I'm curious to hear some opinions on the effectiveness of seam welding a unibody chassis.

Does anybody here have experience with this? Does it make a signifacant difference in chassis stiffness? Would it be worth doing if, say, you knew an experienced welder and were going to have some "downtime" for your car?

 

Possible future project? I'd definately do it if it made a noticeable increase in chassis stiffness. What about sub-frame connectors as another method to increase stiffness?

 

How ironic.

I was just talking about this with a friend.

Acid dip the chassis, get it on a rotisserie, then seam weld it.

Do it if you have the means.

 

AND if it is legal in the class(es) you compete in.

 

Subframe connectors may also be worth looking into, however I like the subtlety (in concept) of the seam welding approach.

I wonder what's necessary to seam weld. I figure the most crucial areas will be around the wheel wells, floorpan and roof. Would it be possible to get results without using a rotisserie? Could it be done on a lift with the engine and interior removed?

I'd love to hear some more opinions on this subject.

 

Not practical. At all. Period. End of story.

This is for race cars in appropriate race classes.

Warren

 

Im pretty sure you seam weld the chassis so you can cut away most of the
innards and retain some rigidity

 

You need to make sure a welder who knows what he is doing is working on the car. Somebody applying to much heat in the process could easily warp whatever parts you want welded.

 

Thanks. This is the kind of input I'm looking for.

Could you please elaborate on why it is impractical for street cars? Since my car is first and foremost my daily transportation it is important to me to not ruin its practicality.

Is it impractical mainly due to cost? Are there other downsides to it? If I were to do it to mine I would not be removing any material. Is there a safety issue with strengthening the chassis in this way (i.e. reduced effectiveness of crush zones)?

This is really just a notion I've been entertaining. That's why I'm looking for input from people with some kind of experience with it. If it is a bad idea, of course I won't do it.

 

Seam welding is big with the race 5.0 crowd. Anytime you get over 300whp in a 5 liter twist becomes a serious problem. My previous fox body (a '92 GT) had a fully seam welded rear subrame in addition to reinforced torque boxes and subframe connectors. After all these mods were completed the car felt German, plain and simple. The difference was astounding, my current stang has sub connectors but thats it, I actually plan on seam welding the rear tub this coming winter.

 

So was this a Street/Strip car?

How much of a PITA was it? Did you notice anything about it that would make it an unreasonable mod for a street-driven car?

 

Yes, it was a street car with a road race suspension, bear brakes, 17's w/Hoosiers the works. The car stuck like glue EVERYWHERE. Seam welding the cheap, spot welded chassis in a 79-93 Fox body makes sense, since these cars were not the tightest of unibody structures to begin with and had huge torque to contend with from Windosr V8's.

But I don't see how seam welding a DC2 is possible?

 

seam welding makes a difference in track cars when subjected to twisting that they go thru...
it is a major PITA to do...i also see alot of cars using rivets which they said is easier to do but still a PITA and you need hundreds of them
As for stangs I know 3 million people with them
a few didnt go thru the usual subframe and chassis mods
cracked windshields the usual twisted body and never shutting right doors
there is a very twisted convertible I know of complete with collapsed torque boxes the roof and doors dont line up
looks horrible

 

How much of a difference did just the subframe connectors make on your car? Any downsides to subframe connectors?