THe steel decklid for my 31 Plymouth coupe is missing all the wood bracing, hinges and latch. And it weighs 25 pounds without all that stuff. So I was anticipating a bunch of work to install it. But then I started thinking about fabbing one out of aluminum and mounting it with 4 pins or dzus fasteners.

What thickness and type of aluminum would be the best to use? Light as possible, but still strong enough.

All suggestions are appreciated! THanks, Joel

I would use 6061T6.. about .040 max.. its
tough but will hold the shape once you get
it rolled
EDIT
Joel.. will you have access to a english wheel..
that has very little compound roll to it... 6061t6
is tough.. it doesnt like to bend tight 90* bends
but I'm talking tight.. on the edges I would weld
a lip to it instead of folding it over.. I'm sure
you know you have to have ribs on it... I have used
a engish wheel on 6061T6 and it worked well... I have
used other alum material for different forming work
like intake runner on tunnel ram but it was much softer

Nice project

You wont do it with a flat sheet alone, You will need to fabricate some ribs and formers to keep its shape. I would look at 2024t3 .020 for the skin and 5052-O or 3003H-14 to make your structure from. If you need a compound curve, 5052 for all of it. The 5052 is weldable and formable. If you want to get fancy, form it and have it heat treated to create stiffness. You can also have it anodized. Tim

THanks very much! I'll look into that stuff. I don't have acces to an English wheel. I was thinking I'd run it through a roller.

Or what if I could bend some angle to form the edges, then bend the sheet over the angle and adhere it? Then run some up-down ribs with a bead roller?

HJ
You're in good hands here as far as the advise you have received so far.
I've used both 2024 and 3003 aluminum sheet to make almost anything.
As you may have seen, I made my hood and the underpinning skeletal from the same material. Light and might. But you will need several special tools, (English wheel power hammer, dollies) or a buddy that may have a shop like I did.
Your deck lid should be a cinch though. Good luck and it looks very good already.
Love those Tin Lizzies from the BC.

Make it easy for a trunk monkey on DW to exit out of efficiently.Initals JB come to mind.LOL

Make it easy for a trunk monkey on DW to exit out of efficiently.Initals JB come to mind.LOL

Need a shrinker to get the curve on your bend, you could do a wire edge, but you will still need structure to support the sheet. You can look at metalmeet.com for some advice. Tim

nice car joel ! looks good !

We have done roof inserts and trunk lids with .045 and .060 aluminium and eliminate a lot of structural bracing.

Wait a minute... What happened to the second Kirkey seat?

rumble seat?

You get an upside down milk crate.

I did that, its a [censored] when you roll off of it backwards!

Not as bad as sitting on an upside down 5 gallon bucket driving a 500 horse 4 speed car. DAMHIK.

You could use the steel one to make a mold and build a fiberglass lid. Or have a fabricator shore up the lid with metal and maybe punch some louvers in it. Whatever you do, that is a cool project car.

IF he could borrow a lid from someone for a day
or two he could take a mold off of it for a glass
lid
EDIT
He could do a mold and make it out of carbon fiber
like I did for my hood... if he wants LIGHT.. way
lighter than alum or fiberglass and its easy to do

I do have the steel lid. It is missing all of the wood structure, so it is just the steel skin. It weighs 25 pounds. How much would a glass replica weigh? I was thinking I could get an aluminum one down to about 7 pounds if I used .032 or thinner

I'm glad you guys like the car. It has been a long-term dream of mine to build a hot rod like this.

If it weighs 25 Lbs just as it sits without the wood structure then it would probably weigh 35 pounds or so originally.
I would say that a glass one with all the webbing and structure to make it functional without being too fragile may not be much lighter than 25 Lbs. It may be at 15 or so. Aluminum may be at 10-12 Lbs and carbon be the lightest at maybe the 8-11 lbs. maybe even lighter.