Sunday, February 26, 2017

How to assess rust damage on a quarter panel

No posts in a while, I know. I've been busy with a few non-Mustang projects lately, and this next fix is a biggie - so instead of doing it all in one post, I'll have to break it into a few. Hopefully, this means more frequent posts as well.

I could just as easily call this post "How to face your demons", as I've been dreading this work since I bought the car. Yep, that's right, I knew this car had visible rust on the body and I bought it anyway. I like to think that speaks to my optimism and ruthless persistence -but it could just as easily be a prime example of bad decision making. Either way, I'm about to find out.

Let me orient the reader for this topic. The quarter panel, above, is the expanse of metal that forms the back of the car from the tail panel to the door latch panel. It includes the decorative vent mountings, and forms the edges of the trunk, door, and wheel arch. On the fastbacks, it goes all the way up to the roof line and includes the 'sail' with the fresh air vent. It's huge.

The right side quarter panel had a little hole at the top of the wheel arch, and the half-inch hole went all the way through - not quite big enough to put a finger through. What may not be immediately obvious is that there's actually two pieces of metal here - the quarter panel and the (outer) wheelhouse. The wheelhouse is the big curved dome that the wheel rides in and keeps water and mud out of the car. The quarter panel is spot welded to the wheelhouse where the outer edges meet at the wheel opening.

So, as the title suggests, I'm going to show what I was looking at to figure out how bad the rust really is. I'm trying to avoid cutting more metal off the car than is required to make a good repair*. The quarter panel has lots of curved surfaces and those where the rust and curves are will actually dictate how I decide to patch this part.

*A more experienced person wouldn't have to do this. I'll remind you again I'm not that person.

The easiest area to look for damage is back in the trunk behind the wheel. In this shot, the back of the wheelwell is at the left, and the outer skin of the car is at top. When I went looking, I found nasty looking metal, but it passed the "stab it with something sharp" test, at least where I could reach. But the metal looks like it could be weak and pitted at the edges. Ick.

Next up, I can look behind the interior trim panels and see what the quarter skin looks like at the forward section. Here's the passenger side rear interior trim panel before I took it out (many moons ago...)

I found a monster of a mouse nest behind the trim panel. This is bad, as all this material would be really likely to hold moisture and cause rust from inside the car...

...which is exactly what seems to have happened here. The skin of the quarter is rusted at the wheel well and the rocker panel junctions. So that's a bummer.

When subjected to stabbing test, I found one actual hole an some weak metal that deformed quite a bit. Another bummer.

I then picked out and broke off all the rust nuggets I could by hand, and then hit the outside of the wheel arch with a stripping disc to see what would come off. That half-inch hole became a a 6" x 3" gash through the quarter skin an the outer wheel house. Yikes. Well, just remember, if you can see the rust, it's usually a lot worse under the surface.

Now let's look inside the wheel well. Sticking my head where the wheel usually goes and looking aft, I see outer wheel house is soaked in something oily and has rust at the bottom where it meets the trunk drop-off and the quarter panel. It takes a lot of light and some scraping, but it's there nonetheless.

Looking up at the top of the wheel opening (see the hole?) there is a rust stain that runs the entire length of the outer wheel house from front to back. That's likely a serious bummer as well, as it means that most of the outer wheel house is rusted and will need replacing as well as some part of the quarter panel.

Looking closely at the hole in the top of the wheel arch, the rust seems to extend a good inch up from the edge of the hole in at least two directions.

I decided to cut half of the outer wheelhouse away from the car so I could actually see the extent of the rust on the inside of the quarter panel. After drilling all the spot welds holding the quarter panel to the outer wheelhouse, I marked my line with tape and cut it out. There are also a couple spot welds at the wheelhouse/rocker panel junction.

Stupid sideways pics.

Here's a view from inside the trunk looking forward once the wheelhouse portion was cut out. What's left is just the quarter panel. Notice here the wheel lip on the quarter panel is rusty. It looks worse in person.

Here's one of the pieces of the wheelhouse I cut out. The edge that was connected to the quarter panel is totally shot - it's weak and perforated. Remember, all I could see before I cut this out was the stain in the wheel opening. This is the opposite side of that same piece of metal.

