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Discussion Starter #1
Hello everyone,
I'm considering adding a trunk separator panel to my 1970 Mustang coupe, both to increase torsional stiffness and to reduce the chance of fiery death in the event of a rear-end collision. I figure I'll just take a flat piece of metal and cut it into shape.
I've seen both aluminum held in with sheetmetal screws, and steel welded in. I imagine welded-in steel would do significantly more to increase torsional rigidity, but would be much harder to remove in the future. For anyone who's welded in a "trunk firewall," was rear shock nut access a problem afterwards? My interior is still out at the moment, so welding is not a problem.
Thanks!
 

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Hello everyone,
I'm considering adding a trunk separator panel to my 1970 Mustang coupe, both to increase torsional stiffness and to reduce the chance of fiery death in the event of a rear-end collision. I figure I'll just take a flat piece of metal and cut it into shape.
I've seen both aluminum held in with sheetmetal screws, and steel welded in. I imagine welded-in steel would do significantly more to increase torsional rigidity, but would be much harder to remove in the future. For anyone who's welded in a "trunk firewall," was rear shock nut access a problem afterwards? My interior is still out at the moment, so welding is not a problem.
Thanks!
Accessing the shocks would be darn near impossible unless you had a removable center panel to reach them.

I've never bothered to do this. Shark bite is more common than Mustang Flambé.
 

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You might want to think about a Tank Armor plate instead of going through all the hassle I envision you having making a separator plate to bolt/weld to the back of the rear seat frame (I'm assuming this is your intent). Much better than your plan (IMO) and a whole lot easier. It's what I'm doing for my car.

Search - Tank Armor
 

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You might want to think about a Tank Armor plate instead of going through all the hassle I envision you having making a separator plate to bolt/weld to the back of the rear seat frame (I'm assuming this is your intent). Much better than your plan (IMO) and a whole lot easier. It's what I'm doing for my car.

Search - Tank Armor

I put Tank Armor in my 66 Vert project. Reasonably impressed with the strength. Seems to add a lot of rigidity and blocks the tank from the trunk largely. I have a sheetmetal piece for the divider but i am thinking about not using it. Not only would I need access to the shocks but the convertible pump as well.
 

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I've never bothered to do this. Shark bite is more common than Mustang Flambé.
Very true. If the flaming Mustang gas tank explosion was a typical thing, then we wouldn't have Kelly hanging out with us after Jane took a 45 mph shot to the trunk area.
 

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The rivnut thing is genius... but honestly, I don't think a dynamite covered separator panel will reduce noise very much. It's an exciting idea though!
Sounds like a blast to me...
 

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There was a while where I fretted about a Pinto event, I think there is a youtube of a mustang taking a rear hit and fuel blasting into the cockpit of a coupe through the rear deck speakers or something. I considered bolting my fuel tank in from under the car, never really checked to see if it was possible. I read that the issue is the tank comes into the car instead of going under it in a big collision. Tank armor does not fix this problem. But this is another mental exercise that never accumulated true momentum...


https://www.cbsnews.com/news/mustang-a-classic-danger/


Now after rereading this its got me thinking again - if I did anything, it would be removable.
 

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I do have a sheet metal divider plate screwed into place. It provides a great mounting point for my amplifier and I have a couple 8" subs mounted there also
 

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Discussion Starter #13
Thank you all for the replies. I know it won't be perfect fire protection. I'm also considering this for the stiffness increase, there's a guy who measured his torsional rigidity before and after mods and just screwing in a trunk separator added 14% to his total torsional rigidity.

I think I will probably hold off for now, get the car back together, and then add a screwed-in one later since it pretty much has to be removable anyway. I have enough on my plate at the moment, trying to get the car back together for a June road trip while working full-time.
 

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I say you wouldn't have a problem with or without it. I don't have a picture of my trunk at the moment, but it looks like mine has a piece of metal behind the rear seat itself. I also have no carpet in the back trunk. I had no problems when driving it around the neighborhood on Sunday. I would say go with what you think is best, but going without it would also be ok.
 

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This is one of those problems like "What if I was holding a jerry can full of gas, when lightning strikes me?"

Not saying that people don't get into wrecks, but honestly, you'd have to get REALLY gobsmacked before this would be a problem. If you're safety conscious, shoulder belts and decent headrests (to prevent whiplash) would rank far above a rear firewall.

However, there's more than one good reason to put one in - including the chassis stiffening, which is a very good thing.
 

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I installed one in my 69 Coupe & covered it on the interior side with Fat Mat. The panel came with sheet metal screws, but I bolted it in.

 

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I plan to make one for my 66 and I really like the rivnut idea. I'll have to dig out my aircraft hydraulic riveters and get some more rivnuts when I get there.

I see it this way you can sell it to some as a safety improvement that has the side effect of making the car stiffer and quieter or you can flip that around for the car guys.
 
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