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Making Rust Replacement Sections

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HI guys

This is just a quick run through of small panel making for rust repairs




Well as you can see I have an unwanted vent in my roof so I thought I would go through the pattern making process with this and also I’ve done the inner dog leg on the passenger side.

With any section you need to make you want to try to do the least amount of work to the area that you see the most so if you do need to cut and weld or add a wedge it’s on a lip or hidden. Sometimes this is impossible so hopefully your metal finishing skills are ok.

I have found when doing small areas the best thing to use for the pattern is a sliced open brown paper bag like what your mum used to pack your lunch in, You don’t want to use paper that is too thick as it’s a pain to push it into the corners and keep flat, While paper that is too thin by the time you have finished what you need it for its ripped and out of shape. If it’s a bigger panel  I use the brown masking paper used for masking cars up but something similar to the humble paper bag will be fine.




Now first of all I sit the paper on the panel with some magnets to locate it where I want to copy the sheet metal underneath, With the roof I started on the top as I want to do the least amount of work on the top, when happy with the position I cut some small holes with a knife and stick the paper down with masking tape making sure that you keep the paper as flat to the panel as you can.




Slowly make your way down towards the gutter, No need to worry about the wrinkles * as this shows you the areas of the panel that you will need to shrink. Keep going until the entire roof section is nice and flat. Definitely don’t cut the wrinkles just get them as flat as you can, It’s more important to have the overall pattern smooth on the surface.

Then work the paper into the gutter making sure it’s hard against the panel, you may have noticed I am making the pattern on the other side, this is purely because masking tape doesn’t stick very well to air. I will flip the pattern when I transfer it onto steel. This can be done for most areas but if both sides are bad you will just have to do the best you can to keep the paper in the right spot. This is reasonably important to make sure the replacement sections is spot on but it isn’t the end of the world if it’s a bit out.




Once the roof and gutter section is done use a pencil to mark the fold lines * in the gutter and the top of the hatch opening.  You will notice the area where I have placed a magnet in the hatch opening * is tight and you will not be able to push the paper around the opening.




This will require a few cuts with a knife so you can continue with the pattern but does not affect anything and this is an area you will need to stretch the steel.




As with the gutter area work the paper into the lip and mark all the fold lines * with a pencil. Then carefully remove the pattern from the car and trim it where required. Try not to leave to much extra on as it will make the shaping process a little harder and if you got the paper on nice it will fit up perfect anyway.




Remember the areas that wrinkle * need shrinking, the more wrinkles the more shrinking required. The areas that you have had to put a slice in * to get the paper flat on the panel will need to be stretched and in your shed at home stretching is easier than shrinking. Sometimes without the right equipment you may need to do a relief cut or add a little wedge.




Now the inner dog leg

First I started with the vertical surface # stuck on first (I used magnets because it was quicker for this purpose but when actually making the pattern I would tape it on) then had to slice the large section # closest to the inside of the car to make it go and will require a fair bit of stretching. The outer most part #will require a lot of shrinking especially near the purple line and may even need a relief cut, Notice all the fold lines marked with pencil so I know where I need to fold the flat steel.




Pattern trimmed ready to transfer to steel.




Ok first thing now is to stick the pattern down to a similar sized piece of steel, 1mm is fine I wouldn’t go much thinner it’s good to leave a bit for file finishing, much thicker is harder to work. I use the existing tape holes but just put a new piece of tape on. Mark around the edge with whatever you like I have used texta purely for the sake of pictures normally I just scribe. For all the fold lines I use a Stanley knife and just do a 3mm cut every inch or so along the line so when I pull the pattern off it’s just a game of join the dots. Then cut the steel to a few mm bigger than the pattern so you can flip it over and mark the other side the same way and get the marks in the same spot.




Then using a small chisel I go along all the fold lines on the back of which ever direction that fold will be, you don’t have to hit hard it’s just to help the steel bend in the direction you want and makes it easier to see where you need to fold latter especially after you have beaten the crap out of it. As you can see in the pic it has made the steel move in the right direction.




Next I use a hammer on a sand bag to start forming the desired shape, depending on what and where will determine what I use. If you don’t have a sand bag then try a pile of rags or even just a pile of sand on the ground. Now I will go into detail with the roof section but I have also put up pics of the inner dog leg. After I have got it going in the right direction I had to do some shrinking were the wrinkles where on my pattern, either heat shrinking or a shrinking hammer will do this but will take some time. I used our shrinking machine to save me time.




Then I bent the gutter edge over to support the roof section and dressed it up a too probably 80% done so it would keep its shape whilst doing the rear hatch gutter channel.




If you look back when I made the pattern for this on my car I had to cut the paper to get it to follow the shape of the body so this area will require stretching. So I sit it on the sand bag and pound the s##t out of it using a ball peen or similar hammer that doesn’t have sharp corners or it will tear the steel.




