Welding issues with new trunk thin metal

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PostPosted: Fri Oct 28, 2016 2:52 am
I hired somebody to weld in a new trunk basically from the spare tire back to the license plate area as mine was rusted. Unfortunately holes are forming during the welds, he tried stick and flux core. It appears the very thin metal on a honda del sol is difficult to weld.

I am new to welding an not an expert so im not sure if the guy is doing it wrong or using the wrong welders, but my idea was to do some spot welds and then go over it with some automotive waterproof caulk in order to seal everything.

Would that work well, or should the entire trunk be welded?

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PostPosted: Fri Oct 28, 2016 7:46 am
Obviously you do not have an auto body man doing your welding.

MIG (with gas) or TIG is a much better way to go. Also a skilled man with a torch could do it.

Entire seam should be welded and when ground even to metal surface should be undetectable or very near to it.
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PostPosted: Wed Nov 02, 2016 2:17 am
thanks i will look into this further and find somebody with the appropriate welders



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PostPosted: Fri Nov 18, 2016 7:59 pm
I have a concern about the metal on the opposite side of the weld rusting out, i have no access to it after welding so i wont be able to spray any primer or treatment onto it

I have looked into galvanized paint or weld thru paint which i could potentially spray on both sides of the metal and hope for the best, im still researching those products

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PostPosted: Fri Nov 18, 2016 8:35 pm
Weld thru primer would be your best choice if you have no access.
Generally trunk floors are spot welded to the frame rails/floor supports. What I do is pre-drill the holes to be spot welded, coat frame rails and back side of new panel with epoxy primer. Then set the panel in place and fasten with C-clamps or screws (removed later). Using a flat bottom drill or end mill of the appropriate size I clean the metal inside of each hole before welding.
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PostPosted: Sat Nov 19, 2016 4:43 pm
The part of the trunk that i have was not spot welded as it was cut out all the way through

After you weld, wont the heat melt the epoxy primer off the backside?

I just got some rustoleum galvanizing paint from home depot and sprayed it on a scrap piece of metal, i welded a tiny bit with my flux core to test and it seemed to have burnt off the paint from the back side and this was on i believe an 18 gauge piece, the trunk is about 24 gauge
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PostPosted: Sun Nov 20, 2016 9:17 am
I butt-weld thin metal all the time. It shouldn't get that hot except in the places your welds are. Basically you place small tack welds about 3" apart all the way around the where the two pieces of metal butt up. Then you can add a tack to each weld in succession and repeat until the entire seam is welded. On smaller length seams you may have to wait in between welds for the metal to cool back down.

If you are planning to overlap the metal edges, you might consider panel adhesive instead of welding.
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PostPosted: Sun Jan 22, 2017 2:06 pm
I am a novice welder myself and was having the same issue with burning through all of the time on my patch panels. I switched welders from a flux core to a gas unit and that helped some but I still burned through quite a bit. I was picking up some sheet metal at the local metal place and started talking to a guy who had a welding rig on his truck. I got him to come back to my place and take a look at my setup. He changed a few settings and that made a world of difference. He was not even going to charge me for his time but I gave him $60. It was well worth it.
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PostPosted: Sun Jan 22, 2017 5:20 pm
this is a good chart on how to get your mig welder set close to what you need, it gets you close, it narrows it down and you might have to make a few adjustments...... the column on the left is your metal thickness.... then across is your wire diameter , note that each wire diameter has a Factor number with it,....example , .030 is 2, say your metal thickness is .125, so multiply your metal thickness times that given number which for .030 is 2 so your wire speed should be 250, now to get that number cut your wire flush with the tip, pull the trigger and count to six, measure the amount of wire that came out and add a zero, so if I pulled the trigger and got 30 which equals 300 I know I need to slow my wire speed ..again this helps get you close, most mig machines are cc-cv, which is constant current -constant voltage , as you turn the wire speed up the voltage adjusts with it...... if you have a separate voltage dial you can adjust accordingly, more voltage will flatten your bead...
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PostPosted: Mon Jan 23, 2017 4:13 am
xboxhaxorz wrote:The part of the trunk that i have was not spot welded as it was cut out all the way through


I don't know what happened to your pics of the Trunk pan?
Any Way looks like those Pieces are just over lain over each other and Spot welded together as well as Glued If I would have to guess being its a newer car. It may have been only glued in ??? only person who removed it could say for sure.

It looks like the Panel to be installed May have been hastily removed and may need some repair were it over lays car structure ?

I would clean up all along all edges top and bottom of both sides of each panel that over lay to bare metal put the new panel in and drill holes through both pieces and put sheet metal screws through it to hold it all together or use Clecos to hold the panels together.
Once you've got a good tight fit all around whole panel and its solid then At that point you could Use Panel adhesives to bond it all together BUT I would consult the factory structure manual first its probably installed using a combination of Spot welds And Adhesives. Or it could have been all spot welds I'm not familiar with that kind of car and as such consulting the correct repair manual for each car make model and year must be done.


Doing this repair while elementary in skill level has extreme responsibility Your messing with the cars Structure To protect the cars occupants and while you say ah its just me no one else and I'm never gonna sell the car guess what some way some how some kid gets a hold of the car in the future as his first cheap car & gets rear ended but the Trunk wasn't installed correctly the Two kids Traveling in the back seat where killed instantly on inpack Just because the Previous owner was trying to save a few bucks. Consult the correct manuals! They will have step by step instructions for replacing that panel.
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