RV-8 Cowl hinge pin

[tracy]

Gents, the hinge pin holding top and bottom cowls is a .090 wire and it broke in torsion do to tight fit. This was probably due to metal fatigue due to the welding of a 10/32 bolt to the end of pin. I have replaced the pin with a .089 by tapping it and bolt, then crimping and re taping bolt to screw into fastener, no weld. The pin now slides in nicely. The question is, will the 089" pin be ok instead of the .090" pin. Wondering if this will cause any vibration. Anyone had any luck reducing pin size?

[flyinga]

I'm not sure how the pin broke in "torsion." I don't think vibration will be a problem on the smaller wire as the cowling will be under slight pressure to "bow" it outward, thus keeping pressure on the wire in shear.

[tracy]

It broke while screwing it out.

[flyinga]

Got it! It must be tight if it broke in that manner.

[SHIPCHIEF]

I had tight pins on my cowl too. I use a drill to spin them while pushing in.
On the left cowl hinge assembly, I accidentally pinched one hinge eyelet. That made things worse. I had to repair it by shaping the end of the pin, and using it to re-drill the eyelet.
Now that I'm flying the pins install & remove easier. Probably vibrations etc. are loosening the fit of these pins, pretty soon they will be the same as the other RV's I've checked.
For now, I'd suggest you wipe the pins clean before installing them, and put a thin coat of anti-seize on the first 6" of the pin.
Yes, you will get black fingers, it's a mess.
As for using .089 pins, I see no reason why not. Just keep the .090 pins handy, soon after you start flying they might fit.

[David-aviator]

A scotch pad works great to clean the pins. Leaves them dry and sort of shiny.
Any dirt is gone.

I oiled them once on the -7A, never again. They weeped oil a long time.

In the beginning, like the genesis of pins in and out, light tapping with a hammer on a clamped vice grip works for me. After some flight time, they settled in, like make themselves at home, loosen up, and go much easier.

[Ron B]

Tracy

Door Ease lubricant available at hardware and NAPA stores works wonders on tight pins. No mess no fuss - just apply very lightly every time a pin is removed......