What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Shimming the WD-409 Tail Spring Weldment RV-7

aeroaddict

Well Known Member
Finally have a decent fit between the F-711/712 and WD-409. I ended up with a 0.090" shim to get a decent fit between both bulkheads and the WD-409.

Before I start riveting everything together, I was just curious what others have experienced; shim or no shim? Am I missing something?

Also, the WD-409 was not in the best of shape. The flanges were not parallel so I have to do a little hand finishing to have everything fit.
 
shim

The original builder of my a/c, an RV8, did not take too much care in this fitment. Really warped things when he bolted it together. I fussed with it for days, then broke down and bought new rear bulkheads. It fits pretty close now. I, too, had to message the weldment a bit to get things to fit. When I called Vans they suggested that shimming was pretty common.

One suggestion from a friend helped a lot. If the pre existing holes in the weldment are an issue, just weld them up, grind flat and re-drill. I wish we could do that with aluminum?.
 
.040 shim for me. Epoxied it in to position. Dan, predrill your keeper rivet holes in your 712 bulkhead but not through the weldment. When you finally rivet on the F-714 aft deck after determining that you have no twist in the fuselage then final drill the keeper holes. You will have good access through the inspection openings to buck those rivets. Hope this helps you.

DSCN1085.JPG

DSCN1090.JPG
 
Last edited:
Shimming is pretty common. Between the weldment not being "perfect" and the bulkheads in that area not being flat, it's usually going to need a little work. And as Longline said, Vans will tell you the same thing. It's all part of the joy and frustration of building that Van has referred to. :D
 
Thanks All

I was just concerned that my 0.090" shim seemed excessive. But I wanted to ensure a decent fit between F-712 & WD-409 for the future HS install.

ABC; good advice. While I did drill bulkhead and flange for the keeper rivets, I did so after ensuring the fuss had no twist (installed the aft top skin to remove twist). And it all lines up nicely, BUT I think I will not rivet the 'keepers' until later as you suggested.

Cheers
 
Last edited:
Back
Top