welding all seams in a car...

[absolom]

for stiffness...

anybody done this?

and is this the right subforum to discuss it?

basically, the idea is to weld all the factory seams that are basically just put together with spotwelds for strength right?

we're thinking about doing this on our fastback that we're currently building

[chicane67]

Its common practice on unitized chassis... and we used to do it to all the Miata and Geo Storm chassis for their respective "Challenge Series."

It makes a noticable difference.

[ProdigyCustoms]

Its common practice on unitized chassis... and we used to do it to all the Miata and Geo Storm chassis for their respective "Challenge Series."

It makes a noticable difference.

Yeah, what he said. And also, you won't have unsightly cracks in you nice paint job later either!

[absolom]

Yeah, what he said. And also, you won't have unsightly cracks in you nice paint job later either!

anybody ever done this on a mustang or have pics of it done to a mustang?

we're through sandblasting in about an hour, and it's on the rotisserie right now

it would be the perfect time to seam weld all the joints

front heidts suspension goes in enxt weed

:seizure:

[chicane67]

Yeah... have done Mustangs as well.

Not so much of full seam welding on an early model/first gen... but the front sheet metal/upper shock pockets would be done and some added sheet bracing to the K member and suspension pick-up points.

The late 80's/early 90's fox got nearly the same treatment... except for when the rules said we couldn't do it.

For a street chassis... be careful on how much heat you localize into any section that you are welding. I wouldnt do more than about 8-10" at a time without some cooling in between stitches. And remember... there is probably still some seal sealer in the panel flange/gap... so it can/will screw with you while welding... or even catch fire. Reminent sand from blasting will also give play hell with welding too.

[gkring]

The books I have read recommend welding 1 to 2 inch stitch welds and not to fully seam weld. Sounds easier and faster, would there be a reason to not fully weld a car besides the time in actual welding and cool down between sections? I would think having a solid car to start with and strategically placed reinforcements would give you most of the benefits, and fully seam welding could be 90% more work to get 10% more benefits? Now would be the time to do it, not really something you can go back later and add!

[kmcanally]

My mustang coupe was seam welded during chassis restoration. No pics though but rear subframe, front subframe, shock towers, firewall to inner fender, strut rod boxes to subframe. The Boss 302 chassis modification book has details on this http://www.trophymustang.com/boss-chassis-modifications-p-6214.html

[absolom]

The books I have read recommend welding 1 to 2 inch stitch welds and not to fully seam weld. Sounds easier and faster, would there be a reason to not fully weld a car besides the time in actual welding and cool down between sections? I would think having a solid car to start with and strategically placed reinforcements would give you most of the benefits, and fully seam welding could be 90% more work to get 10% more benefits? Now would be the time to do it, not really something you can go back later and add!

yeah, we'd be making our own subframes and stitch welding the major body seams if we do this

[absolom]

My mustang coupe was seam welded during chassis restoration. No pics though but rear subframe, front subframe, shock towers, firewall to inner fender, strut rod boxes to subframe. The Boss 302 chassis modification book has details on this http://www.trophymustang.com/boss-chassis-modifications-p-6214.html

we're using a martz chassis 4 link and heidts front suspension, so we'll mostly be doing stuff to the firewall, frame rails, subframes, etc etc

[ATAK, Inc.]

The books I have read recommend welding 1 to 2 inch stitch welds and not to fully seam weld. Sounds easier and faster, would there be a reason to not fully weld a car besides the time in actual welding and cool down between sections? I would think having a solid car to start with and strategically placed reinforcements would give you most of the benefits, and fully seam welding could be 90% more work to get 10% more benefits? Now would be the time to do it, not really something you can go back later and add!

The way to weld without the worry of causing any distortion is to start out with a work area of two seams of 24" each for arguement sake. lay out 8" marks. Produce a 1" weld at each mark, by the time you did the 6 welds you are ready to go back to the first weld and do another 1". Repeat until the seam is welded all the way. This will keep the HAZ (heat affected zone) down to a minimum. As far as not welding the whole seam, why not, you are there, go the extra mile, that way you are not going to have filler in between the welds and once ground down a nice uniform finish. Even if you are using GMAW (inert gas as a shield), clean the area with a brush, in welding, cleanliness is everything.

[CptKlutz]

We stitch weld our track Mustangs over here. About 1" weld then 2" clear then ....
Is it just me or wouldn't you warn a bit about ride quality changing for a street car? It seriously does what it's meant to: take out any flex AND dampening in the chassis.

[jackfrost]

would this help on a full frame car ?

[KWIKND]

The books I have read recommend welding 1 to 2 inch stitch welds and not to fully seam weld. Sounds easier and faster, would there be a reason to not fully weld a car besides the time in actual welding and cool down between sections? I would think having a solid car to start with and strategically placed reinforcements would give you most of the benefits, and fully seam welding could be 90% more work to get 10% more benefits? Now would be the time to do it, not really something you can go back later and add!

The thinking for stitching vs. continuous weld is that if a crack does form somewhere in a continuous weld it will travel through the entire weld. In a stitch weld only the one stitch will crack.
Dan