seam welding Chassis
 

Seam welding chassis.

I always wonder if this type of thing is actually worth it for us normal people. It always sounds interesting to me, and there are all sorts of articles about legendary japanese tuners that go nuts on chassis and weld the ever living daylights out of them and how it makes it so much better.

But is it really worth it and how much would it actually cost? I doubt it would be cheap.

is this to make more sturdy? Any benefits to cornering?

I believe the general idea is to lessen chassis flex to make inputs sharper and allow the parts that are supposed to move be the only ones that do.

I assume it would stiffen the structure substantially, but it's not practical on a road car because you'd have to strip the shell down to bare metal along the seams in order to weld it, and then you'd need to paint the welded seams to prevent corrosion. How willing are you, or any sane person, to do that?

I will be the first to say RIP to you when you get in a wreck, if you use this on a street car.

Things like this change the crash characteristics of the car, to the point where portions of the roof may cave in and cut your head in half.

I'm not being a ****, I've seen it happen.

-alex

I once helped a friend build a street car that is seam welded.

Even with an entire 20+ person bodyshop at his disposal, we gave up after painting the chassis and left the insides of the car barren.

-alex

It might do good but it's not cost effective. On an ae86 or na miata? Probably notice but there are better ways to go faster.

Have seam welded a Civic racecar before. Not fun.

86s are more than stiff enough for street use. If it's a racecar, get a cage and call it a day.

+1 This is removing the crumple areas that would essentially save your life. I can see this on a dedicated track car but a DD is moronic to do this. Just someone selling untested unproven snake oil.

How can you see it on a dedicated track car but also think it's untested unproven snake oil on a daily driver?

I don't think it's a good idea for the reasons others brought up about the diminished crash protection but it seems like a completely reasonable way to stiffen the chassis.

Depends on your definition of reasonable... to seam weld it properly will take weeks of work. Unless you have a specific goal in mind (ie you've measured too much deflection in a given situation and want to eliminate it) and are going to measure the improvement it's simply not worth the effort IMO.

There's also a lot of other points of deflection before the chassis is the weak link, so unless you've replaced ALL the rubber bushings with bearings there's still something MUCH easier to do to improve feel and suspension precision.

Because dedicated race cars have full roll cages that meet official specifications, fixed back seats, and harnesses to restrain the drivers, so they don't rely on crumple zones to absorb impact. Daily drivers typically don't have any of that, so you're taking a integral part of the car's safety system and keeping it from being able to function.

I read it that he could see seam welding working on a track car but as unproven snake oil on a DD. That just didn't make sense to me.

I think it could be equally effective in both applicaitons but I agree with you. Obviously not advisable for a DD for all the reasons you (and others) described

If one were ONLY stiffening the chassis and not doing anything else with it, i.e. drive it on a public road, then yes, I would agree with your statement. But since OP is asking about a DD, then your statement is wrong for all the reasons already listed.

If one gets in a wreck with a seam welded chassis, the impact would easily overwhelm your stock seatbelt + airbag's ability to protect you. You would need to reengineer the entire safety system to compensate for much higher G-forces in an impact. Even a 15MPH impact can kill you.

Plus, the "unproven snake oil" part mostly revolves around the change in crash characteristics of the car. Plus, once you stiffen the car you change the natural harmonic frequency of the car, thus introducing the "unproven" part of the problem.

-alex