Muscletang needs new floor pans - advice?

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Qcode351mach

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Question Q: If nothing else, is it feasible to use the panel adhesive on the area where the pans meet the rockers, as opposed to the rest?

Just curious where the hazard factors in here.

-Kurt
No adhesive what so ever especially at the rocker as others have said it's a structural piece integral part of the unibody. The only place you could use would be a small patch to a existing good floor.

 
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Make sure you weld the pan in. DONT use adhesive, the floor is a major structural part of the car. If you don't mind seeing the seam, make it easy on yourself and overlap the seams. I butt welded mine and you cant even tell its there, but its time consuming and pretty challenging if you have never welded before. Buy a good spot weld cutter and some bits for it. Also get a cheap flanger/punch tool from harbor freight so you don't have to drill 100 holes by hand! http://www.harborfreight.com/air-punch-flange-tool-1110.html
Good tip about the butt weld bits. Didn't know them. I found this Blair set in Amazon: http://www.amazon.com/gp/product/B002XML5HK/ref=ox_sc_act_title_1?ie=UTF8&psc=1&smid=A1UMBRA5ZTBCX8 Are those good?

I don't have a big enough air compressor to run air tools. Forgive my lack of knowledge, what are the holes you talk about for? I am planing on going the lap joint weld route.

 

73MustangCoupe

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I have an Eastwood 135 and it has done very well for me. If you have 220V, then the 175 would be even better. But for sheet metal, the 110V welder works very well. And definitely use gas. Flux core totally sucks, and is even worse with sheet metal. As far as the spotweld cutter, the Blair 11096 has a 1/8" pilot bit, so will leave a small hole. The Blair 11082 would be a better bet. Check out http://www.autobodynow.com/collections/blair/products/blair-equipment-spotweld-cutter-kits-11082.

Good luck.

 

cudak888

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Now I have a question about the passenger side rocker. Is that top piece missing a problem? should something be welded there or it doesn't matter?
Really strange that it should be chopped up like that (makes me think of The French Connection!), as the rocker itself doesn't appear damaged anywhere except the inside, and a hit on the outside that would have done the same to the inside would have been nasty enough that the rocker wouldn't look like that today - nor the car.

Perhaps this was a parts car at one time, and that panel was cut out of it as a donor?

Here is the same area on a '73 rocker:

30xj5f9.jpg


No adhesive what so ever especially at the rocker as others have said it's a structural piece integral part of the unibody. The only place you could use would be a small patch to a existing good floor.
Makes sense - though why is 8115 touted to have a stronger tensile strength than steel?

Would it be unacceptable if someone looking for a beer-budget workaround were to plug weld most of the panel, but use a combination of plug welds and 8115 on a lap joint at the trans tunnel?

I'm not necessarily advocating lapping the panels, but for someone who wishes to do so, it would seem as if using the 8115 and plug welds would be a long-lasting method to seal the lap joint (provided it's epoxy to epoxy). Unless 8115 is particularly flammable...

-Kurt

 
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Really strange that it should be chopped up like that (makes me think of The French Connection!), as the rocker itself doesn't appear damaged anywhere except the inside, and a hit on the outside that would have done the same to the inside would have been nasty enough that the rocker wouldn't look like that today - nor the car.

Perhaps this was a parts car at one time, and that panel was cut out of it as a donor?
Good points. Then it doesn't make sense. Could it be that they cut it to check for damage or rust? But if so, why cut it so much.

I thought of an accident because that door doesn't close as easy, but that could also be some misalignment of the hinges or lock.



Makes sense - though why is 8115 touted to have a stronger tensile strength than steel?
The epoxy has a high tensile strength, but the assembly will be weakest at the epoxy-panel interphase, which will make the whole joint weaker. Maybe that's the issue.

Would it be unacceptable if someone looking for a beer-budget workaround were to plug weld most of the panel, but use a combination of plug welds and 8115 on a lap joint at the trans tunnel?

I'm not necessarily advocating lapping the panels, but for someone who wishes to do so, it would seem as if using the 8115 and plug welds would be a long-lasting method to seal the lap joint (provided it's epoxy to epoxy). Unless 8115 is particularly flammable...
If I were to lap weld all around, what should I use to seal the lap joint? Some kind of silicone or similar?



As far as the spotweld cutter, the Blair 11096 has a 1/8" pilot bit, so will leave a small hole. The Blair 11082 would be a better bet. Check out http://www.autobodynow.com/collections/blair/products/blair-equipment-spotweld-cutter-kits-11082.

Good luck.
Thanks found the Blair 11082 in Amazon.


A friend has a Hobart 140 welder. He hardly use it, so he will let me borrow it for a few weeks. I will practice and do the job with his then I can save some money to get one for myself. I spent too much purchasing parts this weekend.

