Tips for perfect fitment of aftermarket panels
From Unique Cars #304, Oct/Nov 2009
There’s a widely held view that aftermarket panels for classic cars don’t fit properly and it’s absolutely true – they don’t. What’s more, they never will. The thing is, it’s fairly unreasonable to expect that they should.
As Leo Banks, former owner of the Muscle car Factory points out, “Not even the original panels from the factory fitted that well”. He then proceeded to point out some very noticeable irregularities in the gaps in an original metal Mustang from a very prestigious restoration shop in America.
Neither original nor aftermarket panels are going to fit no matter where they’re from, so you might as well learn what to do about it. Leo and team agreed to show us a couple of neat tricks they use to get aftermarket panels onto a car and looking good.
Although the working shots are of a Camaro, the techniques described apply to any car, like this Mustang (above). Going to the trouble shown here will put you on the path to perfect alignment
We’ve heard people question the idea of replacing original panels with aftermarket versions. Why would you do it when original Mustangs, Camaros and the like can be bought in good condition for less than it would cost in parts and labour to re-skin a car?
Leo’s answer is simple: “When you buy an original car you have no idea what’s been done to it.”
| Read next: How to fit aftermarket seats to an early Mustang
People are reluctant to remove all the original factory panels for fear of damaging them. So they simply get at as much of the structure as they can without removing everything.
But the fact is that any point at which factory metal is sandwiched together or just can’t be reached, is almost certainly going to have rust.
Leo pointed out that classic cars straight out of the factory often weren’t prepared all that well and that virtually all have underlying rust. The only way to get rid of it is to pull off the original panels and treat everything. That done, you know exactly what you’ve got.
And when all panels are replaced with properly prepared new ones, they won’t develop rust and will virtually last forever. Your children can pass it on to their children…
Fitting a full set of panels to a car is a big job and we can’t cover all of it in one article. Fitting doors, for instance, is a big subject on its own. Here, we’ll concentrate on the rear-end and roof.
We’ve used a Camaro to demonstrate but the same techniques hold true for any car for which replacement panels are available.
One big difference between the way Leo and the guys do things and the way you should tackle a job like this at home is in the number of panels removed.
In these shots all the panels are off the car. Don’t do this. The panels contribute a good deal of strength to the car, and once they’re off, the underlying structure of the car can flex to an enormous degree.
In this case, experience and equipment allow the work to be done with all panels removed but in a home garage situation it would be best to remove and replace the panels one by one, although sometimes other panels have to be removed to get at the one you want.
STEP-BY-STEP
1. Stripping all the panels from a car allows detailed preparation of the underlying metal to a much greater degree than work from the factory.
2. It’s best to start with the quarter panels. Of course, to get the originals off you’ll have to remove the roof first. It’s best to remove panels by grinding the factory spot welds out of the panel until you reach the underlying metal. That way you don’t end up with a string of holes that don’t line up and which weaken the structure.
3. Leo and the team spot weld the panels in place. Unless you happen to have a spot welder you’d be puddle welding them in place using a MIG welder. To do this, a small hole is drilled in the panel exposing the underlying metal and two layers are welded together through it. All areas to be welded should be bare metal and then covered with a weld compatible primer.
4. The outer wheel well and rear of the sill panel determine where the quarter panel is going to sit. If the outer wheel well isn’t damaged, it’s a good guide. It’s best to have the weight of the car on the axles when fitting panels so axle stands should be used.
5. Obviously, the quarters also have to line up with the doors. Yours should still be in place when fitting the quarters but if they’re not, fit them. When removing them, remember to mark the positions of the hinges with a paint marker. This makes refitting much easier.
6. You can see that the quarter panel finds its position on the wheel well, sill and behind the door. When the position looks about right Tek screws are used to hold it in position.
7. Fixing panels temporarily using Tek screws is beneficial as these hold panels very securely, can be undone and repositioned and have enough strength to actually pull panels into place. Masking tape is excellent for making sure things line up.
8. The wheel wells won’t line up with the wheel arches absolutely perfectly so you’ll have to tap the outer edge of the wheel well out to meet the wheel arch.
9. The deck lid filler panel is a good reference point. and it’s a good idea to leave the original in place. However, a new one will have to be fitted at some time. George measures the distance from the roof at both ends. Measuring is vital; measure from as many reference points as possible.
10. Here’s the sort of problem you’re going to get when fitting aftermarket panels. The filler panel sits high compared with the quarter panel and the folded edges simply don’t match and won’t sit flush.
11. One very important technique you’ll have to learn to do work like this successfully, is to make adjustment cuts. If a section of panel needs to cover a greater distance you simply slit it using a small cut-off wheel as shown.
12. Note the split section. It’s spread and tapped down into place using a particular panel hammer but you can use whatever works. A selection of quick action clamps is also essential for panel fitting work.
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13. The spread section has been filled with weld and ground back to match the profile of the rest of the area. Again, note that the panel is held in place temporarily with a self-tapping screw. This technique is one of the most important you’ll use.
14. With the transverse upper-rear fill panel added, the boot lid is set in place to check fit. As you can see there were some problems. The rear ends of the quarter panels had to come much closer together.
15. A very handy way to pull panels closer when considerable force is needed is to use a turn buckle, as shown. Attachment tabs for each end of the chain are welded to inconspicuous sections of the panel. Note the use of trammel points to measure the diagonals, which must be the same or something is wrong.
16. By the time the gap was right against the rear transverse panel, the boot section of the guard had come over so far that it had to be cut at where Borge is pointing. Note the high point down low on the quarter below the right finger.
17. Borge makes cuts to the bottom of the quarter to match the crease lines to the lower transverse fill panel. This was only a minor mis-match and won’t be seen because it’s under the bumper.
18. The alignment cuts before and after welding. The finished result still needs a little trim for the gap to run straight. You have to be prepared to cut, bend and hit your new panels to make them fit; there’s no other way.
19. Eventually, a large portion of the boot lip section of the right quarter panel had to be slit on the vertical face, moved outboard (while the panel itself stayed where it was) and stitched back together.
20. The boot lid is sitting a bit low because there’s no rubber in it but the gaps are finally right. It took a lot of work and you can see where the edges have been ground back, welded and filled. For a perfect fit, it’s the only way.
21. Small sections of original metal on the windscreen pillar interfered with a trial fit of the new roof. The answer? Cut them off! Note the new upper dash panel. Leo says that instead of complaining about fit, we should be grateful that panels like this are available new.
22. Padding is required under a roof skin but it can’t be glued in place using lashings of glue because it will shrink as it dries. Just a few dabs to hold it in place is sufficient. Strips of padding are also stuck to the underside of the skin in corresponding positions to stop vibrational noise when driving.
23. The remainder of the original roof skin should have been removed during preparation. The edges of the roof should spring into the gutter under thumb pressure. If the edge of the new skin hits the bottom of the gutter and won’t allow the skin to drop into place you know what to do; trim it!
24. Here are all the cuts and trims needed to get the roof sitting perfectly before they were cleaned up.
We asked George if he’d ever seen a panel drop into place perfectly with no adjustment. He said he once saw a door that did. That’s it! Everything else he’s ever seen has needed some sort of work for a perfect fit.
