Penthouse resurrection

[boywonder]

The aluminum angle may be problematic due to the compound curvature of the roof.......then again..maybe not....



I think member AndrewST put an EB penthouse on an RB van...but you are going the other way.......


bemerritt did a roof install.....starting around here in his build thread:


http://www.sportsmobileforum.com/for...-15158-18.html

[86Scotty]

I've seen a few RB/EB tops on opposite vans in the early days of the forum. Perhaps DaveB or Herb (Broncohauler) can remember who did them other than AndrewST.

As for your canvas attachment idea, just about anything will be an improvement on the firring strips SMB uses. I've removed and replaced several and they're always rotten and falling to pieces. Use SS screws if you can. Regular ones will see enough moisture there to turn to rust by the time you need to remove them.

[Orv]

Data point: Volvo 240s used aluminum rear bumpers bolted to steel brackets with steel bolts. I had one of them in a state that used lots of road salt. It did eventually suffer from galvanic corrosion, to the point that it became brittle around the brackets and fractured. However, that was in a situation where it was drenched in salt water for half the year, and it took about 15 years and a couple taps from parking-by-braille incidents for a problem to show up.

I've had lots of cars with aluminum engine blocks with all kinds of steel hardware bolted to them, though, with no corrosion issues. Depending on how wet the area is it might be fine.

[michal740]

The dissimilar metal issue is something to think of for sure. I don't think it's going to be major issue since the aluminum frame will be boltet to painted surface and will have butyl sealant between them. I may be wrong.
Another thing is the climate here is extremely dry for most of the year,so I think it will hold up ok. Likely leave the top unlocked and supported by small 1 inch blocks to alow air ventilation when it is going to be parked for some time.

[Pntyrmvr]

There is still the steel screws touching both the angle and the roof.

How about a plastic strip to replace the factory plywood strip? A chunk of plastic 3/8” x 2” would be the perfect inert way to hold down the canvas. Steel screws with a washer would do the attaching through to the sheet metal.

Plastic like a thin cutting board is made out of.

[86Scotty]

Let's keep talking about galvanic corrosion. I just love to say it. It's fun. It'd be a great name for a death metal band.

[Pntyrmvr]

Band members referred to as Galvanics?

[Pntyrmvr]

Groupies known as Electrolytes?

[Orv]

Originally Posted by michal740

The dissimilar metal issue is something to think of for sure. I don't think it's going to be major issue since the aluminum frame will be boltet to painted surface and will have butyl sealant between them. I may be wrong.

I suspect you're right. I'd also use some anti-seize on the bolts, just on general principle.

Galvanic corrosion by definition requires electricity to flow -- the dissimilar metals create a battery. It requires some kind of conductive liquid as an electrolyte (salt water, say) and a path for electric current. The paint and butyl are both insulators.

[michal740]

Agree Orv,
I have seen some some companies to bolt aluminum frames (not necessary roof tops)
to steel bodies and didn't really use anything special in terms of materials.
Stainless steel screws and butyl or rubber seal should be ok. Time will tell.
I will look if I can find plastic frame material as Pntyrmvr suggested. May even be easier
to fabricate round corners.
Top is going up on the 22nd.