One of the biggest problems we have to deal with when it comes to old vehicles is Iron Oxide, aka rust. This stuff, if not dealt with, will literally eat your car away to nothing. Because we primarily talk about classic muscle cars in these pages, its pretty much guaranteed we will see a lot of rust. Case in point is a 1970 Z28 Camaro we have been wrenching on. The car is pretty dang solid, but the driver's side quarter-panel has some serious rust going on. We like the car and want to keep it around, so it was time we bit the bullet and got busy fixing the quarter.
We have been around body and paint shops long enough to know that a full quarter replacement is pretty involved, but nothing a person with some common sense, a welder and a few special tools couldn't handle. We think we fit that bill, so instead of passing off the work to a shop we decided to roll up our sleeves and try it ourselves.
The job will take some special tools to complete, most notably is a welder. We have an older Lincoln SP-100, 110-volt wire feed that handled the job great, but those have now been replaced in the Lincoln line with the Power MIG 140. You will also need some special clamps, a grinder, a cut off wheel, and some blocks, but those can all be ordered from Summit Racing. There were some items we didn't have on hand for the job, like body filler and sand paper, which we were able to get in one stop at Summit Racing.
The key component to the fix is going to be the sheetmetal, and we decided to go straight to Auto Metal Direct (AMD). We ended up ordering a quarter-panel and some supporting pieces, which we'll go into more detail about later in the story. We have all heard the horror stories of what some body guys have had to do to make lesser quality panels fit, but in our case it all fit, which made the job for rookies like us doable. This was the most involved bodywork job this author had ever done, and thankfully I did have some help in the way of our local electrical guy, Lucky Costa. I will say that I consulted a few professionals for advice on how to do a few things, and we got a few different opinions. The following story is the route we decided to take, and it came out great, which probably has more to do with good parts and less about skilled labor.
Our subject vehicle is a '70 Z28 that (obviously) has some serious rust issues. Not only is the quarter covered in some pretty bad surface rust, but the front and back of the wheelwell are beyond saving. The car was put out to pasture, so this rust was never stopped and now it's too bad to fix with just a couple of patch panels. We already know that we will be using an AMD quarter-panel for this repair, but we need to get the original quarter off to know the full extent of the rust damage and if we need any other supporting pieces.
Step one is to unearth the factory roof-to-quarter seam and remove the lead. After sanding off all the old primer, paint, and body filler, we found our lead to be removed. We decided to melt it out with an oxygen acetylene torch instead of trying to sand or grind it out. We kept the torch moving so we didn't put so much heat into the panel that it would warp.
We used a few different tools and procedures to get the bulk of the quarter off. In the areas where the quarter has a sharp edge (like the rear window area) we used a grinder to cut off the corner, and a putty knife to open up the separation. This leaves the welded joints intact, but makes getting them off much easier later on.
For the bulk of the removal, we used an air chisel with a cutting tip to quickly cut the metal. We could have also used a plasma cutter, air saw, cutoff wheel, but this was the quickest. We made sure to stay away from the edge at first to prevent hacking up anything hiding under the quarter.
After consulting with a few body guys, we decided that we were going to butt-weld the roof seam instead of trying to slip the quarter underneath the way the factory did. We carefully made a straight cut along the old quarter with a cutoff wheel. Now we could address all the leftover remnants.
Back at the taillight panel area, the quarter is held on with a few small spot-welds and seam sealer. Some wiggling with the pliers was all it took to break it free leaving the taillight panel intact. This would not work if you tried to get the quarter off in one solid piece, so maybe now our reason to quickly cut off the bulk is becoming clear.
The majority of the welds holding the quarter on are made with a spot welder, so we used a spot weld cutter to remove the material. These cutters work by cutting around the perimeter of the spot-weld, allowing you to remove the piece with minimal damage to the underlying metal. Cutters like theses are available at Summit, but we already had one.
After using the cutter on all the spot-welds, all we had to do was pry up on the piece. There will be small round discs of old quarter that are left behind but these are easily ground off, but more on that later.
There is an area where the spot-weld cutter just wont fit, and it's in the gutter of the trunk seal. We used a cut off wheel to carefully grind away the spot weld being as careful as possible to not grind away the lower metal we are trying to save.
We found that our trunk extension (trunk drop off) was beyond saving, so we used the chisel to quickly remove most of it and then came back to clean up the area. Where the trunk drop off meets the trunk floor is edge-welded, so cutting the welds with a cut off wheel and then prying it apart was the was to go.