Every now and then turn the panel over onto a flat surface and hit the edge back down so the roof is back in shape again. Its basically just this process over and over until it goes where you want it to but take your time.




Then just fold up the inner lip a bit more dressing up and it’s at a point where you can cut the section from your car and trace that onto your new section and cut it to size. The new panel may require a bit here or there when you start to fit it up and this will be dependent on your skill level etc.




With the inner dog leg I had to stretch it a fair bit and got a small split on the inner edge which I welded up but apart from that it was all good.








Now as for welding sections in I will always Oxy weld where possible, if I can get a dolly behind the panel I will always Oxy. The MIG is great when you don’t have access but that’s it. Yes I hear you all saying the panel will warp well Bullocks, If you know what you’re doing it is the best way to weld as you can still heat shrink and metal finish correctly as the weld is nice and flexible just like the panel but MIG is hard and brittle an if you have to work around it too much your panel will split.


Well I hope this helps some of you guys out or at least points you in the right direction.


Earlier I mentioned that I used a shrinking machine to shrink the metal to save me time. This would be one of the best machines you could get for metal work, there are a few types available and they range from a little over $100 to a lot. Also on evilbay as well. Get one that does shrinking and stretching and if you can get a deep one to get in further than the edge and the world is your oyster.














Link to Oxy Welding Page



Link to FB page



Check these guys out



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I hate to add a post of no value to this thread, but thanks so much for sharing this information and providing those excellent photos. Really appreciated and thanks Lurch for making it sticky, definitely valuable for everyone in the community.

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Thanks gentlemen

More than happy to do this, Soon i will add a some info on Oxy welding

sections in, There is a knack to it and it takes longer then MIG but the

end result is far superior.


Please add your pics of rust sections that you attempt this way.


If you have any requests for a certain area let me know and if my car is rusty

there i will post pics of that as well.




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HI Mick

TIG is pretty close to Oxy in the way the weld is still workable.

Problem with TIG in this situation is it takes a similar amount

of time to do but you use so much more gas and as pure Argon is liquid

gold it makes it more expensive. For some reason customers don't like

more expensive.

That being said i always use the TIG for building up the edge of a door,

boot skin to get a sweet gap as you have so much control over the heat

it doesn't effect the panel too much and you can still work the edge where MIG

makes the edge brittle and wants to split. But there is nothing i love more than

running an Ally bead along the edge of a catch can or similar.

Keep an eye out man i will do a spot on welding in panels soon, Not just the

actual welding but also the best shape for your panels when you put them in.

I am sure other people have different opinions on this as it is really dependend

on what your workshop is setup to do. Same old argument really you have to balance

cost and quality to meet the customers needs.

Everyone want metal finished body work for $2.50




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Hi Paul, it's nice to see how the metal forming is done properly. I was reading the step by step instructions with interest . And to see the results was amazing. I did a lot of this sort of thing when building my blue 240z eight years ago.( not of this high standard ) I love your work and wish this was around when I was building my zed. In hindsight I think if I ever did it again I would leave the body work to guys like you and Lurch. And buy the way may I ask if this is your line of work or a passionate hobbie. Great work Paul.

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GL240, Yes i do work in the industry and have so for a while now.


Thriller, did you get that car from the auctions


Mick , When it comes to welding steel yeah i reckon the oxy is heaps cheaper to run

        From memory an E bottle of Oxy and an E bottle of Acetylene come to around the

        same cost as an E bottle of Argon so you effectively have twice the gas, Not just that

      when welding steel your Oxy setup is very low pressure where with the TIG you are running

      4 times as much pressure to keep the tip and weld nice. Although you are paying the rent on

      an extra bottle, but you can also Cut, Heatshrink, Heat to bend, anneal, Lead load and if you are

      good you can also Ally weld with the Oxy. No power bill and no tips to replace.

      Mate if you can TIG weld good you will make Oxy welding your bitch.


      Most people are a bit scared of Oxy welding a car panel from fear of wrecking it, I just finished replacing

    a whole corner of a Karmen Ghia bonnet at work probably about 20% of the area of the bonnet, All Oxy and metal finish.

    You just have to know how to do it.





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Than mate. I have been getting in to a bit of custom motorcycle work. Mainly caffe racers I have been collecting some tools I now have an English wheel and an air hammer I was going to buy a tug next but now I think I might go oxy instead. I have been using my hollowed iut wooden stump and a mallet to do some shrinking but I also need to get a sand bag.

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Nah mate, went for a few hundred more than I wanted. Decided I was only going to go through with the hassle if there was pretty much a guarantee that I'd be much better off doing it, than buying a clean one already. Cheers for the help though, will be good to keep the info in mind when a similar one pops up for round 2.

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Awesome Paul.  ;)


Although not technically rust, do you believe that it is possible to fill a sunroof hole with a metal section?


If you stepped into his shop, there would not be a shred of doubt left in your mind hahah.

