Seam welding
 

I know on most all unibody cars seam welding helps a lot. But a few have told me that it's a waste of time on an FB.

If anyone has any info on seam welding the FB (Pros and cons) I would like to hear it.

Thanks in advance.

Can't believe nobody has any info on seam welding.

I agree it does help, I can't imagine why it wouldn't help the FB. Seam welding is a major stiffening modification and the FB is just as unibody as any other rx7.

BigAl...

^^ I don't see how it would be a waste of time in a fb... unless secretly the fb is the stiffest rx7 ever lol

im actually getting ready to do this in my fc. from my experience you should get much better response and feel of the car.

I have two rally shells, both of which have some level of seam welding on them.
I have no doubt that this has helped them to survive as long as they have.
If I was to build or have built a unibody shell for any serious motorsport activity, there is no question that I would seam weld to help improve chasis stffness and to promote longevity.

Anyone have any info on best spacing, size of weld, etc....

A friend of mine with a race shop does seam welding but he mainly does it on acid dipped frames that are ready to go. It dramatically helps strengthen the chassis especially with a race cage.

1" at 1" spacing is the norm.

Ok. I figured as much. The only thing that held me back was once I did it. The car will not be SCCA IT legal (resale value)

I did a kind of seam weld on my S14 front end when I tubbed the front end. I'm not sure how thin the sheet metal is on the FB but on the S14 it was very very thin and easy to blow through (ask me how I know). I ended up doing spot/tach welds on the seems every inch and it worked out much better than trying to run a 1" stitch weld. If the sheet metal is thicker than the 22 gauge on the S14 and you are careful 1" stitches would be ideal.

Yeah, it is real easy to blow through, but it can be done! I think a big problem is getting the crud that is between the seams so the welds arent all contaminated, which is also related to blowing through.

Started seam welding on my FC drift project.... 1" welds at about 1" spacing. Using stargon and a miller welder set to the 2nd temp setting.


Attachment 673017

It may be to late. But make sure the car is setting flat, on level ground. So there is no twist in the frame when welding.

its necessary the faster u want to go. a FB benefits from it the most. but lets be real here, theyre japanese cars made for a profit. if you want to make it faster u need to start with the welds and metal work. its that simple. the hardcore race shops do it, so why not?

per my friend, builder of rally cars for a few decades.

As for what to weld... I love it that Ford Motorsport said in all their books from RWD Escorts onward---including Sierra, on page 1 paragraph one: Shell Preparation. They stresed that this make for a stronger shell and for us privateers Goes on to say



They mean it when they say EVERY and should stress they mean to do this AFTER the cage is welded in... cars to twist and tweak if you weld like a maniac in one area..I have warped a sand truck trailer body by 4" welding too long in one area..long ass trailer made of pretty thich plate and it pulled up 4" at one end...Fortunately the boss was sharper than me and by time he was done it had pulled back town to flat..
So move around a lot.


As for should you get so thorough---local rallyguy in his first event too a wrong slot at a Y that some fool had seeingly intentionally driven thru the tapes and met a Subie guy and kind of banged into the Subie guy---who had realised they had gone wrong and turned around and was heading back..
VW Rabbit , gently kiss and the car is tweaked seriously...if the car was stronger, the one corner would be smooshed, but the other parts straighter and an easier fix..

I guess it depends on how long you want to keep the shell--and the cage you spent time and effort installing.[/quote]