 
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cudak888

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Good points. Then it doesn't make sense. Could it be that they cut it to check for damage or rust? But if so, why cut it so much.

I thought of an accident because that door doesn't close as easy, but that could also be some misalignment of the hinges or lock.
How are your door gaps?

As far as the spotweld cutter, the Blair 11096 has a 1/8" pilot bit, so will leave a small hole. The Blair 11082 would be a better bet. Check out http://www.autobodynow.com/collections/blair/products/blair-equipment-spotweld-cutter-kits-11082.

Good luck.
Thanks found the Blair 11082 in Amazon.


A friend has a Hobart 140 welder. He hardly use it, so he will let me borrow it for a few weeks. I will practice and do the job with his then I can save some money to get one for myself. I spent too much purchasing parts this weekend.
+1 for both the Blair 11082 and Hobart 140 MIG welder. I used the same cutters on the spotwelds of my car - AND the same welder to put it back together. You'll love the Hobart; it's nicer than the comparable Lincoln 110's.

-Kurt

 
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Good points. Then it doesn't make sense. Could it be that they cut it to check for damage or rust? But if so, why cut it so much.

I thought of an accident because that door doesn't close as easy, but that could also be some misalignment of the hinges or lock.
How are your door gaps?
Here is a picture.

IMG_9696-crop.jpg

 

cudak888

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Hard to tell with the bump strip on the back of the door. Same on my '71. Wouldn't dare remove them - they'll take your paint with 'em.

-Kurt

 

turtle5353

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Make sure you weld the pan in. DONT use adhesive, the floor is a major structural part of the car. If you don't mind seeing the seam, make it easy on yourself and overlap the seams. I butt welded mine and you cant even tell its there, but its time consuming and pretty challenging if you have never welded before. Buy a good spot weld cutter and some bits for it. Also get a cheap flanger/punch tool from harbor freight so you don't have to drill 100 holes by hand! http://www.harborfreight.com/air-punch-flange-tool-1110.html
Good tip about the butt weld bits. Didn't know them. I found this Blair set in Amazon: http://www.amazon.com/gp/product/B002XML5HK/ref=ox_sc_act_title_1?ie=UTF8&psc=1&smid=A1UMBRA5ZTBCX8 Are those good?

I don't have a big enough air compressor to run air tools. Forgive my lack of knowledge, what are the holes you talk about for? I am planing on going the lap joint weld route.
Blair makes a good spot weld cutter but make sure you don't use the one with the center drill bit. you want the one with a pin in the center. Make sure you center punch the spot welds really good before drilling so the bit doesn't walk all over the place and break.

When you weld your pan in at the lap joint I would just punch holes around the edge every 1 1/2 inches and do rosette welds. You can weld the entire perimeter, but I don't think its necessary. A bunch of nice tight spot welds will do the trick. You don't need much of an air compressor to use that tool I linked you to. It sure beats drilling a bunch of holes. You can use some self tapping screws to pull the panels tight together for the welds. Then after welding take out the screws and weld up the holes. After your done you can use some 3m seam sealer in a caulking gun to seal the lap joints both top and bottom of the car. Here is an example of the welds. NOT a mustang but will give you an idea, a 59 Studebacker I put floor pans in. Last pic is just one I found online.

pan.JPG

pan2.JPG

pan3.JPG

pan4.JPG

floor1.jpg

 
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Blair makes a good spot weld cutter but make sure you don't use the one with the center drill bit. you want the one with a pin in the center. Make sure you center punch the spot welds really good before drilling so the bit doesn't walk all over the place and break.

When you weld your pan in at the lap joint I would just punch holes around the edge every 1 1/2 inches and do rosette welds. You can weld the entire perimeter, but I don't think its necessary. A bunch of nice tight spot welds will do the trick. You don't need much of an air compressor to use that tool I linked you to. It sure beats drilling a bunch of holes. You can use some self tapping screws to pull the panels tight together for the welds. Then after welding take out the screws and weld up the holes. After your done you can use some 3m seam sealer in a caulking gun to seal the lap joints both top and bottom of the car. Here is an example of the welds. NOT a mustang but will give you an idea, a 59 Studebacker I put floor pans in. Last pic is just one I found online.
Thanks. These are very helpful tips. This is a very doable project. I can't wait to get going. I ordered the Blair cutter you recommended, #11082 w/o pilot bit. The panels are backordered at CJ Pony, but I still have ways to go before I start welding them together. I first have to remove some of the fiberglass to locate the factory spot welds, cut them, remove the seat risers, cut the old panels out, cut the new panels in, drill and then lap weld. After that I guess seal, paint, and enjoy!

BTW, what 3M seam sealer do you recommend? I searched and there are many options.


This forum is amazing. Your help is greatly appreciated and thanks for giving me the confidence to tackle this job and the many others I have asked questions about.

