Tail Panel removal - need procedure

72mokk1 said:

There is no lead in that panel. You need to drill out the spot welds. You can buy a spot weld cutter or use and over sized drill to remove them.

Click to expand...

Stanglover said:

You need a spot weld drill. It's like a mini hole saw with a spring loaded pointed tip. Center punch (spring loaded type) the center of the weld to guide the drill point. Only go through as far as the tail panel metal. It will leave a little 'tit" that can be ground off.
I've not actually done this on a panel, but done similar in my past work. If I remember, my body guy drilled appropriate holes in the tail panel so as to weld through, so they look like spot welds.

Click to expand...

GERMYS_72 said:

View attachment 93786 this is what I ordered, I think it's spring loaded but not sure

Click to expand...

Stanglover said:

That's it. That one is double ended which is a bonus.

Click to expand...

GERMYS_72 said:

I also saw a video where you lightly tap a plasma cutter on the spot weld and it melts it away quick.

Click to expand...

Bentworker said:

When did mine I used a 3/8” / 10mm belt sander with a 36 grit belt. Nice thing about that method is you don’t end up with holes in your good metal from the pilot of the spot weld drill. You just grind away at the spot weld on the tail panel side of whatever it is sandwiched with. As you are throwing away the old tail panel it does not matter that you are making little square holes in it with the belt sander. For videos of this technique look on YouTube. About 2 minutes in on this vid. Make sure that on the quarter panels you remove the spot welds from the inside of the trunk. Don’t grind away at your quarter panels.

Also,
The repop tail panels are very likely to have two problems.

1) The tail light mounting bracket location is sketchy at best. Test fit tail lights before you install the panel. You will likely need to move at least one of the brackets.

2) When the holes for the tail lights are stamped it does not seem like the sheetmetal around the tail light hole is trimmed to an even measurement. In some places it may be 5mm, others 15. Again, check fitment of tail lights. Mark and trim metal to make the lip even. Otherwise you will have issues making your tail lights fit correctly and be weathertight.

Click to expand...

GERMYS_72 said:

I also saw a video where you lightly tap a plasma cutter on the spot weld and it melts it away quick.

Click to expand...

Bentworker said:

When did mine I used a 3/8” / 10mm belt sander with a 36 grit belt. Nice thing about that method is you don’t end up with holes in your good metal from the pilot of the spot weld drill. You just grind away at the spot weld on the tail panel side of whatever it is sandwiched with. As you are throwing away the old tail panel it does not matter that you are making little square holes in it with the belt sander. For videos of this technique look on YouTube. About 2 minutes in on this vid. Make sure that on the quarter panels you remove the spot welds from the inside of the trunk. Don’t grind away at your quarter panels.

Also,
The repop tail panels are very likely to have two problems.

1) The tail light mounting bracket location is sketchy at best. Test fit tail lights before you install the panel. You will likely need to move at least one of the brackets.

2) When the holes for the tail lights are stamped it does not seem like the sheetmetal around the tail light hole is trimmed to an even measurement. In some places it may be 5mm, others 15. Again, check fitment of tail lights. Mark and trim metal to make the lip even. Otherwise you will have issues making your tail lights fit correctly and be weathertight.

Click to expand...

turtle5353 said:

View attachment 93788View attachment 93789View attachment 93790View attachment 93791View attachment 93792View attachment 93793View attachment 93794View attachment 93795View attachment 93796You will need more than 1. I buy them by packs of 5. If the edge catches it will break off a tooth. After a few teeth break you need to flip the tip and use other side. I keep a handful in my welding cart at all times.
The spot welds can be hard to locate sometimes but with patience you will find them. It’s a pretty straightforward job. Just don’t forget to remove the trunk latch bracket too. Take a few measurements so you put it back in same place and trunk lid closes properly. There’s also a stiffening bracket by each tailight. When you go you reassemble the tailight panel, I would recommend attaching it with self tapping screws before welding. Then install the rear quarter extensions, rear valance, and rear bumper. Make sure everything lines up nicely before welding. If you need to make adjustments it’s easy with self tapping screws. Once you’re happy with the fit, tear it all back off and start welding. Any more questions let me know.

Click to expand...

Hemikiller said:

Locating the welds can be a challenge. I used a junk putty knife to force the panels apart slightly, which will distort the metal at the spot welds.

Which cutter you use depends on the location you're working on. The left and right sides, you can use a spot weld cutter, a drill, or any method that preserves the outer sheetmetal. Along the trunk floor, you want to make sure you use something that'll leave the trunk floor/rear crossmember intact and not put holes in it. The spring loaded spot weld cutter will leave a disc of metal that needs to be removed, the other cutter you ordered will remove the metal as it cuts, but be sure to not go into the underlying panels too much.

