Patching LH Rear Inner Wheelhouse

I had left off with the removal of the braces in the left rear of the car revealing some deterioration in the front lower portion of the inner wheel house so I felt the need to patch this area.

First, I had to mark off where I was going to make the cut such that I could bypass the existing patch and replace the whole area. I used blue masking tape for this because it allows me to see the cut line through the sparks of the angle grinder.


Removal of this section of the wheel house exposed some deteriorating metal in the floor to seat transition panel.

This is the deterioration of a part of the floor to seat transition panel where it met with the inner wheel house. This same damage was evident on the right side of the car as well where I had made a similar patch.


So, the first thing I had to do was to cut away the ragged, rusted metal in a shape that a patch can be easily made for.

I cut a patch of 20 gauge sheet metal to fit the missing area, welded it in, and ground the welds flush. Then I cut a curved strip of similar metal to approximate the original flange that had rusted away, welded it on, ground the welds, and coated the area with weldable primer.

Now that I had the weld areas clean, it came time to make the patch for the wheel house. To do this, I used a reproduction wheel house from NPD. I used the original metal that I had previously removed as a template to cut the new metal.


It's important here to not cut exactly on the line but leave at least 1/8" above the line to compensate for the metal removed by the angle grinder cutting wheel.


I could then fit the new patch to the original inner wheel house.




I then marked the position of the new flange on the patch with a white grease pen, laid out hole locations for the plug welds and drilled the plug weld holes.

Finally I was able to butt-weld the new patch into place and grind the welds flush. I had some trouble with my welder heat settings on this task. I couldn't seem to get the settings right and blew through in several places causing me to have to patch my patch... blah!

Finally, I plug welded the overlap tab from the outer wheel house over the inner wheel house. This is where the inner rocker will reside as it butts up against the wheel house from the other side.

Testing the Sand Blasting Cabinet

Earlier in the week I had purchased a 50 lb bag of "Green Diamond Fine Abrasive" media for the new blasting cabinet as the glass bead I have didn't do a very thorough job of removing rust but rather just polished up the rust a bit. I rigged my shop vac up to the vacuum port I discovered on the back of the box and gave the blasting another shot on the brace and rear torque box cover parts I had previously removed. You can see from the image below that it did a much better job than my first test and in a fraction of the time, however, I still didn't get complete removal since splotches are still evident. This is good enough to be treated with Ospho and ZeroRust but I'd like it better. Two things on the cabinet need improved; 1) It needs steeper sides to allow the media to drop down and be pickup up by the blaster hose and 2) It needs the dust collection to be better balanced as my shop vac overpowered the cabinet's filter's ability to replenish the air such that the gloves got very stiff from there being such a high vacuum within the cabinet.

Finishing Left Rear Removal

I left off with the left rear inner rocker needing to be removed with a few chunks of metal in the way before I could even cut out the last section. I had removed the rear torque box cover last time (rounded metal piece bottom center of picture), the door jamb brace (A shaped piece on the right), and the rear trunk to floor brace (flat, curved piece on the left).

After I had removed the torque box cover, I started by removing the spot welds of the door jamb brace and then used a cutting disc on my angle grinder to cut the seam welds on the top and bottom and finally, used an air chisel to pop the part off.

Next I cut the trunk to floor brace in half and then cut away the seam welds at the top and the floor spot welds at the bottom and on the inner rocker and chiseled the part out of the car.

After removing the brace, I cut away the floor back to the rear trunk transition panel.

Finally, I was able to cut across the top of the remaining inner rocker and gain access to the spot welds that were holding it to the top of the outer rocker flange. I then finished up by cutting away the rusted lower flange from the bottom of the outer rocker.

The picture below indicates what the finished job looks like before wire brushing the scale rust and treating and preparing the interior of the panels that are newly exposed in anticipation of the new parts to be welded in. I can see that I'll need to patch the lower section of the inner wheel house as I previously did on the right side.

Patching Left Front Floor Support Part 2

I got a lot done today. If you read the last blog entry, you'll see that I left off with fitting the rear frame patch along with the front floor support rail. Today I started off by tacking the frame rail patch in place and marking the location on the floor support where it contacts the frame rail with a grease pencil. Then I was free to cut away the old, rusty lower drivers seat reinforcement.


Next I removed the floor support rail and was free to weld the new patch onto the cut-away section of the lower rear edge of the frame rail on both sides.


With the lower seat reinforcement out of the way, I could now remove what was left of the inner rocker all the way to the rear of the car.

The rear of the car... well, that's another issue altogether. As you might recall from my previous blog entries on the passenger side of the car, this area is reinforced with a couple of well-welded in braces, a rear torque box, the inner rocker, and it all merges with the rear wheel well. Quite a bit of stuff to untangle and here it is in it's virgin state.


First I needed to see what I was working with so I had to remove all of the debris and ancient seam sealer.

The first metal to be removed is the floor area around the rear torque box followed by the rear torque box cover. The new Blair spot weld cutter made this part of the job go very fast compared to the other side. This is what was inside the rear torque box. A pile of rusted steel and various other debris. I should make a reality show on SciFi because Ghost Hunters has nothing on me. THIS is what scary really looks like.

