[BruceMe]

I built my rv-4 as fastback. The frame is 100% custom. I tried building it out of aluminum, but it cracked from vibration and normal wear & tare. Is there anyone with the finish kit in the garage that can describe what Vans builds the stock frame from? Is it cro-moly? If so what thicknesses? I'd greatly appreciate it, I'll run over to AirParts (I live in KC) and start fabricating the replacement this week.

Thanks

-Bruce

 

[Russ McCutcheon]

Aluminum

All the Rv-4 frames I have seen are aluminum, I don?t know the alloy, I think the RV-8 is 4130 so you can probably use whatever you want. I would find out what the speck is for the aluminum and stick to that, probably lighter.

 

[Special Delivery]

Data point... for certain, on the RV-3 the bows are 3/4" square 5052 x .063 and the rails are 3/4" 6061 T6 angle.

 

[RBD]

According the drawings I have for the RV-4 canopy:

The bows are 3/4" 6063-T52 square tubes (.062 wall thickness)
Rails are 3/4" 6061-T6 angle
And the tubing that the bubble is riveted to is made of 7/16" x .035 6061-T6 tubing

 

[BruceMe]

thx all... the aluminum is a problem, it fatigues and cracks very easily where it has to make different bends than the bubble. And at the back end, the canopy is basically wide open and bows in/out very easily, this causes additional fatigue cracking. I'd prefer to go with steal and eat a little weight. I'm already 914lbs, I can afford another pound if it makes the canopy stay on.

-Bruce