 
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The saga continues tonight. I peeled away more and more of the fiberglass to find the floors in very bad shape. I am kind of afraid of peeling more to find bad news. I am sure a lot of you have gone through this. I don't yet know how far up into the firewall and into the transmission tunnel the replacement floor pans go. I also found out that the driver's seat riser is a goner and found some rust starting though under the rear seat panel (name??).

Questions:

-Where is a good source for the sear riser pan? I found one at $75. Also, is the pan under the rear seat fabricated? the rust under the rear seat appears minor, but still have to investigate more.

-The passenger seat riser does not look like the driver's side. The passenger was probably replaced when the car was restored 12 years ago. The riser has some areas of spot welds and some areas where they welded the edges (see picture). I assume that I take out the edge welds with the grinder.

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20141129_235427cropped.jpg

 
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cudak888

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Honestly, I'm only seeing surface rust in the rear seat area - perhaps it's the photo. The rot spots around the pedal area should be covered by the new pans. The riser will come out anyway for the installation, so you shouldn't have a problem.

That appears to be an original Ford replacement seat riser on the passenger's side, not the current repop (which only comes in the taller Coupe size, and is a nasty-looking piece of workmanship). You're lucky that this side is OK. I'd recommend sourcing a good original for the driver's side. It'll save you some installation headaches.

-Kurt

 
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turtle5353

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Your floor pans aren't crazy bad! The new pans will go up the trans tunnel 4-5 inches, so you will definitely cover your bad spots. The rear seat area doesn't look too bad. Wire wheel it and clean it up, then rust bullet the crap out of it. Should be fine. If your passenger seat pan is good try to save it. And CUDA is right about the repops only being for coupe and convertible, but you can easily trim them down to fit properly. If you can find a good used seat riser that would be easiest, but they are usually rotted on the bottom edge. I put the repops in my mach1 and they needed trimmed down to fit and while I was at, I moved them back about 2 inches for a little more leg room.

As far as what seam sealer to use, I just go to the local autobody supply shop and tell them I need body seam sealer in a caulking gun tube. They usually give me a 3m brand ,but I cant remember what it is off hand....sorry. Its not cheap...almost $20 a tube! But its good sticky stuff!!

If you have any more questions let us know! And don't forget the progress pics!!!

 
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cudak888

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If you can find a good used seat riser that would be easiest, but they are usually rotted on the bottom edge. I put the repops in my mach1 and they needed trimmed own to fit and while I was at, I moved them back about 2 inches for a little more leg room.
I have a pair of used pans with the risers on them - the driver's side is not great, but it may be better than what he has now.

I'll pull it out and take a photo for Tony this weekend. So long as I don't need it for the yellow car, I don't mind parting with it.

-Kurt

 
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I have a pair of used pans with the risers on them - the driver's side is not great, but it may be better than what he has now.

I'll pull it out and take a photo for Tony this weekend. So long as I don't need it for the yellow car, I don't mind parting with it.

-Kurt
Thank you Kurt, let me know.

1971 M-code Mach 1



The rear seat area has couple small areas where is rusted through. On the drivers side there is another fiberglass patch which i am afraid to remove. The picture is not the best.

That said, do i need to cut and weld some sheet metal to it, or is there another way to go.

1971 M-code Mach 1

 
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turtle5353

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I have a pair of used pans with the risers on them - the driver's side is not great, but it may be better than what he has now.

I'll pull it out and take a photo for Tony this weekend. So long as I don't need it for the yellow car, I don't mind parting with it.

-Kurt
Thank you Kurt, let me know.

1971 M-code Mach 1



The rear seat area has couple small areas where is rusted through. On the drivers side there is another fiberglass patch which i am afraid to remove. The picture is not the best.

That said, do i need to cut and weld some sheet metal to it, or is there another way to go.

1971 M-code Mach 1
You will need to cut out any holes and weld in some patches.....couldn't tell from the pics sorry. If its where the lower seat cushion sits, I don't believe they make patch panels for that area??? I may be mistaken but im sure someone on here knows for sure!! If not get some 16 gauge steel and cut a few patches for that area. the smaller patches are a little easier to practice your butt welding skills if you would like or you can just overlap it....up to you.

 

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The rear seat area has couple small areas where is rusted through. On the drivers side there is another fiberglass patch which i am afraid to remove. The picture is not the best.That said, do i need to cut and weld some sheet metal to it, or is there another way to go.
Rip up the fiberglass. Do it once, and do it right.

It's just steel replacement, and it's not even on the outside of the car. You're lucky!

-Kurt

 
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Thank you for the encouragement guys. Tonight after seeing the Badgers lose to Duke I released my frustration working on the car. I ended up removing most of the fiberglass in the area under the rear seat. Here are the pictures. There are areas with surface rust, some areas where pitting already started and some other areas where there are holes through.

