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seam welding

Jerd

Jerd

Active member
Joined
Mar 1, 2008
Location
Vancouver WA
Will it do any good? If so im going to do it right now.

What are some good locations, share pictures?
 
You don't really want to lay down continuous welds - you want to weld for about an inch, leave a gap of about an inch, weld for about an inch, etc.

It does help body rigidity and lifespan, but don't go thinking that it will be an amazing difference. This is particularly true of a 200+ Volvo that it pretty rigid to begin with.

If you ever need to replace a corner/front cut that's been seam welded, you'll be hating life.

Lots of info on various rally sites around the place. Everyone has their own theory about the best parts/places to do on each car - but its kinda like head porting: Everyone can find something to criticise about other people's work/decisions...
 
Spac said:
You don't really want to lay down continuous welds - you want to weld for about an inch, leave a gap of about an inch, weld for about an inch, etc.

It does help body rigidity and lifespan, but don't go thinking that it will be an amazing difference. This is particularly true of a 200+ Volvo that it pretty rigid to begin with.

If you ever need to replace a corner/front cut that's been seam welded, you'll be hating life.

Lots of info on various rally sites around the place. Everyone has their own theory about the best parts/places to do on each car - but its kinda like head porting: Everyone can find something to criticise about other people's work/decisions...
Click to expand...

Yeah i figured, i have seen a few pictures and i got the main idea down, im sure the goal is lots of penetration.

Im sure every car is different, thats understandable sounds like i ether just have to be choosy of the places i want to weld, or just weld it all hahaha.

Idk ill scope it out and make up my mind weather i want to dig into it today. Looks like some of the best places would be in the engine bay and i dont really want to do that right now.
 
Spac said:
It does help body rigidity and lifespan, but don't go thinking that it will be an amazing difference. This is particularly true of a 200+ Volvo that it pretty rigid to begin with.
Click to expand...

Not sure I agree with that. It might not be a massive difference on a brand new 240, but at this point the newest shells are over 15 years old. They invariably get flexy after 100k+ miles on the road. Almost all 240s I've seen have shown cracking or separating around the hood hinge area. You've got 5 or more different pieces of the unibody all coming together in one place. That's probably one of the first places I would add some weld to.

You can also do as (I think) John V has suggested and go around all the door and window openings with a spot welder. That supposedly does a lot to stiffen up the chassis.
 
Karl Buchka said:
Not sure I agree with that. It might not be a massive difference on a brand new 240, but at this point the newest shells are over 15 years old. They invariably get flexy after 100k+ miles on the road. Almost all 240s I've seen have shown cracking or separating around the hood hinge area. You've got 5 or more different pieces of the unibody all coming together in one place. That's probably one of the first places I would add some weld to.

You can also do as (I think) John V has suggested and go around all the door and window openings with a spot welder. That supposedly does a lot to stiffen up the chassis.
Click to expand...

I am yet to see a 240 cracked in the area you've mentioned. I guess those extra braces that most Australian cars were factory fitted with, do actually make a difference?
Similarly, I don't reckon that 240 bodyshells get as tired as most other cars - I can drive any old Mazda and within a few kms it is apparent whether its a good shell or a floppy one, regardless of the quality of the bodywork, suspension work, etc. I am yet to drive a 240 and think "This one's gone floppy".

None of which to say that there's no benefit to seam welding the shell - just that you shouldn't expect miracles (unless the car has been pounded to death already, and you're restoring body rigidity).

Interestingly, one of my 240s has a fatigue crack in the rear 'firewall' (ie: behind the LHS rear passenger's left shoulder) which I'd never seen before - no other signs of a hard life, although its taken a thump to the LHR sometime long ago (possibly related to the crack?).

The door & windscreen openings are important.
A friend did some experimentation with his Datsun 510 a few years ago (a 510 is a similar shape and proportions to a 244, so its reasonably valid to use his conclusions). He did actual testing of his old body shell, and also built a balsa wood model.
The two biggest things that made a difference were:
1. Bonding the windercreens (F & R) into place, rather than the original 'press in rubber' - obviously not an improvement for a 240 as they're already bonded;
2. Stiffening the door openings. His was a rally car, so he was focussed on building a rollcage to acheive this, but the lesson was still valid.
 
alexm963 said:
i think he meant a 2000 or newer car not the newer 200 series
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Actually meant 200 series and newer.
Having pounded my 164 rally car to death, and then built the 244, its interesting to see that when Volvo designed the 200s, they improved all of the problem areas that I discovered in the 100.

