Floor boards on new project

That's a lot like what the original 1952 -1955 Pre-A Speedsters had.

Drill through them into the lip that holds the metal floor pans in and secure them with sheetmetal screws.  Be neat with the spacing.  That's how the Pre-A cars did it.

If the lip is thick, you could use 10-24 screws, instead, but they'll be a pain to thread the holes for the machine screws.

I don't see any advantage to doing that - especially over a good OEM style steel floor.  Water/moisture will get trapped between the 2.  You are raising the seat an inch or so.  The original metal floor will direct any leaked water to a low area - where you can mop up or drill a hole.  Just use some sound deadener like DynaMat.  Sound like you had an old MGA at one time!

I agree with Greg. Considering the degree of waterproofness most of us achieve, we should assume the interior will periodically get wet. It will dry more quickly if there's nothing to trap the water and if there's a drain hole.

I POR15'ed my floorboards, added water and drilled through the low spots. Then I reapplied POR15 to the drilled areas, applied truck bed liner top and bottom, and then put rubber mat sound deadener on top. My car doesn't get wet often, but when it does, the rain just drains out and the interior dries quickly.

One other tip, don't worry about drilling the floorboards. Just treat them with a rust protective covering afterwards. I'm 5'11" and am glad that I'm sitting low enough that I don't have the wind in my face.

I second (3rd) Wolfgang and Michael. Those plywood bits look nicely made, but it's a bad idea to install them.

Having said that, if you must, put standoffs under them to make a gap between them and the steel, and then rustproof the steel and drill drain holes as @Michael Pickett describes. I made a "floating floor" ahead of the bulkhead on my Spyder (as is correct for a '55 Renn Sport 550) and painted all the parts of it with Pelucid before assembly, then painted the edges and re-coated with Spar urethane after assembly. Basically you've got to treat it like a marine installation.

(versus the real deal):

Everybody has an opinion, but mine is that unless you are under 5'6", you want the floors as low as they can be.

Thanks everyone, for  your time to reply to this and provide photos. I’m beginning to think these are a bad idea. I think I’ll cut the other one (I’ve bought the wood now) and hold off from fitting them for now, make a decision when the body arrives.
It certainly looks like I’ll be spending a lot of time on waterproofing in any case!

One last thing - does anyone have photos of the fitted seat brackets / runners and how they are fitted?

I do not have dropped floor pans for a taller driver, mostly because I'm 5' 6".

My first seats were from a Porsche 914 and I got the seats and the Porsche seat glides all together.  Mounted as they are in the car, they sit quite low, like the bottom cushion was even with the door sills.  

I decided to "upgrade" to cabriolet-style seats and for those I got a seat bracket and glide assembly from Speedway motors to keep the glides parallel:

https://www.speedwaymotors.com...and-Mounts,2432.html

And then modified the heck out of it to get everything to sit as low as possible.  There are a lot of seat glide options out there at Speedway, Summit Motors and others, just search on seat glides or seat brackets or such.

@SteveMarson. Let’s not get too hasty, here.  There are some things to consider (like water intrusion), but the precedent here is that virtually ALL of the 356 Pre-A cars had plywood floors.  They also had 2-gauge dashes, but that’s another whole thread and a BIG DEAL if you want to go that route.

True, there was a metal floor under the plywood on 356 Pre-A cars (before 1956) and they dropped the plywood floor on the A version in 1956 (while keeping the angled plywood under the pedals and over on the passenger side for comfort), probably because it was a pain in the butt to maintain, but it gave a very flat floor surface for the ubiquitous Porsche 356 rubber floor mats to lie upon.  Were you anticipating using plywood in place of metal floors (you probably should re-think that), or on top of metal floors to level things out ( which has it’s own set of issues, as the floor suddenly drops a bit when it gets to the seats) ?

Anyway, “it’s your car, and you can do what you want”, just like Eric Burdon and the Animals, before he got weird.

Gordon - The floors were intended as extra to the metal floors (new pans) to level things out as you say. The jury’s out, as they say. Decisions, decisions!!

You do need the seat tracks level and parallel - if using seat tracks.  You may also just attach the seat in a fixed position (if only you or someone your size drives).  Either way washers or wood spacers can be used to ensure level.  After installing the carpet, you might have to use a strip of mahogany/oak so runners clear carpet.

Water is not your friend here. Unless you are really a fair weather driver, you will have water.  Clean metal pan, red rustoleum, couple of coats, truck bed liner, couple of coats, cocoa mats.  I use some of that rubberized mesh stuff that you can put under throw rugs to keep them from sliding.  Cheap and easy to replace. I have not drilled any drain holes, but I hear this is effective,  Count on taking whatever you put in there out and putting it in the sun to dry.  Seriously.  Cocoa mats work really well, and have become a standard, although clearly not OEM.

Not a great pic, as shows the cocoa mat only on right side.

Better pic. I do use the polyester carpet inserts that came with the car.  Again, they come out and can be dried in the sun.  For cocoa, you make a paper/cardboard form that fits in the space like you want it to, mail that off to the company, and they send you the mats in due time.