Author Topic: Best full floor Pan for 1970 challenger convertible  (Read 1753 times)

Offline wiging19

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Best full floor Pan for 1970 challenger convertible
« on: November 12, 2018 - 12:28:28 pm »
Been a while since I worked on this car.  Gave it to a guy to get running and he had it several years.  Just needed a tranny and engine.  Short story last year he died.  Have car back and one of the things holding us back is we needed to replace the floor pan since there the seam between floor panels was open across the floor bottom.  Just want to replace the whole floor pan (already did trunk and quarters ten years ago).  I just want the pan with all the features it had out of the factory.  I will have it professionally done once I have the part since it will have an original replacement hemi block from the 70's. 

I will also like recommendations on floor braces to have put in that provide good clearance under the car, improves the structure integrity of the frame considering the engine will have in the ball park of 650 hp and the body currently is straight.

Should I replace the tork boxes on the car when I have this other work done.  They look good except one in the past looks like it supported the car weight when it was lifted at some time in the past.  You know how the service people were in the 70's and 80's.  Thanks.




Offline Beekeeper

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Re: Best full floor Pan for 1970 challenger convertible
« Reply #1 on: November 12, 2018 - 01:13:46 pm »
I did a lot of what youre describing in one of my Challengers. My advice would be to go with any floor. AMD might be nicer but I used a different brand and it was very nice and half the price. I have used all sorts of brands for all kinds of metal components and I am not convinced AMD is worth the cost. You may need to cut out the seat belt reinforcement plates from the old floor and add them to the new floor. Not hard to do. While the floor is out, check the little side braces for integrity.

To add real structural stability for that kind of power, Id add sub frame connectors. I used the ones by US Car Tools and they are nice and look like the original frame rails as well. The same company makes torque boxes for all four points which I recommend. They also make braces that go under the front fenders and tighten up the handling if that interests you. I think the whole kit is only like $650 or so if I remember right.

Offline 70chall440

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Re: Best full floor Pan for 1970 challenger convertible
« Reply #2 on: November 12, 2018 - 02:36:03 pm »
I agree with Beekeeper on the second part of his post, not really on the first part. Between my Challenger and Cuda I have used a wide variety of sheet metal from a variety of vendors. I will say without reservation that AMD is superior to the others by a significant margin. It comes down to 2 main issues, fit and metal quality. I have found that while most of the panels will fit to one degree or the other AMD's overall quality (metal thickness, correctness in the stamping, and dimensions) are typically far better.

All this said, I might use someone other than AMD for something that won't be visible or isn't overly structural, but when possible I would definitely use AMD for things such as fenders and quarter panels. The floor is a judgement call because while it is structural (obviously) it is supported 360 degrees as well as via cross members. If you plan to use some sound deadener such as Hushmat it might be a wash as the deadener will add to the rigidity. 
Current Mopar
70 Challenger RT 440-6, 73 Cuda (under const)
05 Durango, 99 Dakota, 01 Ram 4x4, 14 2500 4X4, 10 PCP Challenger RT, 01 Viper GTS ACR, 52 B3B w/330 Desoto Hemi, 70 Hemi RR, 61 Jeep FC170
Past Mopars
9 x Challengers. AAR Cuda, 4 RR, 2 GTX, 4 Chargers, etc... (too many to list)

Offline Beekeeper

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Re: Best full floor Pan for 1970 challenger convertible
« Reply #3 on: November 12, 2018 - 04:09:08 pm »
I agree with Beekeeper on the second part of his post, not really on the first part. Between my Challenger and Cuda I have used a wide variety of sheet metal from a variety of vendors. I will say without reservation that AMD is superior to the others by a significant margin. It comes down to 2 main issues, fit and metal quality. I have found that while most of the panels will fit to one degree or the other AMD's overall quality (metal thickness, correctness in the stamping, and dimensions) are typically far better.

All this said, I might use someone other than AMD for something that won't be visible or isn't overly structural, but when possible I would definitely use AMD for things such as fenders and quarter panels. The floor is a judgement call because while it is structural (obviously) it is supported 360 degrees as well as via cross members. If you plan to use some sound deadener such as Hushmat it might be a wash as the deadener will add to the rigidity.

Yeah I cant argue this point. Anything cosmetic like a hood or fender is worth the extra money if it saves bodywork later. I was referring only to metal that is hidden like a floor. Ive done so many metal repairs on these Mopars that I have found they all require fitting. I just did an upper cowl on my other Challenger and I decided to spend the extra dough for an AMD. It fit like crap and it took me over an hour to get it massaged well enough to work. This is the third upper cowl replacement I have done. The first two were goodmark brand and fit like a glove. This one was AMD and fit horrible.