The drop off, quarter and lower valance all converge below the taillight panel and we used the air chisel to get the quarter and drop off panel remnants off the valance. The factory installs the taillight panel/lower valance last so we will no be able to weld the new quarter on like they did, but we have a cure for that.
Another area of multiple panels converging in one area is at the bottom where the quarter meets the rocker. There is an inner brace for the striker pin that runs from the roof all the way down to the rocker. What makes this a pain to deal with is the quarter is sandwiched between the rocker and the brace, and the brace itself is in the way so you can't get a drill in there to cut out the spot welds. Also, you can see we have some rust on the brace that will need to be cut out and replaced.
We used a cut off wheel to slice out this wedge shaped piece of the brace so we could access the spot welds.
Here is the bottom piece of the brace coming off. We'll remake this out of some scrap metal before reattaching it to the brace. In this picture there is still a small strip of quarter-panel attached to the rocker that we need to remove. Once we did, the rocker was cleaned off with a grinder.
The last area to clean up was the wheelwell and ours was pretty hacked up. At some point, the lip was cut and rolled for extra tire clearance, which just added to the difficulty of cleaning it up. We decided that we would need to replace the outer wheelwell thanks to these cuts along and, of course, the rust.
So here is what we ordered from Auto Metal Direct, a full OE-style quarter-panel (PN 700-3570-L), outer wheelhouse (PN 770-3570-L), and a trunk floor extension (PN 840-3570-L). All the products set us back $444.85, not too shabby for what we got. The quarter is manufactured to OE specs, including thickness of metal, at the AMD facility on the company's own steel dies. Everything goes through a test fitting process before being approved for production, and all holes, contours, cut-outs, door jambs, etc., are included as original. We came to find out that the products fit great, not something you can't always say about aftermarket sheetmetal.
Here are the supporting sundries we got from Summit Racing to help us properly install all the sheetmetal. We got weld through primer (PN SUM-SP1105), All-Metal for the roof-to-quarter seam (PN UCP-14060), Rage filler to finish the seam (PN FGE-100106), sandpaper 80, 180, 220, and 320 grit rolls for a long block (PN SUM-AB514C3SRP8S, SUM-AB514C3SRP1S, SUM-AB514C3SRP2S, and SUM-AB514C3SRP3S), Cleco pliers with pin kit to temporarily hold panels (PN SUM-G1850), Seam Sealer (PN TRM-8505), locking C-Clamps (PN VTR-PR6 and PN VTR-PR18), a set of Dent Fix Equipment 5/16-inch hole punch pliers (PN DF516), and lastly 3M Automix panel bonding adhesive (PN TRM-8115), and the proper applicator gun (PN TRM-8571). All these items set us back $416.25.
Instead of replacing the entire outer wheelhouse, we are just going to use some of the new metal. We cut out just what we needed and then clamped it in place. Here our main helper for the job, Lucky Costa, is measuring the distance to make sure it's in the proper place. Once he had it in the proper position he scribed a line along the edge of the patch panel.
We used a cut off wheel to slice off the original wheelhouse. This left us a perfect butt weld line to attach the patch. We laid down a few tack welds to hold the new piece in place.
Then we test fit the trunk dropout. The angle of the patch at the back edge needed to be adjusted and these wide jaw flat pliers Lucky had made that a snap.
After a little more adjusting of the edge, we finally had the drop out fitting perfectly, so we clamped it in place so we could start fitting the quarter-panel. Since the car is up on a lift, we reinstalled the rear tire and put the car back on the ground so there will be no chassis flex messing up our fit.
The quarter-panel dropped right into place, so we clamped it along the perimeter (where we could) so Lucky could trim the top edge to mate up with our butt weld seam along the roof. We used a combination of clamps and Clecos to hold the quarter in place for the next step.
Once that was trimmed and sitting flush, we installed the deck lid and made sure there was a good gap. We used screws in the trunk jam to hold the quarter in place since the Clecos stuck up and interfered with the deck lid. Once we were sure the quarter was fitted OK, we mapped out how we were going to affix it t. We will be plug welding most of it to emulate spot-welds the factory used, but some areas will receive a different treatment. The taillight panel will be edge welded and the rocker and lower valance areas will be affixed with panel bond.
