Saturday, September 23, 2017

Installing the new Outer Wheelhouse

With the new trunk drop off in place, I'm ready to get the new outer wheelhouse put in. While I show here a fairly straightforward process, in reality I had the wheelhouse in and out of the car at least a dozen times for fit checks, both with and without the quarter panel skin. I was trying hard to not weld in a mistake.

The test fits showed one issue right off the bat - the outer wheelhouse pushed the new trunk drop off panel too far inboard when it was clamped in place. Pulling the trunk drop off to the right place would then push the wheelhouse too far out and it would then interfere with the quarter panel skin. The trunk drop off is located correctly based on the measurements from the old piece before it came off the car. So the reproduction wheelhouse will need to be modified to fit.

The bottom of the wheelhouse pushes the trunk drop off too far inboard. This rear flange on the wheelhouse needs to be modified to be pulled in a bit.

I marked a diagonal scribe line to take about 3/4" out of the flange at the bottom, but leaving the top of the flange in about the same place.

Cut and rewelded the flange in its new position. Test fitting showed it no longer deforms the trunk drop off panel. I cleaned up the welds a bit, but this entire edge will also get covered in seam sealer and it sits out of sight in the trunk well.

I prepped the wheelhouse for epoxy primer by scuffing with a red scotchbrite. I also punched all the holes in the upper flange for plug welding to the inner wheelhouse still in the car. Holes are spaced at about 1 inch intervals. 

Two coats of primer on both sides. Better than the E-coating it came with.

I also primed the inner structure and the new drop off panel.

Test fitting the outer wheelhouse. In preparation for welding, I cleaned the epoxy around the holes I punched, and once I was happy with the fit, I scribed the location of the new holes on the inner wheelhouse flange so I could clean those spots as well.

Prepping the inner wheelhouse weld locations. The factory put the inner and outer wheelhouses together by using a rolling seam weld around the whole perimeter of the pieces. Great for a tight, continuous joint, bu this makes it hard to take them apart, plus it's a type of weld that a home hobbiest is probably not going to be able to replicate. So I'm going to use plug welds. But a long string of plug welds will not be nearly as watertight as the seam weld was, so I'll need to run a good bead of seam sealer in the gap inside the finished wheelwell assembly.

New part clamped in and lined up. 

I placed the skin over the clamped wheelwell to make sure it fits well enough.

Most of the stuff I find online about replacing this part is from coupes, not fastbacks, which have a different inner structure, so I'm kind of making this part up as I go. When I removed the old wheelhouse, I drilled all the way through the structural brace that holds the wheelhouse in place.The new outer wheelhouse slides in between the inner wheelhouse and the brace. This way I just plug weld the brace to the outer wheelhouse from the outside, and from the inside I weld the outer wheelhouse to the inner one. Plug welds all around. There are a lot of them, so it took a while to prevent warping.

Five welds at the newly-relocated rear flange. After I clean the welds up, this will also get a bead of seam sealer. The trunk drop off is right where it's supposed to be, so that's good. 

Here's the inner brace welds for the wheelhouse. I cleaned up the welds a little and brushed some epoxy on them as well.

Seam sealer applied to the trunk drop off weld line and the lightly modified rear flange on the wheelhouse.

Per the weld and sealant manual, there is some sealer at the front of the wheelhouse where it meets the rocker panel.

Touch up primer all around

With the trunk drop off and outer wheelhouse replaced, its time to get to the Quarter Panel Skin. With any luck, I won't screw it up.

Saturday, August 12, 2017

How to replace the trunk drop-off panel using a butt-weld

It's easy! Just cut off the old panel and fit up the new one. Set the welder to 11 and go for it! No, not really. But it's fairly straightforward. There was plenty of evidence that there would be some rotten metal in this area from day one, so this was not a surprise to me at all.

Before the project began - this is inside the trunk looking into the passenger side trunk well.

I could better view of the trunk area once I cut out the quarter panel skin. I'd primed all this metal when I did the trunk, but I kinda figured I'd be in there again later on.

This is the trunk drop-off. It's actually part of the trunk floor panel on this side, but because it sits behind the wheel well and stuff tends to either accumulate in here or road salt eats it from the outside, the metal is subject to rot. Once it was fully exposed, I used a wire wheel on my grinder to see how much of the metal was bad. The outside, exposed to the elements was fine. But the interior-facing side shown here was pocked with rust and weak spots all over, especially at the edges where the new quarter needs to be welded on. So it has to be replaced.

I lined up the replacement panel on the old panel just to see how close it was to original specs and screwed it into the old panel, as some folks have suggested you line up panels that are going to be butt-welded. Because I'm considering a butt-weld for the quarter skin, this was a chance to try the technique. I scribed a line for my cut and clamped the ends to keep the thing stable while cutting.

Closeup of the cut-line.

I used a whiz wheel on a die grinder to cut through both pieces. I'm not convinced this was a better way to cut metal. If I were to do it again, I'd use a jigsaw.

Removing the panel exposes the open space behind the trunk crossmember. There are three spot welds back here to remove in order to get the trunk drop-off removed. This area gets nasty due to road grit getting kicked up here, thus the rust in between panels.

Cleaned up and ready for primer and welding.

