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MG MGA - Aluminum Floorboards

In preparation for installation of a new carpet kit, I pulled out the old carpet and discovered totally oil soaked 3/16" plywood over 1/4" sheet aluminum (labeled "Martin Marietta"!)
Are the aluminum boards a good thing? Is there a need for plywood over them?
Thanks for all input.
Steven B

Well Steve, you should know that Martin Marietta is a very reputable company with a long history in aviation and aerospace. Your aluminum floorboards are quite a bit more expensive than any old plywood floorboards, and if in good shape, unless you are looking to make a concours car, shouldn't need replacement. The major cause for concern with aluminum floorboards is whether galvanic corrosion has caused them to corrode excessively, where they might need replacement. As for the plywood, I might replace them with new, non-oil impregnated wood if I were you, but that is your choice.

On a serious note, If you decide to keep the aluminum, the main advantage of the plywood is noise and heat reduction in the car.
Mike Parker

Thanks Mike - I was wondering which space shuttle is missing some parts!

I guess the wood would also be good for attaching lift the dot fasteners but then it would have to be 1/4" I'd think.
Steven B

Steven,
I was going to mention something about the space shuttle- glad to know you already contacted NASA about it. Hey, maybe they will make that little MG fly!
Mike Parker

I live relatively close to Boeing Surplus and they are an Aladdin's cave of cool bits and pieces. I would think that your floorboards came from Martin's version of the place.
I have often wondered if phenolic honeycomb panels could be found to replace MGA floorboards. Light, insular and fuelproof...Hmmm. Have to check at Boeing next time I am south of Seattle.

Rich

BTW: I certainly agree with Mike on the propensity for galvanic corrosion.
Rich McKIe

Funny, I spoke with a buddy that works at Lockheed/Martin just the other day and he said that they have been looking for a important piece of 4x8 alu since the mid 70's. He said "it even has our name on it". Apparently this is a piece left over from the SkyLab project and is not stable. May be responsible for SkyLab's early departure into our atmosphere...

JohnB

Is there any way to avoid the galvanic corrosion, like inducing a small electical charge to the aluminum plates?
Steven B

Modified MGA Racers in the UK use aluminium floorboards, fibreglass panels and anything that will keep the weight off. I would avoid corrosion (and leaks!) by putting some kind of sealing strip between the chassis and the aluminium.

John.
John Prewer

Gentlemen,
While the concern about galvanic corrosion is understandable I'd like to point out that there are numerous place in our MG's (doors, bonnet, boot lid) where aluminum and steel have peacefully co-existed for years with no apparent protection between them.
Cheers,
GTF
G. Foster

Steven,

When I was restoring my '59 roadster I cut new plywood and cut 16 guage aluminum plates to attach to the bottom of the plywood. I then powdercoated the aluminum and glued them to the plywood before installing them with a flexible rope caulk between the frame and floors. As I read this over it sounds a little fanatical but I got the aluminum free and powdercoated the pieces in my garage wall oven so it was pretty easy.

Randy Myers
'59 roadster, coupe
Randy

I can't let you guys across the pond get away Lockheed Martin, Boeing and Martin Marietta - aircraft quality aluminum without at least one example of British supersonic fighter jet fighter aircraft quality aluminum - might be some titanium in there as well!

The rear panel on my MGPA 4-Seater was made by a British Aerospace (as was - now BAE Systems) apprentice many years ago for a crate of beer.

Picture attached (PA on the left and TC on the right).

Steve


Steve Gyles

Very nice Steve!
I worked for Canadian Pacific Airlines back in the early 80's and the BGT that I owned at the time had a considerable amount of aircraft aluminum, latches, Cherrymax rivets etc. incorporated into the car. It was nice to have the facilities to fabricate parts at my disposal. Sadly the company is now long-defunct so that source of parts is no longer available.

Cheers,
Rich
Rich McKIe

>While the concern about galvanic corrosion is
>understandable I'd like to point out that there are
>numerous place in our MG's (doors, bonnet, boot lid)
>where aluminum and steel have peacefully co-existed for
>years with no apparent protection between them.

Well, there is aluminum, and then there is aluminum. Most aircraft aluminum is alloyed with other metals such as copper, magnesium, or zinc (and others). These alloys are far more susceptible to corrosion than other commercial alloys, since they are capable of galvanic corrosion, without any other metal being present. A combination of persistent dampness, poor protection (priming, sealing, etc), difficult to clean surfaces and time are a sure recipe for turning your metal into a white, powdery substance. A good place to find those sort of conditions might be between your floorboards and frame.

For my floorboards, I am thinking of sticking with tried and true plywood, encapsulated in epoxy resin and with a thin layer of fiberglass cloth top and bottom. If you wanted to get ultra fancy, you could substitute a thin (say, 1/4") foam core between your layers of glass, adding carbon reinforcement, and hard points as necessary for mounting the seats. But plywood should be sufficient.

If you want to use aluminum, I would stick with one of the marine grades such as 5052, or use 6061T6, which is a more corrosion resistant aircraft alloy. But it would be a lot of expense for very little benefit.
Del Rawlins

Thanks for all the great comments. I THINK the aluminum is 5051, hard to read the blue lettering/numbering on the plates as it was rubbed off a lot.
Should this be strong enough to use without the extra 1/4" of plywood on top - which doesn't seem to me to add much to the strength. I ask because if I am going to cut plywood I might as well get the 1/2" marine or exterior grade, polyurethane it and use it rather than messing around with aluminum AND plywood.
Steve
Steven B

According to one MGA racer, plain aluminum floors are just too hot for daily street use. His car only sees short sprints and the cockpit temps are high. The wood acts as an insulator against the exhaust heat, the aluminum panel just adds to help reflect that heat away. I'd stick with the wood floors.
Bill Young

Anyone know of Aluminum floors for sale? Kind of hard to have some one make them up. Doug Jackson use to have a set, but has sold much of his stock.
ASH Andrew

If you can get it, I would have thought that aluminium honey comb section would be best. It's lighter and stronger than plain Al and would probably add a little heat insulation too. I'm not sure how to tackle the galvanic aspect, possibly a plastic membrane between floor and the frame and tubes to protect the screws.
Dan Smithers

Andrew -
Mine may be available. I am not going to race the car and, as stated above, not sure I want to mess with wood over aluminum when 1/2" ply is plenty strong and cooler.
Shipping might be a problem, we are at opposite ends of the country.
Steve
Steven B

Andrew- it is very easy to make up a set. Using the originals as a pattern. I cut up 3/16ths alu using a fine tooth carbide tipped blade in my circular saw. It's loud and makes a heck of a mess but cuts like butter. Place the alu on a piece of plywood, drop the blade 1/8" lower than the thickness of the alu and your set. If you go slow you can cut gentle curves.

j

JohnB

Steve. Let me know how much you would want for the Aluminum floor boards. My E-Mail is
carndrew@aol.com
ASH Andrew

This thread was discussed between 07/08/2007 and 11/08/2007

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