The other part of the wheelhouse was in just as bad a shape. No point in trying to weld to this mess.

Oh, and a bonus - another mouse nest, this time inside the rocker panel. I was going to clean this space out anyways, but now I have to do it while wearing a respirator.

Looking from the inside, the rest of the lip on the quarter panel is just as bad. Again, no point in welding on that mess.

Here's a great view of the rust that is on the quarter skin from the big mouse nest. That metal is weaker than it looks. It has to be replaced as well.

Remember the original half-inch rust hole that we started with? Look how bad it looks from the backside. "You're going to need a bigger patch."

So now that I know where all the rust and weak metal areas are, I marked them all out all the on the front of the panel to assess how much metal had to be replaced.

So, I have a good idea of what's bad and needs to be replaced. And I have a replacement part ready to go. That's actually a replacement panel for a coupe, not a fastback, and that's on purpose.

Stay tuned for the next step - cutting.

Saturday, November 5, 2016

All caught up, and still more to do. (And a clip show!)

The last post on the cowl clean-up job was the last "historical" post I had. Historical, in this sense, as in "the past", not "joining the canon of Great American Literature, soon to be required reading for incoming freshmen".

Up till now, I've been doing new projects and blogging the old projects. The old projects are almost in the same order I actually did them, but if they're out of order, I note that in the post.  So if you're asking "what's the order to restore an old Mustang?", you're seeing an answer here. Maybe not the right answer, but it's how I'm doing it. 

Now I'm out of old work to post up here. Any new posts will be essentially live, as-it-happens. Which means I'll start posting not just the work in the garage, but research results, parts selection, and other background material.

The car was purchased in September 2011, and work started in January 2012. So, we're coming up on 5 years on this project. Projecting out at my current rate of progress, I expect to be done in 2019, give or take 2 years. So, back to work.

Sept 2011

June 2013

Sept 2013

July 2014 
Oct 2014

Jan 2012

Mar 2013

Sept 2014

Nov 2014

Jan 2015

June 2015

Aug 2015

April 2016

Mar 2016

Mar 2016

May 2016

Jun 2016

Aug 2016

Oct 2016

Nov 2016

And the beat goes on...

Sunday, October 30, 2016

Cowl Inspection and Cleaning

How about a little history on the long-term effects of cost-cutting at the factory?

The cowl assembly on these old Mustangs is a known trouble spot. Ford didn't do much in the way of corrosion protection, nor did they design the cowl to allow easy access for cleaning after the car left the factory.

Cowl at far left - the thing with vents in it.

Over time, the cowl would fill up with leaves, pine needles, and other debris while the car sat parked outside under trees.  In many cases, mice would build nests in the cowl of cars waiting to be restored "some day". Rain water would get in there, quietly and invisibly soaking the stuff in the cowl, and eventually cause the cowl metal to rot away. The rotted cowl now allows the same water to get into the car and start rotting away the floors.

Instead of a well primed, sealed and painted cowl from day one, you get to replace floors and other metal decades later. Or not, depending on how lucky you are with your particular car.

My car needed a small patch on the passenger side toe-board. I was worried this meant my cowl was rotted out and would need to be replaced. The cowl is a two-piece affair, top and bottom, held together by a gazillion (~200) spot welds and locates the base of the windshield, the export brace, and centers the rear of the fenders. It's visible and it's structural, so it's pretty important to make sure it's in good shape.

First thing I did was determine how bad my particular nightmare was. Once the fenders were off the car I used compressed air to blow out the cowl and fished around with a hanger to pull big bits of junk out though the drain holes on the ends of the cowl.

Pile of crap blown out of the passengers side cowl drain.

Drivers' side cowl junk blown out.

Once the dry stuff is out, the next step is to run water through the cowl vents on top and look for water coming inside the car. Passing means no water comes in the car at all. Failing means any water is visible in the car. That means the lower cowl is rotted and new metal is needed. There's several quick-'n-dirty fixes I've seen online, but the best and most effective way to treat this is new metal.

