Kazama1986

My friends are all starting to stitch weld their body panels and what not. I am not sure if i wanna start. From what i understand that if the car were to ever be hit it would totaled due to the fact that the car wouldn't crumble correctly. I have a 92 coupe and it's got about 190,000 miles on it and it is pretty solid as is. The factory body seams seem to be in good shape. But if i were to stitch weld anything it be the strut towers and the door openings and maybe possibly reinforce the transmission tunnel. Or should i scrap that thought stitch weld everything or not even bother?

bribot

hope this isnt your daily driver. if your going to stitch weld at all you might as well do the whole thing. but i wouldnt do it if you drive it everyday

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pwr-adr

Why not? I see nothing but positives results with welding it up. I drive with solid motor mounts, I made myself, but I have no issues. If you can handle driving on coilovers, stich welding wouln't make a difference in feel.

g6civcx

Can someone explain why?

atutt

^Solid motor mounts are different from solid car...

I personally wouldn't do this to a DD. It's FAR to time consuming. Doing to half a car or a third of a car is a waste of time. If you're gonna do it, do the whole damn thing. Last time I did one it took me over 80 hours to do the whole frigging thing... Then I never ended up driving it....

Kazama1986

it's kinda of a dd. it has peak performance "solid" motor mounts and aluminum driveshaft so the power is delievered kinda "solid". but i see your points. its kinda just a point of taking my engine out again having to repaint the engine bay. i'm kinda lame in the fact that i like facotry baked on paint more than rattle can materials. also if i do stitch everything should i take a chance do the radiator core support aswell or not risk it.

dino6192

just doing part of the car will actually add more stress to the parts that are not stitch welded. if your going to do it, then do it. cant half ass that one!

drftem

hmmmm. i still dont understand why you suggest against this for a daily?

bribot

because the car wont crumple like its supposed to!! just think about it for a second... so you go hit someone, YOU take on the full impact of the wreck instead of the car... PLUS the person you hit is getting a harder impact also since your car has nowhere to crumple.

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project-D180

i think you should do it..i think it would have the car with better turnability

project-D180

how much stress can stitchin strut towers add to the rest of the body??

spoolandslide

i am starting a build from the ground up

i have decided to stitch weld the entire chassis, should i also put a roll cage in

how much of a change will that make?

GSXRJJordan

You guys have some silly ideas about crumple zones and how cars react when hit.

If you look at accident pictures, you don't ever see the body panels splitting away from each other, you see panels and frame rails bent.

Stitch welding (as long as it's done fairly comprehensively) just replaces the factory glue/spotty spot welding with a joint that's stronger (most of the time) than the metal attached to it, eliminating the joint as a flex point.

I stitch welded my S14 the day I got it, so I can't give you a "before/after" impression, but it is very time consuming. After removing your engine/interior/etc, you have to prep all the surfaces, which means lots of wire wheels (I went through 4) and a good corded drill. You should probably use acetone/denatured alcohol as well for the cleanest welds, and make sure to clean and primer afterwards so you don't get surface rust.

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huffandpuff00

My DD is fully stitched, took me a long time but i think its worth it. just dont hit anyone. do the whole thing, go for it.

Kazama1986

thanks for the help. the point about having a harder impact is kinda making me turn away from this idea. i mean it would be nice to have a chasis that stiff, but i do have to share the road with other people. the last thing i want to have happen is have someone be seriously injured because of my car. maybe one day though.

spoolandslide

so the general consensus is

stitch welded car = track only car

right?

huffandpuff00

Greg stop being a pu$$y and do the damn thang. ill let you borrow my welder and everthing.

GSXRJJordan

Hahaha does no one read my posts? If I'm going to take the time to post informative shit, people should at least browse it.

I don't believe for a second that the stitch welding I did on my S14 makes it any less safe for a passenger.

If you don't plan on putting a cage in your car, but want more stiffness/predictability out of your car, do it. I mean shit, it's basically free, if you have the time/tools. I have yet to see a downside.

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blu808

What would make it less safe is if you eliminated the crumple zones on the car.

Hi Jordan.

