Aluminum floors

I decided to make new floor panels out of 1/8" thick type 6061 aluminum panels.

The steel angle along the door side of the car turned out to be 5/8" higher than the flange along the tunnel. By placing a 1/4"x2" aluminum bar along the underside of the angle, placing the floor panel beneath that bar, and adding another length of bar stock beneath the floor panel the floor is leveled. Assembling with silicone caulking between each layer and bolting thru the entire sandwich with a series of 5/16" stn stl bolts fastened it. Along the tunnel, a layer of silicone and a lot of pop rivets completed it.

Across the rear, the VW floor support flange changes elevations; higher at the tunnel and lower at the outer end. Also, the corner areas are curved rather than 90 degrees. This required a transition piece in order to keep the overall floor flat and level.

Because the aluminum panels were not long enough to go front to back in one piece, 1" x 2-1/2" #16ga steel channels were fitted beneath the floor panel where the seam was made.

Just our of curiosity, why didn't you just buy new floor pans and weld them to the tunnel?

http://www.jbugs.com/store/merchant.mvc?Screen=CTGY&Category_Code=1081

ya - welding a steel pan half in place would make it much stronger than bolts, rivets and silicon. plus you wouldnt need to worry about leaks and rattles.

Or Lexan? That way you could watch the highway pass beneath you. Cover it up with carpets when it got distracting. With the top down and a transparent floor it would seem like flying every time you took it out for a spin.

OK, maybe more of a low level strafing run, but still . . .

Be careful about dissimilar metals causing deterioration. Can be an issue.

Larry... This was a very abbriviated kit, actually just a body, with no instructions, built in Mexico a number of years ago by a now defunct mfg. Although similar to other pan based Speedsters, there are many differences; mostly in frame dimensions. Using the old CMC manual was helpfull in some places, trouble in others; causing as many problems as it solved.

I originally purchased VW replacement floor pans but found that they were actually to narrow. Thought about other possabilities, and thought some alumium panels thatI happened to have might be a good solution.

With a thin coat of silicone between all of the various layers and seams, I have no doubt about the seams remaining water tight.

The 1/8" #6061 aluminum is considerably stiffer and stronger than typical "soft" aluminum, and the frame that is inside the body seems pretty substantial. I also have three steel channels beneath the floor; one under each seat mounting location and one forward of that.

I intend to put it on the road for a while before making carpeting, so if a change is needed, it shouldn't be difficult to go in another direction.

Time will tell. Wish me luck.

The dissimilar metal issue is only a problem if your car gets wet. You need 4 parts to have corrosion . You will have the anode(aluminum) the cathode( carbon steel) and the current ( 12vDC) . It need the electolite( water) to make it corrode. If you coat the alloy and steel you won't have to big of an issue.

I've seen a lot of RVs suffer from this problem and we all know our cars are completely water tight . . . I'm just saying.

Plus . . . All kinds of ways to get current where it shouldn't be and you don't need a lot to make it happen.

Just be aware of the issue and take precautions to keep it from being a problem.

I'm a big fan of the aluminum floor idea. Nice work, Brian!

Cory...Thanks for the compliment. Hope mine turns out half as good as yours.

Joe, Tom...Thanks for the input. As I said, every interface between any two metal surfaces was coated with a layer of silicone at assembly. I can't see water penetrating into those seams. At completion, I also intend undercoating with Rhino or a similar plastic spray on.

Regarding electrolisis; water would certainly promote and increase the corrosion process, but the two dissimilar metals (any two metals) in contact with one another, even when dry, creates dc voltage on it's own (thermocouples are an example). So even if kept absolutely dry, I expect some minor corrosion over a period of many years. I would expect that to eventually affect the rivets because they are the only place isolation with silicone was no doubt incomplete. If, in time, they become a concern, they could be easily drilled out and replaced.

Glad to hear you are using a coating. You are partially correct in regards to the electochemical reation. The instance you explain is a galvanic reaction . You need two dissimilar metals whih have different potentials ie aluminum ,carbon steel. With this combination the carbon steel would corrode to protect the aluminum. Now add DC current and you change everything (dependant of the polarity) . Its call impressed current. Now you make the aluminum corrode instead of the carbon steel. The aluminum will turn white and powdery where it is corroding. Riveted areas would fail first.
To eliminate the corrosion your first defense is a 100% efficent coating. The Rhino urethane-epoxy coating is excellent. Good choice.
I did not want you get to deep in depth in the aspects of corrosion defense. I deal with coatings, corrosion, cathodic protection systems on offshore platforms,buried pipelines, and ocean oil tankers.

Joe, thanks again. I work in instrumentation and controls, but have never been involved with cathodic protection. Appreciate all the info I can get.