Friday, April 17, 2015

Rear transition pan metal work, part 5 - priming the rear floor

1967 Ford Mustang Fastback floor pan primer Maybe this shouldn't warrant its own post, but there was a lot of work over several weekends that went into cleaning up the bottom of the trunk and transition pan area. I'll just put a lot of pics up and you can make loud angle grinder sounds while you look at them and it'll be like you're actually there.

There was a lot of surface rust down there, and I had to find out if there was any metal cancer hiding under all that. I was hoping to find clean metal under the grime, dirt, and rust, and for the most part, that's all I found.

 Drivers side rear frame rail

 Passenger side rear frame rail. Rust, and missing paint in many cases.

 Looking straight up at the transition pan bottom. All these shots are after being cleaned of most dirt and grime with Simple Green and a scrubbing pad. Simple Green seems to work as well as the heavy duty degreasers I started with. (Some people get lucky and find pristine floors after a good cleaning. Not so here.)

Passenger side trunk drop off panel 

 Drivers side trunk drop off panel. Quite rusty.

 Looking up at the drivers side trunk floor. How exactly does one strip that area?

 Looking up at the passengers side trunk floor, you can see a textured undercoating and some black paint overspray from the factory. The concours guys would try to mimic this same pattern and texture. I need smooth and uniform to be able to sleep at night.

So, all you have to do is grab your angle grinder, cordless drill, and as many wire brush/cup/wheel attachments that you can get your hands on and get after it. If I had a rotisserie, this would have been much easier on my back, but where's the fun in that?

 <Insert angle grinder noise here>

 This part was not bad - it's overhead work, but wide open and easy to reach.

 Passenger trunk floor - this was not fun. 

This is the forward leaf spring mounting perch on the passenger side. Weak metal here would be bad news, so it's got to get checked on both sides. 

Passenger trunk floor and trunk drop off.

  Drivers trunk floor - this was probably the worst part. Hard to reach, hard to see.

 Rear trunk/taillight panel support. 

 I did find a little hole in the passenger frame rail, and when I poked it with a screwdriver, it opened up quite a bit. After poking around and looking inside the rail, this appeared to be a hole caused by the traction bar rubbing against the rail, not rust. I masked it with tape and cut it out.

 The offending piece of metal.

 Patch installed and welds ground down. 

After all the wire wheeling, there's the cleaning. Then the degreasing. It has to be clean, dry metal for the primer to adhere properly. Then masked off with paper and tape.

>> Finished primed surfaces are only as good as the prep work that goes into them. Take the time needed to do the cleaning right, or you may end up doing it again.<<

Inside the car, I used SPI Red Oxide primer on the floor patching work. While the Red Oxide does look similar to the original primer I've found around the car, I tried a test patch and I don't like the color as much as I thought I would - it's too bright for me. So I ordered some SPI Black to do the bottom of the car. For the record, a car like mine built at the San Jose plant in 1967 would have most likely had the Red Oxide color. Other plants may have had a dark grey 'slop' color, where the line workers at Ford would have mixed up leftover paint and used it as primer. I know black isn't factory correct for this car, but I don't care - my car, my rules.

The SPI epoxy is good about not having too much overspray, but I work in pretty cramped quarters, so masking is necessary. Also, I needed a gun that would spray overhead. I found one at Lowes Automotive that worked great for like $20 on the clearance shelf. The Vapor gun is the blue one on the left, and the Lowes gun is the one on the right.

The cup is side-mounted and can be rotated to allow spraying pretty much straight up. While the pattern isn't quite as nice as the Vapor gun I already had, it did the job just fine. [04/02/2016 edit: looks like this gun may be discontinued as a standalone item at Lowes, so pick one up now while you can.] I used about 20 ounces of mixed primer to do two coats over this section.

The money shot...

"...And I even like the color!"

Go back and look at that first shot on this post again. I'll wait.
Yeah, cool, right?
(all the blue is from the deep blue New Mexico sky reflected in the fresh primer.)

