Tuesday, September 7, 2010

The Deck Lid from Hell

 Waaaayyyy back in October, I had the car media blasted including the deck lid.  Well, as you may also recall, I had some "concerns" regarding the quality of the deck lid. To be honest, my concerns with the deck lid have been giving me pause these past few months. I simply haven't wanted to deal with it as I knew it would either cost me more time or money, neither of which I've been wanting to give up for the past couple of months what with summer constantly pestering me with it's beautiful, warm, sunny days and constantly hounding me to do something other than sweat it out in a hot garage. Well, like all good things, the days of summer have gone and the day of reckoning has come.

So there I was, back where I had started, pondering the fate of the deck lid. I could just forgo the steel deck and buy a fiberglass Shelby style deck lid. Well, that would mean that I would also need the matching quarter extensions and as long as I had gone to the trouble of doing THAT, I would also go ahead and buy the Shelby style tail panel and lights. As appealing as that all is, it's just not in the current budget and I would not be happy just getting the deck lid without the tail panel/lights. Another option would have been to buy a repro deck lid. I did some research on the various Mustang forums and the consensus was that the repro deck lids are a crap shoot for fitment and quality. I could also buy a used original deck lid but the chances of getting the same as I already have are pretty high after it's been media blasted. So, I had already had mine blasted and if I were to buy anything, it would eventually be replaced by a full Shelby style back end so that would be money out the window. I think you can see where this is going by now. The only true option left to me was to fix that which I already had. If I screwed up too badly, I could still go the other routes and not be out much other than time and some supplies.

So, first things first. The top of the lid was in serious need of attention but nothing is easy in an old rusty car like Ol' Rusty as the rear inside edge was as holey as the Pope:

I started by grinding away the surface rust with a knotted wire wheel. The wire wheel also does a good job of chewing through the thin sheet metal and exposing places where rust had just almost eaten through the metal from the inside. I then set to cutting away the rusted metal and making and welding in patches of new 20ga metal like I did for the corner as seen here.

And again along the center:

I then ground down the welds and did a lot of pinhole filling and more grinding until the area was generally level:

I then treated the area with Ospho to stabilize the remaining surface rust. During this phase I also poured Ospho inside the reinforcement braces and sloshed it around to stabilize the rust inside the deck lid as well:

Body filler was then applied to the repaired areas and sanded:

Finally, the underside of the deck lid could be primered with DP40LF:

Well, I'd like to say that's all there was to it but that was only HALF the job!  I ran a 17 inch sanding board over the top of the lid with 46 grit paper just to see what I was dealing with and this was the answer... holy crap!  I honestly considered bailing on the project at this point but  instead, as the Brits say, I put on a stiff upper lip and set to work.  I might also mention here that to this point I'd never worked with body filler to this extent so this whole thing was going to be a learning experience.  I don't know if this particular task was the best learning experience for a newbie but let's just chalk it up to "trial by fire".

First I ran 80 grit with a disk sander over the lid to give the filler something to "bite" onto:

This is the filler I used.  I didn't choose it for any particular reason other than it was on sale at the paint/body supply shop I go to.  I think Evercoat RAGE is the filler of choice.

The mixing directions said to lay down a line of hardener across the diameter of a 4" puddle of filler.  It might have been too much hardener for the 80 degree day that I did this on because it set up FAST.  I must have lost at least half of the first 2 or 3 batches I mixed before I figured out that I needed to reduce the hardener a bit.

This is the color after mixing.  A consistent blue.

I laid the first coat down pretty heavy (about 1/16th - 1/8th inch).

Before the filler fully hardened, I was able to go over it with a cheese grater type of file.  After it hardened, I went to work in a cross-hatch pattern with a 17" sanding board and 46 grit paper while keeping the board parallel to the front and back edges of the lid.   I knew I was "done" when metal started peeking through the filler.

I then layed down a second, thinner coat.

And sanded that down with the same 17" sanding board with 46 grit paper.   I'm not sure how I figured that the deck lid was smooth and level other than the sanding board was cutting consistently across the whole surface with no low spots (or very shallow low spots) because there were 46 grit scratches across the entire surface:

I then decided to use a guide coat to see how close I was.  Just a black spray paint I had laying around:

Sand that away and see what black spots remain.  Hmm... maybe it wasn't so level after all:

I had read about people doing a layer of regular polyester filler, sanding that and then filling the scratches and finishing leveling with a polyester glazing putty.  So, I went down to NAPA and picked their least expensive two-part putty.  $18 a tube:

For that one it was a 1.5" long strip of hardener to a 4" puddle:

First I filled the low spots as indicated by the guide coat.  Put putty where the black spots are:

I sanded it level with the 46 grit board again and then applied a layer of glazing putty over the entire surface to fill in the 46 grit scratches and to level up any remaining low spots and wet sanded it with 220 grit.  Just a side note on the experience of wet sanding such a large surface, there was some suction!  I lost grip on the block several because the sanding block would just stop.  Pretty soon I learned to do slower strokes and just let the suction help and keep the block flat against the surface.  (NOTE: I found out later that it is bad to wet sand filler as it can absorb moisture and cause problems with paint later).

