Seam welding virtues

This is probably a pretty newbie question, but what are the advantages of having all of the body and chassis seams welded instead of using seam sealer? I occasionally hear people talking about having their entire car seam welded, but never an elaboration as to why.

Also, if I get this done on my Ghia Coupe project how many hours would it normally take a pro welder to do the pan and body? My welding skills suck big sweaty camel balls, so I'd need to farm it out.

Thanks!

[Humble]

Seam welding isn't a solid weld on all the seams but a 3-4 inch weld then a 3-4 inch gap then a another 3-4 inch weld and so on. It's also called stitch welding for that reason. It's used on unibody cars (pretty much all new cars) to radically stiffen the whole chassis. Normally when cars are built there are numerous pinch welds the assembly robots make to hold the car together but they still flex a little bit. Seam welds reinforce the body where all the different panels meet to keep them from flexing.

The process is very messy though if you want to go through with it and I've seen it and done it form a club racer car to a US touring car. First you have to strip the car, all the way down until nothing else comes off. Next, the easiest, fastest, cleanest and most expensive way is to acid dip the chassis but don't have it primered so when it comes back you can get right to work. Or, you can strip it the hard way, by hand, using chemicals and power tools it makes a mess you'll be cleaning up for a long time. Having done both its acid dip every time now. Once the chassis is down to bare metal you can start the stitch welding process which can be 1-2 days of welding and it really helps things if the car is on a rotisserie.

Now the bad news, since the aircooled cars are body on pan and not a true unibody I'm not sure how much a bug or ghia would benefit from this pocess. I'm sure there would be a difference but adding a rollcage would probably be a better and cheaper option. If you do the stripping process yourself and work on it 7 days a week for 5 hours a day you can probably get it done in 10-14 days doing a thorough job and it'll cost a 175-250 for wire wheels, a torch to get the seam sealer out, and a good pick. Then it's whatever the welder bills you. An acid bath will set you back 1500-2000 depending on the shop, again it's expensive, fast, and clean. An in between option would be getting the car media blasted, cheaper that acid bath and someone esels mess.

[Bug@5speed(US)]

VWdevotee,

From a seat of your pants perspective, I can tell you that when we lifted the chassis around, it was substantially stiffer then when it went in...

I had it done to my chassis, but still awaiting on a new fuel line as there was an issue with placement..

Take a look toward the bottom..
Alex

[Bug@5speed(US)]

OK forgot the link:
http://www.germanlook.net/forums/sho...?t=9094&page=2

I am happy with my decision, was not going to do it but went for broke..

Enjoy
Alex

Thanks to both of you. Alex, can I ask how many hours you got billed for for the shop to weld up the seams? That is one sexy looking pan.

[Bug@5speed(US)]

VWdevotee,

Sorry for the delay.. I will pm info..
Alex