Here is what I am thinking, but I need advice on how to properly proceed.

-The areas with surface rust are easy: clean/grind rust.

-The areas with surface pitting: this is a bit of an unknown. I guess I will start with cleaning/grinding the rust. Then check thickness. If too thin may have to replace area. However, how thin is "too" thin?

-The ares with through holes: replace local sheet metal plus clean and grind. I am thinking to cut holes around the area with a hole saw. Then I can use the same hole saw in new sheet metal and weld. Or cut sheet metal larger and lap join with adhesive. It may be trickier in the areas where folds exist. I will have to try replicating these folds as close as possible.

Two other questions about the second to last and last pictures.

-The second to last is the area where the fender meets the underseat panel. I started cleaning and started removing some black sealant. I assume this is the factory sealant so I stopped. The good news is that the area underneath is shiny sheet metal. Now, once I prime and seal that area how do I ensure that the union between the old sealant and new is proper?

-The last picture is the passenger's side where the underseat panel meets the floor panel and other sheetmetal. Hard to describe but hopefully the picture shows it. My question here, does this look factory? There is a gap between the panels in the lower right area of the picture that shows a larger than expected gap (circled area). You can actually see the garage floor through this gap.

20141203_234443_resized.jpg

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20141204_001636_resized.jpg

 
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Thank you for the encouragement guys. Tonight after seeing the Badgers lose to Duke I released my frustration working on the car. I ended up removing most of the fiberglass in the area under the rear seat. Here are the pictures. There are areas with surface rust, some areas where pitting already started and some other areas where there are holes through.

Here is what I am thinking, but I need advice on how to properly proceed.

-The areas with surface rust are easy: clean/grind rust.

-The areas with surface pitting: this is a bit of an unknown. I guess I will start with cleaning/grinding the rust. Then check thickness. If too thin may have to replace area. However, how thin is "too" thin?

-The ares with through holes: replace local sheet metal plus clean and grind. I am thinking to cut holes around the area with a hole saw. Then I can use the same hole saw in new sheet metal and weld. Or cut sheet metal larger and lap join with adhesive. It may be trickier in the areas where folds exist. I will have to try replicating these folds as close as possible.

Two other questions about the second to last and last pictures.

-The second to last is the area where the fender meets the underseat panel. I started cleaning and started removing some black sealant. I assume this is the factory sealant so I stopped. The good news is that the area underneath is shiny sheet metal. Now, once I prime and seal that area how do I ensure that the union between the old sealant and new is proper?

-The last picture is the passenger's side where the underseat panel meets the floor panel and other sheetmetal. Hard to describe but hopefully the picture shows it. My question here, does this look factory? There is a gap between the panels in the lower right area of the picture that shows a larger than expected gap (circled area). You can actually see the garage floor through this gap.
Looks like someone in the past used rust bullet type stuff or undercoating type stuff on the pans...hard to tell from the pics. That will hide a lot! Grind, wire wheel it off and clean that area up. I usually cut the small holes out with a body saw or cutoff wheel and make them square. A hole saw might distort your new patch. ??? Since you will be welding in the floor pans you might as well weld in all the patches. My personal preference is to weld anything I can. One way to tell if the metal is too thin....use a screw driver and try to poke through it. If you poke through it....too thin if not then your good. Use good common sense and judgment. Those small holes I would cut a nice square hole out and butt weld it in place for a seamless look, but if your not comfortable with that, then by all means do a lap joint weld. With the sealer new meeting old..... just make sure if you use the stuff from a caulking gun don't just make a nice bead and leave it there. You always want to run your finger down it to make sure it seals well and gets smoothed out nice. Just like caulking windows or a shower in your house. The last pic is really hard to see. but if its a seam in the panels coming open then you will want to clean it up and try to pull it together with a c-clamp or self tapping screw if possible, then weld it shut and grind it to look nice. good luck!!!

 
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The last pic is really hard to see. but if its a seam in the panels coming open then you will want to clean it up and try to pull it together with a c-clamp or self tapping screw if possible, then weld it shut and grind it to look nice. good luck!!!
Thanks for your responses. Here is a close-up but still not easy to see. It does not seem like coming apart. It just looks like the two panels were welded a bit a part. Teh gap is fairly consistent. It looks original or nicely redone. I just don't know if this is normal. I can try to add sealant and then close the gap with a clamp. If it is original welding it shut may not be the proper way.

Actually, some water comes through this hole while driving because the inside plastic panel had some water splash marks. Speculating, that could explain the rust. If water came up through there during driving the area may have stayed wet causing rust over time. It is weird that the car appears in such a good shape everywhere except these floor pans.

20141204_001636_resized-cropped.jpg

 
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