Attaching 5086 panels to 4130 spaceframe

[drysump]

I'm building a one-off street car with a 4130 steel
spaceframe skinned with riveted 5086 Al panels,
including the wheel well slashguards and floorpan.

I am concerned with corrosion and leaks. This car
will be driven in rain and slush and will likely
spend most of its life within a mile of the Pacific
Ocean.

Specifically in regards to preventing corrosion,
galvanic and otherwise, what are the best practices
for prepping the 4130 and 5086, rivet selection,
and seam sealing?

Regards
-Tom

 

[YLWEA]

I suspect you might get some good information talking to aviation guys. Riveted aluminum/steel connections in potentially corrosive environments sounds like an issue commonly addressed in aviation constuction and maintenance. I believe they have primers/paints (possibly chromates?)they routinely coat internal spaces with to minimize corrosion. Not sure how they effectively seal reveted connections. Sorry I can't be more help, but then again no one else seems to be responding with useful guidance, either.

 

[swall]

From a galvanic corrosion standpoint, you are not in too bad a shape.The worst galvanic couple is a small anode and large cathode, as the anodic portion of the couple will be rapidly corroded.The best situation is a large anode and small cathode.The corrosion of the anodic portion of the couple will be minimized.With your combination, you are more close to the latter than the former.As you will undoubtedly be painting the spaceframe, you will further reduce the size of the cathode.To fasten the 5086 aluminum panels to the frame, zinc plated steel rivets would work OK. Rivets coated with an organic zinc rich coating, such as Dacromet, would be even better.To seal the wheel well areas, I would use some of the flexible automotive "chip guard" paints used on rocker panels.Visit an automotive paint store for ideas there, as well as primers and pretreatments for aluminum.One source of aircraft paints, rivets and other supplies is Wicks.There is another source called Aircraft Spruce, I belive.You can spend hours on a rainy day going through their catalogs.