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Mick if i didn't have access to this gear i would buy an Oxy over TIG every time, I think a good torches

      kit is around $600, If it doesn't have a .6 tip then get one as that's what you would use for car panels

    and if you wont use it much get the small bottles. That's a good collection of tools you have man, grab

    shrinker/stretcher set or pay a bit more and just get a deep one as they usually come with heads that shrink

      and stretch and it only takes 2 minutes to change the headsit will be the best thing you have ever bought.

    Old stump is a great thing to have as well.

    Old bike stuff is cool, allways been a fan of the old Harley's, We are actually restoring a 39 at the moment with

    a big cube flat head engine. Cant wait to hear it.


Roberto,  Yeah its not a problem to do that. There are a couple of ways to go about it. Easiest is to get a donor

                roof and change them over but the price of them has gone up  and up, Next easiest is for us to roll up

              a section and cut it to fit into your existing opening, We would fit it flush and Oxy in so you would be almost

            undetectable. Other places would cut the replacement 10mm bigger all round and rebate it then MIG it in and

            Bogs your uncle.  Then would be make and entire roof section basically the same way i made the roof corner and

          remove your roof skin and replace with the new one.For cost i don't quote but i would allow around 400 for us to put

          donor panel on, around 1000 to make a section and Oxy it in and probably 2000 to make and fit new roof, As i said

          these are not quotes.




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I have just recently done my first rust repair sections. First time I have tried, cheated a little with the first piece I made and cut and welded the top of it, reckon I could have just shrunk it but I was getting too impatient.


Oh yeah, it isn't a Z ;D


Started with this.



Wanted to try the back corner first so that I could prove to myself I could do it before I went too far.





Then I went and did the larger section, no cut and shuts on this piece. It is all welded with a mig (don't have an oxy/tig). Will get one someday, but for now will just have to live with using the mig and using more lead/filler.







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Good Job Garvice, Best spot to practice on is under the car that's for sure.

There is nothing wrong with using the MIG just take a little bit more time getting the shapes

as close as possible along the weld line and make sure they are flush with each other when you

weld as you wont be able to work it as much compared to Oxy.



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One thing that I have found useful for hot shrinking where you don't have an oxy or don't want to splurge on a good oxy and cylinders is MAPP gas. Bought a torch and cylinder from bunnings to do copper piping, but works very well at getting the sheet metal blue hot (or red hot if you leave it on too long) so that you can beat the high spots down and shrink the metal. Used it along the bottom flange of that large section as I had curved the top and had to straighten the bottom a little.


Gas was even hot enough to be able to bend 12mm reinforcing bars.

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Horrible worn out over used beaver




Nice Virgin Beaver


Maybe guys when posting to save the thread getting to busy just keep it simple here,

by all means post heaps of pics in your build thread and maybe a link in this post but would be

nice to keep this thread as an info thread.

Garvice what you have posted is fine this isn't directed at you but it got me thinking of setting

a basic rule to try to minimize the thread, Nothing worse than going back through pages of stuff.




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  • 4 weeks later...
  • 3 months later...

Had this problem with the rear wheel arch (on a 1600).



This was the final panel welded in



Unfortunately I didn't take many in progress photos. So to try and show you what I did, I went out tonight and recreated it with cardboard. Please note, I didn't use cardboard as a template, the cardboard you see is just representative of what I did in metal.


Started by making a quick form out of 1/4" rod which matched the upper curve of the wheel arch to get a bit of a curve started in the metal.



I then did a very quick bend over the form, I only got a very small shape into the metal, but did concentrate on making larger dints where you see the little black dots. This was so that I could clamp it closely to the wheel arch and use the wheel arch as a hammer form.



I then clamped it to the flare like this and started working on folding the bottom flange under. I did this with lots of quick light taps on the v marks. I also didn't fold it all the way under, probably got to about a 45deg section to start with (as you fold the flange under it wants to buckle away from the wheel arch).



Then I worked on the edge of the wheel arch to get the metal back towards the wheel arch (had only come out a couple of mm).



Then lots of little taps on the top of the wheel arch, and all over. I basically went back and forward, top and bottom and on the wheel arch all over the place. Using the wheel arch as a hammer form worked great.



I then cut it out using a large radius (thanks for the tip Ledge, helped minimise distortion) and welded it in.



More photos can be found on the build thread http://the510realm.com/viewtopic.php?f=3&t=24424&start=15#p209195

Apologies if there are too many photos.


I found that a light (200gram) ball pein hammer was best for this job. Used the ball part for the top of the wheel arch and the flat for the bottom and front of the flange. The ball pein came in handy as even the flat section has a bit of a radius around the edges so it didn't leave any hard marks.

I also started this panel trying to use a stretcher, but since mine only stretches the first inch of the metal I couldn't get it to stretch that large radius of the wheel arch.

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  • 2 years later...

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