Looking for water under the dash at the Driver's side air vent (that hole at top is the fresh air intake from the cowl.)

The passenger side cowl vent feeds the heater or the A/C box. Typically the vents are what rot away first due to wet debris in the cowl box.

I had no water intrusion when I hosed out the cowl. Finally, a win. 

But I couldn't just leave it alone. I had no idea if the cowl is pristine or rotting away and and will leak the next time it rains. I had to at least open the ends and inspect the condition of the 'hats' inside the cowl. Once inside, I assessed the condition of the metal (still strong) and then cleaned, sealed, and painted the cowl ends to ensure I get another 50 years of service out if the cowl.

This is where I started - the passenger side cowl end.

The cowl/apron brace had already been removed, so I just had to strip the paint and seam sealer away. I used a cutting wheel to cut the cowl end open, but I left the back connected to make a 'sardine can' lid I could easily re-weld later. This turned out to be harder than I thought.

Open the lid and behold! Good metal!

Wire-wheeled and painted with rust reformer. Edges are taped so paint won't contaminate the welds later.

Seam sealer applied after the paint dries. Don't make a dam out of the seam sealer - leave a good clear path for water to get through once this is all done. 

Painted over the seam sealer and rust converter with a quality rattle can paint. I decided against epoxy because this was easier to get in and around. Not shown is the seam sealer and paint applied on the other side of the cowl hat from inside the car on my back. There are no pics of that work since I can't actually see what I'm doing. I'm sure it came out great, though...

I welded this up as best I could, but there are a few things working against me here. First, the cutting wheel made cuts that were too wide, leaving a large gap to fill with weld. I used a backing strip to close the gap. This added a lot of time and trouble to the job. The other issue is that the cowl  top is galvanized steel, which needs to be stripped off as much as possible before welding as the galvanic coating will turn into toxic fumes when it burns. So welding is done with a respirator, which is harder (for me anyway). Seriously, non-optional - don't die, just wear a respirator.

My new cowl/apron brace that came with my new frame rail assembly is all prepped and ready for installation. I just left the e-coat on it for now.

Cowl/Apron brace welded on per factory W&S manual. This side is pretty much done; I'm not going to worry about cleaning up that last weld line - its not worth the risk of making new holes, so epoxy an seam sealer will  protect it later.

Drivers side, much like the first, with lessons-learned. Drill off the cowl/apron brace...

Notice the rust under here. Nothing from the factory was used to protect this metal.

Stripped and marked my cuts. This time, I was going to cut the whole piece off, not do the sardine-can cut. And I had a new tool for just such a job:

The Communist Freight Air Saw. For the cost of an Andrew Jackson, I had a way to make smaller, cleaner cuts than the cutting wheel I used on the other side.

Nice comparison shot of the two types of cutting. The gap on the right is the cutting wheel making a slot for the air saw, which is the rest of the cut. See how much cleaner and smaller that air saw cut is?

Blamo - cowl end cut off. The lower cowl metal passes the rot-test (stab it with a punch and see if it goes through), so it gets cleaned, sealed, and painted like the other side.

"Cleaned" is sort of a relative term here. But it's better.

Rust converter paint all around. Again, the inside is perfect, but I can't see it to prove it. ;)

Seam sealer applied. Same brand (NAPA), just white this time. Remember, clear water egress is vital!

Painted with a rattle-bomb. Should last till 2067.

This side was much easier to weld up since I could place the cap back on the cowl and close up the gap as tight as I wanted to, butt-weld the top, and redo the spot welds on the edges. For future reference, this is the way to do it.

Old cowl/apron brace was blasted, painted, and hammered back into shape for installation. Weld-though primer was used on the top of the rear apron for rust protection.

Welded on, cleaned up and ready for service. I'll get some epoxy primer on and around all this next time I mix some up.

I got lucky - my cowl was in remarkably good shape. For a lot of folks, the cowl is a bucket of spiders - no fun to open up and tough to deal with once it's open. There's still seam sealing and priming, but now I'm ready to move onto the next little job.

The next little job - the rusty quarter panel.