Seam Welding

[omega 82]

i keep reading that a shell has been seam welded to give it more strengh and to stop flexing,but what is seam welding?.i thought you got your welder and welded all the seams fully,but now ive been told that seam welding is when you weld the seam up but space the welds out leaving a inch gap between them.

which is right? if any and does it improve a road car? and is seam welding a front subframe a good idea?

[hcmini1989 16]

i keep reading that a shell has been seam welded to give it more strengh and to stop flexing,but what is seam welding?.i thought you got your welder and welded all the seams fully,but now ive been told that seam welding is when you weld the seam up but space the welds out leaving a inch gap between them.

which is right? if any and does it improve a road car? and is seam welding a front subframe a good idea?

Can i just thow something else in here aswell before you get an answer is fusion welding stronger than say normal welding?.Sorry for the hijack

[brumster 135 1 Cars]

Omega, seam welding should not look to weld the whole seam, no. It is typical to space them apart, a run of about 1" weld then a 2" or so gap. No hard and fast rule.

 

I'm only aware of it being done on competition cars, mainly because of the abuse they get can start to pull the spot welds apart in key weak areas, but also like you say as it increases strength. Not sure of the value of doing it alone on a road car, for example - probably overkill. Getting all the seam sealant off is a bit of a headache, and once done you've got no sealed seams so the potential for water ingress is a trade-off for the strength.

[welshpug 1,621]

One small fact, probably irrelevant, Golfs since the MK5 were "seam welded" to what extent I don't know, but the shells were vastly stiffer than the MK4.

 

 

I think the reasoning behind not welding continuously is that a crack once formed in a weld will continue forming along the grain, creating a series of welds interspersed by gaps prevent this but still adds significant stiffness to the panels to warrant doing more than just spot welding.

[Rippthrough 98]

That and stitch welding like that add's 95% of the benefit with 30% of the weight penalty and much less chance of distorting the shell from the heat.

[Cameron 16]

+1.

 

I remember reading a thread (might have been on here actually) where somebody used a whole 25kg roll of MIG wire seam welding his/her chassis - and seemed to be proud of it!

[Petrolsniffer 3]

Might be a load of tosh but I heard to properly do a redtop nova/corsa conversion certain parts of the car need to be seam welded?

[omega 82]

any advice about the subframe welding?

[M_R_205 5 1 Cars]

Might be a load of tosh but I heard to properly do a redtop nova/corsa conversion certain parts of the car need to be seam welded?

 

 

i heard that a powerful red top can split the spot welds in the engine bay of a corsa/nova so potentially true....

[stu8v 68 1 Cars]

any advice about the subframe welding?

 

You can buy a specific kit to strengthen it.

[omega 82]

You can buy a specific kit to strengthen it.

 

not heard of this before,is this a main dealer part?

[Henry Yorke 269 3 Cars]

not heard of this before,is this a main dealer part?

No, this will be available from somewhere like Ab Mototsport or perhaps Peugeot Sport. It will be a bit like strut top strengtheners are also available and servo mounting plates

[Cameron 16]

I've been told (can't remember who by) that seam welding subframes is one of the most cost-effective mods you can do. Dead easy to do and it adds a fair amount of stiffness to the front end, all for about 50p worth of MIG wire.

[stu8v 68 1 Cars]

No, this will be available from somewhere like Ab Mototsport or perhaps Peugeot Sport. It will be a bit like strut top strengtheners are also available and servo mounting plates

 

TBH its pretty self explanatory where they go too. Probs overkill for a road car.

[rallysteve 22]

http://cgi.ebay.co.uk/Peugeot-205-GTI-Body...=item35a6abeb61

 

Steve

[Rob Turbo 3]

i heard that a powerful red top can split the spot welds in the engine bay of a corsa/nova so potentially true....

 

I've seen it happen! And with a seam welded engine bay the roof grew some dents just above the A pillars, not the strongest of shells!

