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Spot welding a 240 frame?


horishima

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Has anyone spot welded a 240 Frame? I know friends do it will 240sx's and GTS's I just wanted to know if anyone has the points to do it at? How much difference does it make on the Z cars, on the GTS its a world of Difference. The main thing I found was this thread http://forums.hybridz.org/showthread.php?t=95739&highlight=spot+weld+frame

 

Thanks:rolleyesg

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Do a search on seam welding. The guy who started the thread you linked ended up seam/stitch welding his whole car. Seems like an very good idea to strengthen our rusty old chassis.

 

I found an interesting tool the other day. It is a spot weld cutter with a stop that lets you cut a hole through the top layer of metal but stops before it hits the bottom. Would be perfect for cutting plug weld holes.

 

http://www.blairequipment.com/Spotweld_Cutters/Spotweld_Cutters.html

 

http://www.sjdiscounttools.com/blr11096.html

 

Seam welding has the added advantage of sealing the joint against water.

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As Pop says, search seam or stitch. I'm sure a lot of my threads will come up. Where to do it? Everywhere. I did everything below the windsheild and the B pillar. The whole chassis basically. The time consuming part is cleaning out the seam sealer junk from the car. Real PITA. Plus getting at the seams underneath isn't fun. I eventually ended up making a rotisserie. If I were to do it again, the rotisserie is the FIRST thing I would do. You can EASILY tell which welds that were made from underneath while I was on my back vs the ones I made standing up and flipping the car upside down. I found lots of problems and fixed a lot of rust just in the process of completing this job. I feel it was well worth my time for what I intend to do with the car.

 

As to it's effect, katman has lots of racing experience and wasn't too hot on the idea, but just about every racer I know has their car stitched, and I haven't heard too many people say that it wasn't worthwhile. Johnc said at one point that just by doing that the spring rates could be upped another I think it was 50 in/lbs. If you're not aware the Z chassis is so flexy that when you start running rates over about 300 the chassis itself starts to act like a spring. The Z really needs some pretty major reinforcing if you intend to race it.

 

If you don't plan on really high spring rates or actually racing your car, it's probably a waste of time.

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  • 1 month later...

i stitch welded my drift z, it made a hugh difference,

a little test you can do before and after to see the true effect of the welding is to

1. put a piece of masking tape 1 inch across your driver and passenger door seam to the quarter.

2. use a magic marker and streight edge to make a perfect line between the seam of the quarter and door.

3. cut the tape seam with a razor blade.

4. jack the car up, from a safe jack point on one side at a time, and mesure how much the line moves.

i read this in a option magazine. do it before and after

On my 240z i stitch welded the entire car, every seam, under, engine bay, hatch, door seams. frame seams, everything. i had 10mm of play in the line before and now after welding i have less than 1mm, i added a 10pt cage also, but the line doesnt move enuff to create a gap in the sharpy marker line. so it definetly stiffened up the car,

i also added strut bars, and modified the frame rails with thicker metal, and torsion bracing under the cubby boxes.

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seam welding took more time than anything else so far... SUPER HARD TO DO!!!!! just cleaning the seams was enough to make you sick of cars for a while... then after you start welding you will end up cleaning them again and again as you keep finding bubbling trash in your weld puddles...

 

 

 

But much stiffer... ohh my.. much stiffer... Your wife will love it...

 

 

 

If you see a seam in these pics that is not welded... It has been welded since I took the pics... I went through a 20lbs spool of wire and 2 tanks of gas... and then a lot of grinding wheels to clean up dirty welds...

 

 

completedfrontendreinforcementwitht.jpg

 

completedfrontendreinforcementwi-1.jpg

 

Firewallreinforcement.jpg

 

towertoswaybarreinforcement.jpg

 

 

 

 

 

 

SFCtoTCcupjunction.jpg

 

SFCfrontframearea.jpg

 

SFCrearangle.jpg

 

 

completedseatmount.jpg

 

 

rearhoopdiagonals.jpg

 

 

 

 

 

rearuppercrossmemberreinforcement.jpg

 

fuelcellframeskin.jpg

 

leftstrutplateinstalled2.jpg

 

firewallbracing.jpg

 

 

 

 

framegussetscomplete.jpg

 

framecrossmembermountingsurface.jpg

 

framecrossmemberreinforcement.jpg

 

 

 

 

 

....

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