.032 upper cowl hinge shim question.

From what I can see the .020 X 1/2 inch shim material is used between the firewall lip and the cowl hinges. There is a note on detail F on page 45 of the cowl instructions that says to use a .032 shim. Is the shim for the whole top hinge supposed to be .032 instead of the .020 or is the .032 just in the curved area coming down each side. If that's the case it doesn't show where to transition to the .020 shim. I haven't found any .032 X 1/2 inch shim material either. This is on an RV-9A BTW. Thanks in advance.

Trial and error...

The shims are used to try to mate up the thickness of the skin with that of the cowling. However, the cowling thickness can vary and each fit up is a little different. The smaller diameter hinge pin that gets used to allow the bend around the corner allows the cowl to move around (others have tapered their pins to avoid this issue). Regardless, it is my opinion that you shim to fit after you have drilled and fit your cowling. There is plenty of tolerance there for an .032, .025...whatever works for your best fit.
I think this is why the instructions are vague.

So then I should just leave the hinge clecoed to the firewall until I get the fit like I want it so I can change the thickness of the shim before I rivet it on? Anyone else find any .032 X 1/2 inch wide material in their finish kit?

Yes, that is my opinion.

rv9aviator said:

So then I should just leave the hinge clecoed to the firewall until I get the fit like I want it so I can change the thickness of the shim before I rivet it on? Anyone else find any .032 X 1/2 inch wide material in their finish kit?

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That is what I did with my 6 and I believe the cowling/firewall interface is common to all side by side models.

Thanks for the help. I appreciate it. Anyone else have any thoughts on the subject?

rv9aviator said:

So then I should just leave the hinge clecoed to the firewall until I get the fit like I want it so I can change the thickness of the shim before I rivet it on? Anyone else find any .032 X 1/2 inch wide material in their finish kit?

Click to expand...

I am building a 7 and have also been searching for some .032 X 1/2 wide material for the same purpose. I didn't find any but I did find a piece of .032 X 1 X 48. The packing list gives a discription for this piece as ALUM STIP C-653 so I assume it goes to something else.

It's been almost 3 years since I did my 9A (green) cowl. I do not remember any discrepancies about .020 vs .032 shims. I just went with what was on the drawing. VAF posts from back then debated even using hinge shims at all.