The replacement is sold as a fit for 65-70 model year cars. But all that means is that everyone has to do some mods to make it fit their application. In my case for a 1967 car, the lower and rear edges are too long and there is an extra hole that will need to be filled or plugged. Also the forward drain hole isn't in place, so I'll have to add that. I won't trim it till the quarter is in place.

Lining up the new panel on the old. I used magnets and clamps, and kept the gap as tight as I could. In most places the gap was smaller than my weld wire diameter (0.030"). I've tried the little screw clamps everyone talks about and found that they leave too large a gap for my clumsy welding skills.

The backside of the trunk was stripped of primer as well - remember, 'surgically clean metal' is the rule here.

Many small tacks later, it's in. I only needed the copper spoon for a few of the tacks where my gap was too large. I tried planishing the welds as well. but the space it really tight, so that didn't work as well as I'd hoped.

Ground down the welds and scuffed the whole panel in prep for priming.

Admittedly, that does look better, and I like that the metal is fresh and solid. 

Here's the three plug welds on the crossmember that need to be redone. Clean, clamp, and burn.

Not the prettiest welds, but good penetration and no one will see these.

Two coats of SPI black epoxy primer were applied on both sides.

The gloss level is high since I had just sprayed this when I took the picture. It'll flatten out as the week goes on and look like the rest of the floor before long. But now we have new good metal for welding a new quarter panel skin onto.

On to the next step - installing the new outer wheel well.

Sunday, July 9, 2017

And...we're back! Cleaning up the edges and test fitting the rear wheelwell.

I got the garage back last week, so after a few months off I'm ready to get back at the Mustang again. I still don't know how to install a quarter panel, but it's time to keep plugging along anyway.

Now that the quarter panel is mostly gone, I can see and clean the mounting surfaces for the new quarter panel.

The leading edge of the panel covers the B-pillar. A light coating of surface rust covers everything. 

Just a wire wheel and some time cleans it up nicely. Don't grind here, there are factory reference points called Master Control Surfaces that you'll want to preserve to line up new panels. (I found that secret detail in the factory weld and sealant manual).

 This is the top of the rocker panel where the quarter panel was mounted. Again, surface rust and body caulk, but nothing serious. I'm pretty sure the rocker panels are galvanized, so they should hold up pretty well.

More wire-wheeling and it's clean enough for the next step. Notice where I got a little over-zealous with the spot-weld cutter - it left little circles and thinned the metal there. When I replace the panel, I'll need to place my new plug welds to the side so I don't blow through the thin meal.

The trunk drop-off panel on this side is in bad shape. After stripping it with the wire-wheel, I found a lot of weak and very thin meal over the entire bottom four inches as well as the edges. The top is fine. When I got the car from Brett, there was a lot of oily dirt and debris in here that had clearly been sitting for a long time. I'm not surprised, just disappointed :(  This will need to be replaced.

Now it's time to test fit my new outer wheelhouse. The inner wheelhouse is still in place. On coupes of this year, the inner brace is welded to the top of the outer wheelhouse, making replacement fairly easy. On fastbacks, the inner brace is welded to the wheelhouse assembly lip. so replacing the outer wheelhouse is more trouble.

My clever/lazy solution was to drill all the spot welds on the brace all the way through. When I slide the new outer wheelhouse in there, it'll fit it between the lip on the inner wheelhouse and the brace so it'll be easy to plug weld in. Of course, this means I'll have to weld both sides since the holes go all the way through, but whatever. That's future-me's problem.

The new wheelhouse fits in nicely. I had to clean up the inner wheelhouse mating surfaces pretty well, but now the new part just slides in there and is held in place with the tension from the inner brace on top.

Rear view - here you can see the fit at the trunk drop-off.

Front view. 

More to come. Next up is more metal cutting and replacement!

Friday, March 17, 2017

Quarter Panel Repairs - patching the rusty inner wheel well

Here's a quick and dirty post on a patch job in the wheel well area. 

When the outer wheel well was cut out, I discovered a weak and rotten area of metal that is a common place to find rust. The inner and outer wheel well pieces are overlapped a little bit at the forward part of the assembly inside the well. The overlapped area tends to trap dirt and water being run around in there and eventually rust forms. I figured this was worth posting since it's probably happening on a lot of these cars by this point. The rest of the metal around here is in pretty good shape, so it could have been worse.

Once the outer wheel well was gone, the rot is exposed. This shot shows the intersection of the inner well, the floor pan, and the rocker panel. 

The bad metal is cut out easy enough.

Here's more rotten metal in the pile. It's about 3 inches by 4, and is completely eaten through very thin in several places, so I'm happy to have it out.

 The area is cleaned up in preparation for welding. Those two holes in the upper flange of the rocker panel aren't supposed to be there - that was a result of overenthusiastically drilling out a couple of spot welds that were holding the outer wheel well in place. I'll need to fill those holes before I put the new wheel well in.

 New patch made from 20 gauge metal. 

 The patch was butt-welded in and plug welded where the original spot-welds were before.

Welds cleaned up and it's good as new. It's much smoother than it looks, and I'm pretty happy with it. I'll trim the bottom and outer edge to the right shape later.  But you'll never see all this once the quarter panel work is done, as this will be covered with the new outer well and then covered with new sound deadener.  

Now I just have to patch a couple other holes here...