Thread: Seam Welding
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Old 06-16-2009, 08:11 AM   #3
Scooby Newbie
Member#: 102091
Join Date: Dec 2005
Location: North, Ontario, Canada
1994 1.8l Impreza L
Open Class Build w/110hp


Here is my oppinion:

Originally Posted by goalieboy1 View Post
"seam welding" what exactly is it
Seam welding is also referred to as 'stich welding'. It is a bunch of small stitches, or welds laid across the seams of the unibody. Because welding changes the structural properties of metal, small beads are laid at specific intervals. This HELPS to prevent warping of the shell, as two sheets of steel when heated and cooled (during welding) want to change shape slightly. Also, the OEM spot welds are doing a fine job, seam welding just helps out to add a bit more strength and rigidity.

Originally Posted by goalieboy1 View Post
pros and cons
Stronger shell
Safer shell
Localized crash damage
Easier to 'pull' crash damage (not to fix though)
Awesome way to learn to weld
The cool guys do it

It's an obscene amount of work
Lots more work to replace body panels
You'll get told by 1000's of people that you don't NEED to do it
Lots more work to replace body panels
It's an obscene amount of work

^^^both of those lists can be expanded upon

Originally Posted by goalieboy1 View Post
is there any special technique to doing it or can it be done by mig
I only know of one person who has ever done it with a TIG welder, the rest have used MIG.

There are as many techniques as there are welders (from what I gather). I listened to my cage builder and a local car builder/racer. You can read about what I did in my thread. Some people push the bead, some pull, some do what I did for the majority of my shell.

Spacing the stitches is also something you'll hear allot about if you ask allot of people. I chose 1 inch welds every 1.5 inches because that's what my cage builder suggested... I've heard everything from 0.5 inch welds every 2 inches up to nearly full beads across the seam.

The Truth:

You more than likely don't need to do it! There are more reasons NOT to do it than there are to do it. If you were building your 3rd car, you'd been placing high in your class consistently for a while, and your car was oozing horsepower, then seam welding would most likely be necessary.
I did it because I thought that the possibility of minimal gains was worth my time, for many (unique to me) reasons.
That being said, seam welding around your front strut towers is a VERY good idea!

EDIT: If you are NOT acid dipping the shell, budget 30 hours minimum to seam weld your car...
(don't acid dip your shell - you never get paint back where you need it)
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Last edited by urabus555; 06-16-2009 at 08:18 AM.
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