Anybody stitch welded their car?
 

I saw these Japs in BMI stitch welding an AE86 to improve body rigidity. But they have a special tool that compresses the body sheet metal and lays a nice tack weld. I think this is do-able with a MIG and probly a vice grip. any thoughts?

Re: Anybody stitch welded their car?
 

Many people have seam welded there car. It's a long process because you don't want to overheat your panels and warp them. Being that you car is only spot welded together (trust me, RHD Conversion makes you learn this!!) some guys lay 2" Sticthes every 4-6" on the 2 overlapping panels.

The unit you are talking about uses a High-Current electrical weld that clamps the 2 panels together a fuses them by using this very locallize current to create the heat. Have you efvery seen a New Gas tank that is un-coated, exactly how they weld the top and bottom portion together.

Re: Anybody stitch welded their car?
 

It's a common practice to do when you are building a car for motorsports. The factory spotwelds make a flimsy unit-body vehicle even more flimsy. Suspension pickup points move all over hell. In most instances( ie daily driver/lo-po), I don't think it's worth stripping the car and welding all the seams. I ,however, haven't done such to a car yet so, I can't speak from experience how big of a improvement it makes.

Re: Anybody stitch welded their car?
 

Yeah I am planning on weekend road racing my car. It is a convertible that's why i'm doing every possible mod to stiffen the chassis.

Re: Anybody stitch welded their car?
 

Have you looked into cages/bars yet? I know it might be a bit cramped in an MR2 Spyder, but those definately stiffen everything up like a 3rd grader during sex-ed.

BTW, you car = teh sex

Re: Anybody stitch welded their car?
 

Yeah that's on my list too including breast plates and some more lower chassis brace. Thanks

Re: Anybody stitch welded their car?
 

Is that actual Wheel to Wheel road racing or HPDE/Open Tracking? The cage and strut tower brace will help. I am not familar with how the front suspension attaches to the body to say a g-brace will work.

On a slightly different topic, look for some more race oriented front pads. Stock pads will suck after a few hard applications.

Re: Anybody stitch welded their car?
 

open track. yeah that was also the same suggestion of a fellow Mr2 driver. He said stock brakes on mr2 are very good dont fade, for security an aftermarket pad will do.

Re: Anybody stitch welded their car?
 

the hb we built for rally took just shy of 20 hrs to fully seam weld, fab strut bars/braces, clean and prep for paint. made a huge difference. Just remember to wear a resperator, and cleann all the welds before you start

Re: Anybody stitch welded their car?
 

uibodys are actually quite a good design, when done right. pound for pound a unibody car is stiffer than a frame+body car

Beau

Re: Anybody stitch welded their car?
 

True, I am making a generalization and generalizations are bad (sometimes ;)). It also (I assume) comes down to body configuration ie: fwd, rwd, midengined ,length of wheelbase, width of track and how much overhang the front and rear the vehicle in question has. Also,depending on where the engine/trans/heater/dash/occupant is in relation to the suspension points it may help or hinder what the factory can add for body bracing. I'm sure the engineers that do that math stuff have a list of maximums that they expect a car to see routinely and have a design up to those limits. Throw some stickier tires and bigger brakes and more power so on and so on,the car will twist more just because of the added forces.

Both unit body and body on frame cars can be made stiff but like all things, it's a compromise.

I still think the original reason for the unit body was just lighter weight not increased rigidity. Body on Frame would (generally) have superior beaming stiffness. Torsional...it's a tossup.

Re: Anybody stitch welded their car?
 

I stitched my drag car, and it will also get a full cage. Anything you can do to help keep your car stiff will be worth it. Flexing of any sort can break factory felds and stress crack your sheetmetal. Not to mention that the power being used to twist your car isn't making it to your tires!

Re: Anybody stitch welded their car?
 

isnt it easyer just to add spot welds closer to each other? :l

Re: Anybody stitch welded their car?
 

Easier, but not as effective. Also, don't think more welding is better. Don't weld more than 1.5-2" in a row, then jump 1.5-2" and weld some more. You don't want the entire seam welded or it will create a stress point and will crack under loads. Just a FYI

Re: Anybody stitch welded their car?
 

The spot (arc) welder you talk about doesn't really clamp that hard. FYI, it's a sub-$200 tool, nothing speshul.

One of VW Richard's (local guy, I used to turn wrenches with him at an old job) friends has an old 1G Scirroco. He braced all the suspension points with RHS bars, then drilled holes between the factory spotwelds and filled them up with a MIG. Close enough for rocket science.