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spoolandslide

i have never been in a stitch welded vehicle that crashed but i would think that anyone involved will most likely be seriously injured

so

if you do it to your car and then drive it on public roads, just by having it your endangering your life and the lives of those around you... right?
like even if the accident isnt your fault

or am i wrong? cause i really dont know

blu808

Stitch welding wont really increase any impact.

If you weld up the crumple zones, or add a roll cage then you will transfer alot more energy.

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GSXRJJordan

Thanks Luke. Seriously, you're not removing crumple zones here...

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Kazama1986

well i have decided to do it. all thanks to the suttle encouragment from my friend huffandpuff. but does any do the frame rails. i mean the actual frame rails on the underside.

GSXRJJordan

What would you weld on the underside?

I weld the inner fenders to the frame rails in the engine bay... but wtf would you be doing to the frame rails? Adding flat stock steel?

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Kazama1986

I was looking at a picture of Koguchi's180sx and he had the entire underside of his car stitch welded. basically every last bit of the car has been stitched.

twistedsymphony

Unless someone has crash tested a stitch welded S chassis and compared the results to that of a factory welded chassis I don't buy the whole bad for crashing theory.

Crumple zones were developed to protect YOU the DRIVER. Unibody cars are a whole lot more fragile in a crash than a car with a body on frame design. Early unibody cars would break apart unpredictably and as a result the driver wasn't protected... A cars safety features are mostly geared towards protecting the passengers within that car, NOT the other cars on the road.

Stitch welding the chassis likely wont effect how the crumple zones work because crumple zones work by collapsing the sheet metal of the unibody NOT popping welds, even in a crash it's assumed that the factory welds will hold. Not to mention with a more ridged chassis the need for crumple zones is reduced since the chassis will act more like a traditional body on frame car, adding a cage will protect you even more.

One negative safety effect of stitch welding is the fact that crumple zones don't just make the car collapse predictably but they also make the car's chassis cushion your blow. Making it more ridged you will have much less "cushioning" in a collision.... then again your car will also likely suffer less damge... not much of a trade off IMO.


As for negative reasons for NOT to stitch weld... the biggest one I can think of is the added weight, all that metal your welding to the car adds up... I've heard that it can add well over 100lbs to the weight of the chassis.

IMO it's one of those deals where if you want to do it you'll have to strip the entire car down to the bare chassis then rip each and every seam clean and stitch it properly one at a time.

There are other things you can do to... FOAM INJECTION seems to be a really interesting technique for easily adding stiffness to your chassis without adding much weight (8lbs total). and it's cheap and relatively easy to do. It's a good enough of a technique that a lot of manufacturers are starting to do it from the factory on newer cars.

more info on foam injecting an S chassis: http://forums2.freshalloy.com/showthread.php?t=162693

you could theoretically stitch weld AND foam inject...

GSXRJJordan

link em. I have no idea what you mean, unless he added metal to the car for extra stiffness.

Hahaha. Have you even seen a stitch-weld how-to?

In order to stitch weld, you have to prep the car. First you remove all the interior/engine pieces in the way, then you strip the factory glue shit off of the seam to be welded. That shit weighs WAY more than the tiny bit of welding wire I'm adding to the car. Get real.

exactly.

It doesn't get softer, but it can become more brittle with oxidation/etc, making it crumple unpredictably anyway. His point is that you're changing very little as far as how the car reacts in a crash, as far as we can tell. Read the rest of the thread.

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twistedsymphony

Nope, I've never seen a stitch welding how to... I do know the general premiss though yes. If you read my other comment I noted that stripping the car and removing the seems was necessary.

as for the weight... I have no first hand experience but as I said I "HEARD" it added weight. I heard this from some member of my local car club who had just recently finished stitch welding an s13 hatch for use as a Time Attack vehicle. They said they weighed the chassis before and after and it added a little over 100lbs to the car in the process. Maybe they were wrong, maybe they did it wrong. Maybe they added some other kind of bracing as well which is where the weight came from... I don't know.

I make no claims that I'm an authority on stitch welding I'm simply repeating what I heard from someone who had first hand experience.

track_s13coupe

Im interesed in stich welding my 92 coupe for track use, but do you have to worry about warping the metal from heat when welding??

twistedsymphony

that all depends how good you are at welding...