, thanks for the idea on the chassis rotisserie using engine stands. I think I might try that.

Re-Speed.com 10-21-03 11:11 AM

Would not worry about the stress between the two points. When the car is striped it is light. I can pick up either end of the car and move it around.


-billy

TrentO 11-01-03 02:16 PM

Thanks for posting the seam welding pictures. I'm getting ready to seam weld my Turbo II race car when she comes out of the acid tank. Your pictures make me more confident about my plans for seam welding the tub. I'm hoping to keep the car under 2000 lbs and put down about 320 RWHP so it should be entertaining.


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