[205wrc 16]

This is some of the seam welding work that I've done to a shell that I'm building

 

 

 

 

 

[SurGie 54]

Very nice work ^^^ I hope to achieve the same. I have tried a bit with a rented welder and it was rubbish due to the welder. I have now got my self a Portamig welder, so my welding should be much better when i restart it again.

[Cameron 16]

If you're going to rent a welder, rent the best you can i.e. a Murex or similar top brand. I rented a Murex welder to install my roll cage and do the floor modifications and it cost me £45 for 2 weeks rental, gas, helmet and gloves. Try a company called Foster Industrial.

 

Edit: No offence, but it probably was more to do with your settings / method of welding than the welder unit itself. It's more than possible to get acceptable welds even with the cheapo SIP welders, you just need to get the settings right. Also don't try doing long runs of weld, as the chances of running into a blob of paint / sealant are pretty high. You're best off having it set on a high current and doing a series of good strong tacks, as the pauses will allow heat from previous tacks to burn off any sealant that may be left in the seam.

Edited February 17, 2011 by Cameron

[SurGie 54]

Iv bought the British made Portamig 185, it does up to 6mm plate steel, so im sure it will do it well. On the Mig Welding forum they rate it highly.

 

I agree Cameron, when renting a welder get the best you can get, also prep all the work as much as possible before you higher it. I thought i had but when i was actually doing it, i found i had not, live and learn and all that.

 

Now i have bought one, it will come in handy for other things not just the cars, my advice is buy a good one for around £500 mark, avoid Clarke as they dont have the Euro torch, of which is a good quality type and is removable if it needs to be replaced etc.

 

EDIT, The instructions looked like it was for another type not the one i higher-ed and was rubbish, i did practice with it to find out the settings etc. With my practice i did some good butt welds which are the hardest type of welds on a car. I did also do some good welds but not all of them, nothing like having your own good one doing it in your own time and all that. Its harder when you are in a tight space though in corners and all that.

 

I'd not done any welding for a good 5 years so i had to relearn a bit.

Edited February 17, 2011 by SurGie

[hcmini1989 16]

Can i just add my two pence with the cheap migs i have a sip one and its crap tbh.I know you say about the settiings cam but theres only 2 to choose from so its quite hard ,Ive managed to spot weld with it but thats about it ,My cheap sip seam to feed the wire in phases like if you hold the trigger it will give you say a two second burst then cut out for a second then back on really akward to use.

 

Why does nobody gas weld shells cages etc?.Every one seems to either mig or tig

[SurGie 54]

Probably due to the amount of burned holes gas causes ??

[hcmini1989 16]

Probably due to the amount of burned holes gas causes ??

Depends on the torch ,Some can go stupidly low .Ive just bought a henrob jobby and there supposed to be able to weld stupidly thin .Ive yet to play with it yet and have read mixed opinions on them .Just thought i would have a go at seam welding with it but rather fusion welding it . But ill have to practice with it first

[large 33]

Why does nobody gas weld shells cages etc?.Every one seems to either mig or tig

 

 

Mig is a stronger weld than gas + the fact gas is harder to do.

 

 

"Probably due to the amount of burned holes gas causes ??"

 

You will not put any holes in your work if you have some kind of idea of what you are doing.

Edited February 18, 2011 by large

[Cameron 16]

Can i just add my two pence with the cheap migs i have a sip one and its crap tbh.I know you say about the settiings cam but theres only 2 to choose from so its quite hard ,Ive managed to spot weld with it but thats about it ,My cheap sip seam to feed the wire in phases like if you hold the trigger it will give you say a two second burst then cut out for a second then back on really akward to use.

 

Why does nobody gas weld shells cages etc?.Every one seems to either mig or tig

 

Amen, the SIP welders are crap. I found the trick with them is to just whack them up to max and run a load of tacks. You can only get good runs of weld if you're on quite thick material, the current and wire control is too poor to be consistent on thin stuff like Peugeot bodywork.

 

I think the reason nobody gas welds roll cages is the amount of heat you generate around the weld area, you'll quite easily burn the paint off neighbouring panels if you're not careful. With MIG and TIG the heat is much more concentrated.

Edited February 18, 2011 by Cameron