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When seam welding does the whole seam get done? I was thinking my tipo could use a liitle more power and thinking along the line a little, i wondered if seam welding is a good way of increasing body strength. Also what seams to weld? The pictures i have seen have welds every couple inches. The car will have strut braces also. Because it is a road car no cage will be used. Cheers for any help.

Terry

You have to be careful seam welding so as not to twist everything out of shape. This is one of the reasons you stitch an inch, leave two. Some seams don't need it, and you would be wasting effort to do them.

You also dont want to start in one place and go straight along one seam.... you have to move around to other places around the body, so as not to concentrate too much heat all in one place....

You also have to make sure the seam is clean... no paint or underseal, or you will get porous welds that contribute little if anything to the stiffness.

It certainly can increase the torsional stiffness of a chassis, conbined with some creative triangulations in high stress points (don't ask me where they are on a Tipo, never worked on one) can really make quite a difference.

Triangulating where chassis members join the firewall/bulkhead usually pays good dividends in strength gained against time spent and added weight.

Talk to other tipo racers and ask them where the main chassis weaknesses are.

Look at some smashed tipo's and see where they buckled like they are meant to.... and leave those areas alone. Otherwise you will diminish the effect of any crumple zones, and in a heavy impact more of the loads will be transferred where you (probably) dont want them to...

SteveC

apart from talking to racers about their experience, how can you go about working out which seams need welding? (inc any books that cover it well)

i'd always thought you'd weld the whole section (over a time due to heat eg - 1 leave 2, 1 leave 2 etc, then go back and go along and do another inch leave 2 etc). unecessary?

Cheers Steve, yeah know the basics about making sure not to weld straight along the seam. Will look for racing tipos and get a idea. Have looked at sedici richs race car and he gave me the thought. I thought the first three metres of a 80s fiat is the crumple zone

Sweet, my 1990 Uno must be safe then

steve have you got any info for a 124 other than what was posted in the other thread by BT? if so please enlighten me

how tough is it to get a car past rego if its been seam welded? i imagine in a car that predates ADR's it shouldnt be an issue...

Provided it predates any requirements for progressive crumple, I wouldn't have thought it would be an issue. It's not as if many people are actually even going to notice it once it's painted over.

Hi Terry,

I felt a big difference in how much movement there was in the door openings before and after seam welding the 128, and i think most of this change came from the reinforcing and seam welding at the firewall. Crumple zones aside, I have a hunch that all the panels/sections that go across the car (on an enclosed roof car like a tipo) contribute more to torsional strength than those that run along the car - like the firewall and where it joins to the body, or any box sections spanning left to right of the rear suspension, and where they join to the body at either side.

I also have a hunch that to improve the lengthwise torsional strength of the car, there's a limited amount you can really do besides put in a roll cage - as you say not ideal for a road car...

You'll end up with a big improvement on standard even without a rollcage IMHO, coz the suspension at each end by itself will hold its geometry better under hard cornering.

Will

I had every seam that could be seen welded, crumple zones mean nothing with the cage and the triangulation, but of course th I have a 6 point harness and race seat. Whats it worth not sure, but the tipo shell isn't very strong, the whole thing would crumple in a crash, esp with a turbo engine.

rich

when i jack my car up under the crossmember, or put stands on the rails, you can hardly open the doors. im a bit worried about this especially with the engine im proposing. im thinking a cage is a must, as much as i hate to do it