With everything fitted and marked, it was all removed so we could prepare the parts for welding. The Dent Fix Equipment 5/16-inch hole punch pliers made it a snap to make all our plug welding holes. This could have been done with a drill, but it would have taken a long time with the amount of holes needed.
Now all the bare metal areas were sealed with Summit's Weld Through metal etching primer. This should prevent rust from forming between the new panels.
It was time to fire up our little Lincoln SP-100 wire feed welder. After doing a few test welds on some of the scrap material to get the welder set up right (D on the voltage and 4.5 on the wire speed), Lucky finished welding on the wheelhouse patch, and then plug welded the trunk drop off in place through the holes we punched with the Dent Fix pliers.
Now Lucky moved forward and welded in the wedge piece of the front brace we removed earlier. As you can see, there is a putty knife sitting between the brace and the rocker. That is there because the quarter-panel actually slips in between the brace and the rocker so the knife is there to make sure we hade the proper amount of clearance to allow it in. Once all the welding was completed, all bare metal and welds were covered in primer. Now we were ready to install the quarter.
Since we don't have a fancy spot welder that can make this weld, we will be using some modern chemicals here and at the lower valance. A healthy amount of the 3M Panel Bond was applied where we just couldn't get the welder.
After application of the panel bond, we clamped the quarter back on the car and let it sit over night so the stuff could cure completely.
We came back in the next morning to start the welding procedure. To get a proper plug weld, start welding in center of the hole on the lower piece of material, don't move the welder until the hole is almost full. Then move outwards in a circular movement the weld is completed. You can also start at the outside and work our way towards the middle but if you move too fast with this technique you may not get full penetration on the lower piece.
The wheelwells use the same technique, but once Lucky started welding upside down we had to adjust the wire speed and voltage just a bit. We had to slow down the wire speed and Lucky had to weld a bit faster to make sure the molten puddle didn't drip off. Also, when welding upside down make sure to pay attention to your nozzle, it will load up with spatter very fast, and when it does your welds will get crummy.
The taillight panel is edge welded to the quarter-panel. Most of the area is easily accessed through the trunk, but we found it easier to approach the area in the corner through the marker light hole.
The last item to be welded in the trunk is this brace that welds to the trunk drop out. It lines up with the large hole in the back of the quarter, and we plug welded it in place.
The one area that took the most time and care was the roof seam. Because we are butt-welding it to the small section of leftover factory quarter, the chance of warping the material is high. To prevent this from being an issue, Lucky did a few small tacks, then cooled the area with an air hose. Then he moved over and did a few more tacks. He repeated this tack-and-cool method till the entire seam was stitched up.
Next, all the welds were cleaned up with a grinder. The ones down in the trunk gutter had to be smoothed out with a cut off wheel and some cautious grind work. One procedure we didn't get any shots of was us seam sealing all the joints. It's pretty easy to do. Apply it with a caulking gun and smooth it with a brush. Plus, we had the passenger- side still intact for examples of where to put it in case we got lost.
Now it was time to smooth out the roof seam and instead of lead we are using All-Metal for the first layer. All-Metal is an aluminum-filled, rustproof and waterproof filler that is perfect for this area. It is mixed and spread just like plastic body filler.
Once it started to kick, we came back with a shaper File Blade to quickly get the stuff somewhat smooth and close to level. After the file, we let the All-Metal cure completely before smoothing it with some 80-grit paper on a long block.
We sanded the All-Metal a little more than needed so we could use a layer of Rage filler. Once mixed, the Rage filler goes on nice and smooth, and sands rather nicely.
It took us two thin coats to get the area done, and we are very impressed with how well the Rage feathers out along the edges. We used a little guide coat before the second coat to make sure we were on the right track. We finished sanding the area with 220-grit, which leaves the proper surface for priming.
After cleaning all the areas with some pre-clean, we dusted them with some primer. That completes the job and we are pretty happy with the results—and the fact we can say, “We did it ourselves.” We can't state enough at how impressed we were with the AMD quarter-panel and its fitment. The company is proud of its product and we can see why. This job was pretty involved, so out of curiosity we called around to a few body shops to get an idea of how much a professional body shop would charge. We were given prices from $1,000 to $1,800 just in labor, so we figured we saved ourselves that much for a weekend's worth of work. That's enough savings that if we didn't have a welder we could have purchased one and still come out ahead.