In no time, the top of the deck lid was smooth as a baby's butt and I couldn't feel any low/high/rough spots over the surface so I deemed it ready for primer:

This is the pile of material I had sanded off the deck lid next to my Harbor Freight 17" sanding board.  Speaking of this board, when I was sanding my first coat of filler with it, I noticed that there were gouges being ground into the filler with each stroke of the board.  I examined the paper thinking it was a loaded spot but there was nothing there.  Then I noticed that the paper was bulged in middle... WTF?  Upon closer inspection, I had discovered that nearly all of the (rather tiny) wood screws holding the handle to the board had ripped out!  After I replaced them with #10 1" wood screws, I didn't have the problem again.   So, watch out if you buy one of these:

Again, I employed the ubiquitous engine hoist to support the deck lid for primer:

Here's the first coat of primer.  Besides being inconsistent from my spraying all the primer I had in the gun until empty resulting in the random dry spots, I also noticed a few spots where the 46 grit scratches hadn't been filled and a couple of poorly sanded spots:

So, I sanded the questionable areas with 80 grit and then applied some glazing putty to fill the scratches and resulting low spots and then wet sanded the whole deck lid again with 220:

I applied the DP40LF again but am much happier with the results.  I think I'll call this good for now:

I needed a place to keep my fresh deck lid so I media blasted the clips and painted them and put them back in the lid and bolted it back on the car!

It's not perfect.  Not a show-car quality job by any means but it's good-nuff for this car until I can get a Shelby rear-end on her and anyway, I learned a lot more about body filler than I knew when I started.  I think a pro would have hammered the high spots (bare metal exposed after sanding the filler) down to ensure a perfectly level surface but because of the extent of the damage to the top of the deck lid, I was afraid that pounding down on one spot would raise up another or just generally cause more problems forcing me to remove the filler and start over and frankly, this deck lid doesn't mean THAT much to me to do this again.


  1. A long awaited update to your "main project", Alex ! Please explain, why not apply a coat of epoxy primer prior to body filler ?

  2. Ripa, I've read that many pros apply to epoxy primer on a regular basis while others will only apply to bare metal. So, I'm not sure of the firm adherence of polyester filler to an epoxy based primer. Will it fall out in a few years or grab on just fine? I don't know but I'm thinking that I'll grind away the epoxy primer when I get to the point of body-filling the various patches on my fenders, cowl, etc. just for good measure. It should be short work with a knotted wire wheel and flap disk to get down to the metal again. I won't be stressing about getting ALL the primer out of the nooks and crannies though.

  3. Hi Alex, I had a practice on a 65 trunk lid earlier this year. It had been crinkled across the left side and someone had just decided to pack it full of bondo and level it off. They had tried to do some sort of panel beating but it really was very very bad. I know what you mean about doing all the sanding, trying to find the high spots and refilling the lows and letting it dry again, sand again blah blah... I ended up getting a near perfect second hand one whilst I was in Hawaii and shipped it with the car at the time so hopefully there should be next to nothing to do with it other than rub it back and paint it. There was no way I was going to tackle repairing the existing one as you can image with the salty Hawaiian air it was completely flogged out across the back and just about fell apart in my hands each time I tried lifting the trunklid, oh yeah, not to mention the rust around the hinge mounts!!! Great job you've done there...

  4. Thanks Mike. Yeah, it's not like replacement deck lids are all that expensive, it's just that I'm going to eventually do the Shelby thing and am going to need all new fiberglass parts anyway so nothing to lose by going cheap in this particular instance. I think if it was even a fraction worse than it is, I'd have just junked it.

  5. In relation to Ripa's question about applying filler over epoxy primer, I found this web page that might give more insight: http://www.autobodystore.com/filler_&_epoxy.shtml It appears that the epoxy to metal bond may be weaker than the filler to metal bond. However, it's hard to say if the guy that did the tests waited long enough for the epoxy primer to fully harden or if he prepped the surface for the primer correctly.

  6. I feel really happy to have seen your webpage and look forward to so many more entertaining times reading here. Same as your blog I found another one Sohman Epoxy
    . Actually, I was looking for the same information on the internet forSohman Epoxy
    and came across your blog. I am impressed by the information that you have on this blog. Thanks once more for designs.