Patching Left Front Floor Support Part 1

I've received some new sheet metal from NPD. A front floor frame patch, a front floor support rail, and a driver's side firewall extension. I cleaned them up with degreaser and acetone, coated them with Ospho, and then coated them with PPG DP74LF epoxy primer.

Also with the sheet metal parts, I received a heavy-duty Blair spot weld cutter. It works like the economy spot weld cutters but has a much more aggressive, and stronger, cutting blade and chews through the spot welds with a lot less effort.


This new cutter gave me the motivation to start tearing through the welds that attach the inner rocker to the outer rocker and I made some progress in just a few hours. I left the lower seat reinforcement in place so I could use it to fit the new rear floor support rail and the front floor support patch.



I needed to make the patch first because I had cut the old rusted floor support due to the fact that it looked like swiss cheese. So, I painstakenly, surgically removed the badly damaged bottom portion of the front floor support from the badly damaged front floor support rail and straightened it up to use as a template for cutting the new patch out of the new front floor frame patch metal I had just received from NPD.

I have recently purchased some disc brake assemblys scavanged from a 1971 Ford Ranchero and thus needed to get a sand blasting cabinet to clean them and the various other rusty parts from this Mustang. The above hunk of rusty metal was the initiation test for the new blasting cabinet. Using the medium sized nozzle for the included blasting gun, the load didn't seem to tax my smallish air compressor too much. I could blast for about 30 seconds continuously before the compressor would need to restart and then continue for quite a while longer while it ran. I think it'll work fine although it may work better with a so-called pressure pot blaster. I think for the above test, I should have used an aluminum oxide media rather than glass beads as the glass beads did take off some rust but really just shined up the part.

Aaaaanyhoo, after cutting out the new patch, I test fitted it and the rear floor support against the lower seat reinforcement pan and the tunnel cross member. You can see the new patch tucked into the floor support rail where it's supposed to reside. Next I need to tack it in place, remove the rear floor support and then weld everything back in. Only then can I cut away the old lower reinforcement and finish removing the old inner rocker.

Driver Side Torque Box & Floor Support Removal

Mission complete on the passenger side of the car so it's time to start on the drivers side. I began by re-leveling the car and repositioning the front jack stands. Having accomplished that, I moved onto the driver side torque box.

See? Doesn't look to be in that bad of a condition other than a hole in the bottom right? Well, the proof of the pudding is under the crust so to speak so I scraped away the undercoating and found a layer of... Bondo?


I wondered what was being hidden on a torque box of all things. A Dent? A torque box isn't exactly the kind of place I'd have expected aesthetic scrutiny. So, I chipped away at the edges until I found what was being hidden. A 20 gauge patch of sheet metal riveted to the front of the torque box and covered with filler. Well, the hole surely couldn't have been that bad right?

WRONG! Last time I checked, Bondo is not a structural material. It's for hiding things. Hiding things from people who pay you good money to "restore" their car. So A) The sheet metal was way too thin for the job, 20 gauge as opposed to 14 gauge. B) The sheet metal was riveted to the structural steel instead of welded or, hell, even brazed. C) The rust was not repaired and continued to destroy what was left of the torque box, frame rail, floor support, and inner rocker. D) The whole mess was covered up by a layer of Bondo and forgotten. The whole thing stinks of fraud to me and I feel sorry for the previous owner who likely paid some loser to screw him over.

I cut off the front of the torque box and discovered where all of the rust from the other structural members has been collecting for all of these years. "Hey honey, do you hear a rattling noise? Like a maraca?".

I spent another couple hours cutting and removing everything. The floor support and the bottom of the front frame rail were toast so I cut them out to the lower seat reinforcement along with the box portion of the inner rocker and a hunk of floor pan. You can see the bottom of the frame rail laying on the floor there with the old floor support cradling it... rustily. At this point I had been manhandling various cutting implements for a good solid 4 hours and my wimpy computer programmer arms were getting tired so I knocked off for the day and took a shower.

Finishing Up Right Rear

I spent the weekend doing a few random tasks toward the back of the car, including grinding down the various spot welds I'd made welding in the structural members on the right side of the car and cleaning up the rear torque box cover and hammering it back into shape.

I became sidetracked by a rust hole about a 1/4" diameter in the bottom of the rear door jamb. I didn't take a detailed image of the area but I was able to crop and enlarge this area from another photo to give you an idea of the damage:

I then repaired the area in an hour or so without taking photos of the process because it was mostly experimental just cutting out rust until it was gone and then making a couple of patches from 20 gauge sheet metal, butt welding them in and grinding. This is a really lousy picture of the repair upon completion but it looks okay in real life. You shouldn't be able to tell it was there after paint.

I ran some seam sealer in the various seams within the rear torque box:

I then plug welded the original rear torque box cover back into place. I made a mistake on the lower portion of the torque box where I welded the front of it to the bottom of the inner rocker. The problem was that there's a 2" section of the torque box cover that's supposed to fit between the bottom of the torque box and the inner rocker so I had to grind out a couple of welds to get this cover to fit back as designed. Got it done though and it fits nicely.

The last task for this weekend involved welding the back of the inner rocker to the bottom extension of the front wheel well and trimming it up.
Except for the front firewall toe pan, the right side of the car structural is complete. This marks a milestone in the restoration of Ol' Rusty.