Another great way to do this is to use an air file with a 1/2" belt. Makes short work of the spot welds. They're heavily used in professional auto body shops, and they're great for dressing down your rosette welds when you're done.

https://www.amazon.com/gp/product/B00L50MKJS

If you have a later D3ZZ NOS panel, it likely has the holes for the '73-only bumper filler panel, which need to be filled for a 71/72 car.

Lastly, and I can't stress this enough, fit, fit and refit *everything* before you commit to welding for keeps. Taillight panel, rear valance, taillights, trunk lid and end caps. Fit it all together to ensure you won't discover an issue after it's welded solid.

Click to expand...

Hemikiller said:

Locating the welds can be a challenge. I used a junk putty knife to force the panels apart slightly, which will distort the metal at the spot welds.

Which cutter you use depends on the location you're working on. The left and right sides, you can use a spot weld cutter, a drill, or any method that preserves the outer sheetmetal. Along the trunk floor, you want to make sure you use something that'll leave the trunk floor/rear crossmember intact and not put holes in it. The spring loaded spot weld cutter will leave a disc of metal that needs to be removed, the other cutter you ordered will remove the metal as it cuts, but be sure to not go into the underlying panels too much.

Another great way to do this is to use an air file with a 1/2" belt. Makes short work of the spot welds. They're heavily used in professional auto body shops, and they're great for dressing down your rosette welds when you're done.

https://www.amazon.com/gp/product/B00L50MKJS

If you have a later D3ZZ NOS panel, it likely has the holes for the '73-only bumper filler panel, which need to be filled for a 71/72 car.

Lastly, and I can't stress this enough, fit, fit and refit *everything* before you commit to welding for keeps. Taillight panel, rear valance, taillights, trunk lid and end caps. Fit it all together to ensure you won't discover an issue after it's welded solid.

Click to expand...

mrgmhale said:

I do believe your tail section might actually look worse than ours looked on our 71 Mach 1. I am pretty good with mechanical and electrical diagnostic and repair work on these First Generation Mustangs. But I have never had neither the artistic flair or patience with body and pait work. That takes a much different skill set whan what I have. Fortunately I learned that long ago.

Anyway, FWIW I purchased a tail panel to replace ours due to rust around the taillight pod areas. I actually thought that it might be a fun project, with me being recently retired, to learn how to do body work. Well, once the new panel arrived and I looked at what was going to be involved, I scampered off to a vehicle restoration facility in our area to have them do all the heavy lifting.

Well, what I thought would be a quick tail panel job began to look more formidable than I had previously thought. It turned out there was a lot more rust, under the trunk lid weatherstripping, very much looking like what you have going on with your trunk weatherstrip seating area. With some more digging it was found a lot of deep seated rust had taken hold under the metal trim around the rear windows and windshield. What had begun as a $2,000 - $4,000 side project ended up becoming a project costing far more than the car will ever be worth - ever, ever ever. But for love of the breed, and due to a commitment I made to the person I purchased the car from, we bit the bullet with both eyes wide open.

The final result is spectacular. Amazingly, the underside was in really great condition, as well as all engine bay, and the uni-body spots other than the lower quarter panels. We had the panels needing to be repaired resectioned with new panels, retaining as much original metal as we could. And rather than using plastic filler we opted to have the low spots and seams corrected with lead. Very costly, bur the result speaks for itself.

I think that had I not been so enamored with that particular Mustang, and had not made a commitment to the seller, I would have likely sold the Mustang to someone looking for a fun and great running crash derby vehicle. It would have been less costly for us to have cut our losses and look for another 71-73 Mach 1 (or even Boss 351) that had no rust issues.

So why all of this writing? Just a suggestion to look under the rear window and widnshield glass trim to see if there is any deep seated rust, as well as looking at other panels and undercarriage parts needing to be replaced or repaired. BEtter to find it now before you take an even somewhat deep dive into the tail panel only to find out you have some really serious rust issues hiding from you.

Also, our tail panel was a repop, not NOS. I have some water leakage with the taillight pods. I have purchased an ultrasonic sensor and generator to use to locate the leakage points so I can correct and/or seal the leaks. The ideaq is to turn on the ultrasonic generator, close the trunk, then use the sensor to find where the ultrasonic waves are coming from. This same technique can be used to help locate door glass air leaks that can cause unnerving wind sound when driving:

https://tracerproducts.com/tp-9367l-marksman-ii/


Some progress photos of our deep re$toration project, ugly warts and all:

https://youtu.be/y0MiVAFj_sQ


Our 73 Mach 1 on its last day of its deep re$toration, after 13 1/2 months:

https://youtu.be/_Fl0B-qmlLI

Click to expand...