dirtdog 4 Posted July 15, 2008 A friend of mine is a welder and I'd like some welding done. I got a little rusty crack/hole under the back seats (common I assume?)which I need to weld up...I have yet to look on the underside. Can I expect it to be shot to s***? How do I go about fixing this...do I cut stuff away...or can I just attack with wire brush,weld a big metal plate to the underneath of the car, paint it and happy days? Also whilst he's got the welder out i'm thinking about seam welding, i'd like to toughen it up some. Has anyone done this to their 205?I'm guessing they use MIG? Where does it actually get welded? Thanks Share this post Link to post Share on other sites
mrswampy 0 Posted July 15, 2008 Make sure there is notheing you can damage when welding cut it back to good sound metal the new plates have to be seam welded in place then treat eachside so it wont rust again Share this post Link to post Share on other sites
dirtdog 4 Posted July 15, 2008 ok thanks.I'll just get my mate to 'stitch' the metal patch on, hopefully won't get 2 hot that way.i'll quench it with water afterwards to cool it down anyway. what kind of treatment stuff should i buy? i heard of people talkin about "crust" but i think i need something a bit more...industrial after the hole is fixed its being undersealed to prevent this in the future also i have searched for seam welding the car and cant find out how to do the shell.like..what parts get done in the rally cars.they just say "fully seam welded"? Share this post Link to post Share on other sites
DamirGTI 342 Posted July 15, 2008 Before you attempt any welding on a car bodywork unplug the ECU first ... As said , cut the holes back to the fresh metal , clean throughly remains of car paint around the hole edges (MIG welder needs surface prepare with no rust , paint , grease etc. ..) cut a piece of cardboard/paper and place it (if you can) under the hole which you've cut out .. hold the cardboard/paper in place with your hand from underneath and take a marker/pen and draw the shape of the hole from the top on the cardboard/paper by moving the marker against the hole edges until you draw the complete hole shape on to the cardboard ... next , cut the cardboard model/drawing with scissors in the shape of the hole (as you've draw it on to the cardboard ..) , then place this model on a piece of sheet metal , again take a marker and this time draw on the sheet metal around the cardboard hole model - cut the sheet metal following the markings and you'll have 95% identical plate for plating the hole on the bodywork ! This is important because you need to make as tight plate shape as you can cos it'll be much easier to weld it , it'll be stronger , and if theres no overlap in between the welded panels there will be little chances for the rust to start over again .. Afterwards protect the repaired areas - spray a few coats of zinc phosphate spray on the bare metal areas , then car paint and (if it's underbody surface ) stonechip coating on top . For surface rust cleaning use first (for initial clean up ) wire brush on angle grinder , then sanding disc on angle grinder .. then when you've cleaned the rust treat the surface with some good quality rust converter , when it's finished with chemical reaction apply few coats of car paint ..(but do buy some good un , look for the price on the bottle if it's cheap it won't be so effective ... myself have been using Loctite 7505 rust converter , it's a bit expensive , but good ..) .. Regarding the welding techniques , read this : http://www.mig-welding.co.uk/ Have fun ! Damir Share this post Link to post Share on other sites
dirtdog 4 Posted July 16, 2008 thanks damir.i got my welding technique down now,had a few goes & i think i can manage this. it's not a big hole. what is thew 205 body made out of? galvanised steel? i'd like to match the metals up..rather than welding a stainless patch onto galv'.lol anyone any clues on "fully seam welding" the car..? i have seen this mentioned to be done on lots of cars but i can't find out where actually gets welded to strengthen it up. does the floor pan get done, what else? thanks Share this post Link to post Share on other sites
James Stewart 1 Posted July 16, 2008 anyone any clues on "fully seam welding" the car..? i have seen this mentioned to be done on lots of cars but i can't find out where actually gets welded to strengthen it up. does the floor pan get done, what else? As the term suggests you stitch weld all the seams on the shell - interior and engine bay. You need to remove all the nasty seam sealer first then take the seams back to bare metal. Weld for about one inch every three inches (inch weld, two inch gap, inch weld, etc.). Personally, on the rally cars I seam weld everything except the seams up by the roof and the rear speaker holes. But they also have substantial rollcages too (Safety Devices C44 minimum) and are expected to last more than a year or two. Unless your car is stripped already or you are planning to, it will be a lot of work to get at the seams. James. Share this post Link to post Share on other sites
DamirGTI 342 Posted July 16, 2008 thanks damir.i got my welding technique down now,had a few goes & i think i can manage this. it's not a big hole. what is thew 205 body made out of? galvanised steel? i'd like to match the metals up..rather than welding a stainless patch onto galv'.lol thanks Yes please , for plating buy galvanised sheet metal 1mm thickness will be the best although you can buy a piece of 0.8mm sheet as (from what i saw) most of 205 bodywork is built from 1mm and some areas from 0.8mm sheet metal thickness . Rgs ! Damir Share this post Link to post Share on other sites
TurboSam 5 Posted July 16, 2008 Yes please , for plating buy galvanised sheet metal 1mm thickness will be the best although you can buy a piece of 0.8mm sheet as (from what i saw) most of 205 bodywork is built from 1mm and some areas from 0.8mm sheet metal thickness . Rgs ! Damir I wouldn't recommend plating it with galv, the fumes given off are poisonous and is hard to weld neatly. Although if you have to, make sure you grind the zinc off first. Share this post Link to post Share on other sites
DamirGTI 342 Posted July 16, 2008 I didn't have any problems working/welding with galvanised sheet steel ... and i've nearly finished my whole bodywork project (and there was a fair bit of patching job on the car , anyway i've lost a count in the middle of the job was a bit exhaustive job ..) But yes , by all means , i agree with you zinc fumes are dangerous Rgs ! Damir Share this post Link to post Share on other sites
dirtdog 4 Posted July 18, 2008 my car is already stripped so it's no big deal. i'll have to seam seal it again after the welding? can i buy proper seam sealer or...do i just use silicone or something? your right..the fumes are well toxic.i'll just use a fan to blow the fumes away from my face.and the only reason i'd say it comes out a bit rough is because its so thin. it's really easy to blow holes in the stuff. if it''s 1mm stuff then i'll add an extra bit of beef to it, prehaps 3mm. then time for a large dose of underseal... thx guys Share this post Link to post Share on other sites
welshpug 1,657 Posted July 18, 2008 be careful with that fan, you'l most likely just blow the welding gas away leading to even worse splattering. Share this post Link to post Share on other sites
dirtdog 4 Posted July 18, 2008 (edited) i won't be gas welding. i'll be using a mig. or do you mean gas that's given from from the welding? i have anti spatter spray anyway so it's not a problem. thanks for you concerns though ..i honestly dont know where me or my car would be without this forum cheers EDIT oops.does the mig use gas? a silly question i know but i cant remember using any..i thought it was all electric Edited July 18, 2008 by dirtdog Share this post Link to post Share on other sites
Jrod 7 Posted July 18, 2008 Mig can use gas yes, and even a little bit of wind is enough to blow away the shielding gas. Share this post Link to post Share on other sites
