Center brace attachement

goanddo · #1 07-09-2018, 06:32 PM

I just want to say up front THANK YOU to people who generously share their knowledge. I really am very grateful.

The Center cabin brace is attached to the cabin top with four screws (MS24694S72) and four spacers made from aluminum tube (AT6-058X5/16).

Here is the part I am having trouble with, the head of the screw is almost the same diameter as the spacer which is the diameter of the hole.

Screw head Diameter .351
Spacer Diameter .312
Hole diameter 5/16 .312

How does this setup hold the brace securely? Surly, I am completely missing something? Can someone please set me straight?

Thank you! Thank you!

Ron

Electrogunner · #2 07-09-2018, 06:51 PM

Check the hardware call out again. I seem to remember the head of the bolt being a larger diameter. The spacer material is correct.

Lynnb · #3 07-10-2018, 06:46 AM

FYI, your pictures are not showing up.

flion · #4 07-10-2018, 08:01 AM

The screw head was slightly larger but I wasn't happy with the arrangement, so I chucked the spacers in a drill press and used a triangle file to make a couple of very shallow notches in the spacer and then roughed the remainder of the surface up. I then glued the spacers in, with a generous amount of epoxy and flox in the space inside the cabin top in that area. There was nothing in the instructions about gluing them in but the company often does not give explicit instructions about common procedures.

ppilotmike · #5 07-10-2018, 08:59 AM

..Has anybody used washers or something under the heads of the screws? I seem to recall seeing an airplane with tinnerman (?sp) washers under the heads to better support the loads..

BobTurner · #6 07-10-2018, 01:34 PM

IMHO the brace is mostly for roll over protection, when the screw will be mostly in shear and maybe compression. Forces on the small lip of the screw head should be small. I think Vans? engineering gave some thought to this design.

lr172 · #7 07-10-2018, 02:57 PM

You install the al spacer flush or a bit proud of the f/g and then countersink. The 100* countersink will transition from the fiberglass and into the spacer. That countersink angle will allow the screw head to properly apply compression/tension on spacer once tightened. I wouldn't modify this, as it seems to work properly.

Larry