The new stuff is out of my league, but general experience says that they are much stronger in most ways (thanks to airbags removing the need for traditional crumple zones, basically).
 
Spac said:
I am yet to see a 240 cracked in the area you've mentioned.
Click to expand...


large.jpg



My car started trying to literally break in half right there a few years back.

Airtime is fun.
 
Spac said:
Actually meant 200 series and newer.
Having pounded my 164 rally car to death, and then built the 244, its interesting to see that when Volvo designed the 200s, they improved all of the problem areas that I discovered in the 100.

The new stuff is out of my league, but general experience says that they are much stronger in most ways (thanks to airbags removing the need for traditional crumple zones, basically).
Click to expand...

The crumple zones are still there in modern cars to absorb energy in a serious collision and help protect the safety cell, airbags don't protect the legs and feet.


Cars will vary widely, but both the material and the factory welds themselves can tire with use and on a car intended for rough stage events both additional spots and intermittant seam welding can help extend their life.

On these sort of cars it is important not to continuous weld to allow some flex otherwise the loads can just be transferred to a weaker area and cause problems there.
Tarmac/ circuit car chassis are often much stiffer to make better use of weight transfer into their suspensions, but much of this can be done by utilizing the cage structure tied into the body and suspension pick up points as far as permitted in the regulations.

It might help to imagine the kind of impact loading and stresses that different areas of the car experience with your kind of use, and weld/ reinforce those accordingly.
 
This is my attempt at seam welding. I cut this piece of metal out of a spare trunk lid to stiffen up the rear. It ended up taking alot more time than I figured it would. Put a couple of coats of quiet car on it after.
 

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yama said:
This is my attempt at seam welding. I cut this piece of metal out of a spare trunk lid to stiffen up the rear. It ended up taking alot more time than I figured it would. Put a couple of coats of quiet car on it after.
Click to expand...

That used to be a common way to add body stiffness to race and rally cars, particularly when everyone used to run bolt-in aluminium rollcages.

Interesting to see so many people keen to defend seam welding. Maybe I should clarify my stance?
1. It will make a difference. Whether its worth the effort, and whether you'll ever feel the difference depends a lot on the type of car, the particular car, and what it will be used for.
2. A welded in roll-cage will increase a body's stiffness by a LOT more than even the best seam-welding job.
3. There are many other ways to increase a unibody's stiffness (such as Yama's welded in rear firewall).

I guess my point is that it has its place - typically on rally cars, and (to a lesser extent) in big power cars. If you have access to a MIG or oxy welder, then its cheap to do (albeit time consuming to do a decent job). If you're serious about improving the stiffness of your car's bodyshell, then there are other more effective methods to acheiving this.

This is my Mazda 808 (Mizer?) rally car. For it, I consider the seam welding to be essential, along with the plates on the chassis rails, a good strut brace, etc. I rallied this car without seam welding back in the day, and it fell apart spectacularly quickly - cracks began to appear before the end of its second event - and this had been a better than average bodyshell.
It then took a lot of work to get it back into shape.
Enginein2.jpg

FrontDriversStrut.jpg


In contrast, we did several thousand kilometres in a heavily laden, un-seam-welded 84 244, over lots of rough dirt roads. All with rubbish shock absorbers.
It then did several khanacrosses (where it got flogged by a number of different drivers), covered several rally routes, and was generally mistreated... Despite all of that, we found no cracks or other signs of floppiness.

This is why my new 244 rally car hasn't been seam welded. When the motor & dash come out, I'll weld it up, but its not a pressing issue - not by a long way.
 
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My car creaks and the plastic moves around when hitting bumps and going over imperfections/up angled driveways and such. It flexes. It now has almost 160k on it, and the last 60k have been hard street driving mixed with a few very aggressive(and bumpy) autoxes and a few track days. I would LOVE to stiffen the floppy thing up. A strong chassis reduces the need for stiffer suspension as well as doesn't allow as much road variation to enter the cabin. I'd love for my car to be seam welded and filled with foam to add stiffness, dampen vibration and noise. Maybe one day.

Then again, that would require full disassembly, removal of good paint, and lots of time/money. One can wish though. :( Or maybe Volvo could just come out with an updated 240 that is still a 240 with none of the electronic whizmo crap that makes all new cars suck. Yeah.
 
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