Offline wiging19

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Re: Best full floor Pan for 1970 challenger convertible
« Reply #4 on: November 12, 2018 - 04:34:51 pm »
Thank you both for your feedback.  I know the quality of the products have varied over the years and I wanted a current perspective on the best path.  I'm comfortable going with the AMD product if it fits better, is closer to original spec's and definitely looking for heavier metal in the product.  Do you think I would be possible to ask AMD if it would be possible to have a sheet stamped with heavier metal than normal?

I will definitely add the Hushmat based on the information you provided on increasing the rigidity.

The sub frame connectors are an area I know is a must.  I'm just concerned with the extra work US tool kit requires to fit properly.  I wonder if I'm putting in a full floor is that something that can be put on the floor pan before the floor pan is put in the car?  That would be easier to do than put it on after the floor is in.  On the other hand that may not be practical which is why I ask.  A case of not knowing what is needed related to this kind of body work.  Thanks.

Offline Beekeeper

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Re: Best full floor Pan for 1970 challenger convertible
« Reply #5 on: November 12, 2018 - 04:51:39 pm »
Thank you both for your feedback.  I know the quality of the products have varied over the years and I wanted a current perspective on the best path.  I'm comfortable going with the AMD product if it fits better, is closer to original spec's and definitely looking for heavier metal in the product.  Do you think I would be possible to ask AMD if it would be possible to have a sheet stamped with heavier metal than normal?

I will definitely add the Hushmat based on the information you provided on increasing the rigidity.

The sub frame connectors are an area I know is a must.  I'm just concerned with the extra work US tool kit requires to fit properly.  I wonder if I'm putting in a full floor is that something that can be put on the floor pan before the floor pan is put in the car?  That would be easier to do than put it on after the floor is in.  On the other hand that may not be practical which is why I ask.  A case of not knowing what is needed related to this kind of body work.  Thanks.

I doubt they would make a special stamping but even if they did, the entire car is a bunch of similarly thin pieces of metal all spot welded together. Seems to me that the floor could only give you so much when the rockers and other structural stuff like the roof are still pretty thin.

One thing I want to do on mine which I Hope may add some strength is to go around the whole car in and out and weld up the overlapping metal here and there. The entire car is simply one piece of thin overlapping metal after another held only by spot welds, many of which weaken and break over time. I was thinking that a bit of time with a welder could help stiffen stuff up. I welded up my k frame and lower control arms like this just to get things a little stronger.

I agree that you could probably do some fitting of the US Cartools rails along the floor before installing but Id get the floor trimmed up perfect first, then fit the rails outside the car. Id wait to weld the rails on though after the floor is finally installed. According to directions, they recommend the car be loaded down before welding in the rails so it sits down properly.


Offline larry4406

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Re: Best full floor Pan for 1970 challenger convertible
« Reply #6 on: November 12, 2018 - 06:23:23 pm »
I think the US Cartools frame connectors get a bad rap regarding fit. I did mine while on a rotisserie. Put in place, scribe, grind, check again, etc. Several hours with tunes and a few beers and was done in a day. There are holes in the floor plan which I installed bolts and wood blocking across the connectors to pull all tight to floor for welding.

Offline Beekeeper

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Re: Best full floor Pan for 1970 challenger convertible
« Reply #7 on: November 12, 2018 - 07:07:07 pm »
Dont use a typical tabletop grinding wheel or even a portable grinder. Use a handheld power tool like a 120v sander with a 4 disc in 24 grit. It will make very short work of removing metal. Youll probably go through a few discs but they are cheap. I use the $10 harbor freight unit with a $4 backer plate. I like the cheap ones for this kind of work so I can abuse it to death and toss it later. Good for at least 100 hours of heavy abuse. You should have them fitted to the floor in less than an hour.

I definitely like your idea of getting them fitted out of the car.

Offline 70chall440

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Re: Best full floor Pan for 1970 challenger convertible
« Reply #8 on: November 12, 2018 - 09:32:32 pm »
I used the US car tools SFCs as they fit the floor contours, however I made my own torque boxes, apron braces and lower radiator brace, also welded up the K frame. It was efficient and not overly difficult but purchasing the items would have been faster.
Current Mopar
70 Challenger RT 440-6, 73 Cuda (under const)
05 Durango, 99 Dakota, 01 Ram 4x4, 14 2500 4X4, 10 PCP Challenger RT, 01 Viper GTS ACR, 52 B3B w/330 Desoto Hemi, 70 Hemi RR, 61 Jeep FC170
Past Mopars
9 x Challengers. AAR Cuda, 4 RR, 2 GTX, 4 Chargers, etc... (too many to list)

Offline 340challconvert

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Re: Best full floor Pan for 1970 challenger convertible
« Reply #9 on: April 09, 2019 - 10:13:45 am »
Just my own experience;
I purchased quarter panel lower patch panels to be cut into patches for my lower quarters
I bought AMD and Goodmark panels to compare.  Both fit the areas reasonably well, but the GM panels left out some details on the bottom edge.  They could be used but lacked the "details" of the AMD panel.
Pics of the two units
1970 A66 340 Y-1 convertible