I know no one else will really ever see this, and once the rear axle goes back in, even less of all this will be visible. But I'm glad I got this wrapped up and it's nice to know there isn't a bunch of rust hiding under here.

Rear transition pan metal work, part 4 - dual exhaust reinforcement plates priming and installation

1967 Ford Mustang Fastback dual exhaust reinforcement pan installation
While my car had dual exhaust when I got it, I don't think it was installed properly. It was just attached to the floorpan in this area by a few large lag screws. Non-ideal solution, if you ask me. The exhaust is suspended from several points at the back of the car from rubber hangers that should be hard-mounted to the car. Lag screws though 19 gauge metal don't do much except tear up the metal and poke your passengers in the posterior if the bumps are big enough.

The pans come as uncoated metal that need a good cleaning. Child labor to the rescue! Wire brush attachment on a cordless drill is fine here.

The Apprentice is starting to suspect more 'character-building' is happening... 

The pans clean up nicely. Ready for clean/degrease and priming.

Using the same SPI Red Oxide primer, I shot them front and back and let them cure for a day or so. I left some spots blank (the orange stickers) on the pans and in corresponding places on the floor pan so I could just peel them off after priming and weld the pans in place. You can't weld through cured epoxy primer (well, I can't anyway).

If you look close, you see one of them has the big hole for the seat belt bracket bolt hogged out. I failed to make a proper measurement when I welded the bracket onto the floor pan. Oops. The smaller diagonal row of three holes is where the exhaust hanger support bracket is installed. In any case, the reinforcement pan will now fit well with the corresponding holes in the floor.

Now there is primer on all surfaces here - the floor and the both sides of these pans - so there will be no rusting due to trapped moisture later on. Six plug welds in each hold them to the floor. All this will get another coating of primer later, so this is where we stop for now.

I love the before-after comparison. 

This area is now stronger, cleaner, and more correct than it was before. This little transformation took me on-again/off-again nights and weekends over the course of three months. 

Next up is the cleaning, stripping, and priming of the bottom of the transition pan and trunk area.

Rear transition pan metal work, part 3 - repairing the shock mounts and rear seat bracket

1967 Ford Mustang Fastback rear shock mount repairs Here's where we left off - the bottom of the floorpan in this area is mostly done. There are some welds to clean up and some dents to hammer out to get the exhaust reinforcements to fit, but the end is in sight.

I cleaned the whole shock mounting area down to bare metal with the wire wheel on an angle grinder, The shock mount hole on the drivers side is ok - no cracks there.

Several cracks on the passenger side - again, due to the air shocks, this mounting hole was bearing too much load from the weight of the car. Forgot to take pics of the 'before' again (grrr....). Drill the end of the crack and start welding from the stop-drill hole to the shock mount hole. The inside gets the same treatment.

Here's the inside at this point. You can also see the dual exhaust reinforcement plates being test fit - more on that later.

This is on the passenger side. The bracket at the shock mount access hole is to hold the lower seat cushion in place. It appears to be in the wrong place after an 'attempt' to braze it back in place at some point.

I removed the bracket and couldn't help but notice a bunch of holes and cracks in the transition pan. It was so bad the bracket was barely hanging on there. So, gotta fill those too...

Cleaned up the bracket - I also drilled a couple holes in where those dimples are so I could plug weld the bracket in place in addition to a few edge welds. They say beginning welders overdo everything...

Where the brazing was still good, I left it alone. I don't think MIG weld material likes brass. So the drivers side is pretty much untouched as the repairs were still solid and there weren't any cracks at the shock mount points.

After fixing all this, I removed my welders ground point, filled lots of little holes and then cleaned/degreased the surfaces and masked it all off so I could prime it. I used a bona-fide 2-part epoxy primer from SPI (link at right) in a Red Oxide color that is supposed to be similar to what the Ford factory would have used back in the 60's. I'll provide more details on priming in a later post.

Here's the finished top side. I'm much happier with this area now. And yes, it's supposed to be that color. It takes a couple days to cure, and it's not as glossy after that.

Next up, I'll bring in 'reinforcements'!