View Single Post
Old 02-17-2018, 10:56 AM
rvbuilder2002 rvbuilder2002 is offline
Join Date: Jul 2005
Location: Hubbard Oregon
Posts: 8,156

Originally Posted by iamtheari View Post
I finally got the back ordered parts from the empennage kit today. There was a note in the hardware bag #1902, which said that the MD36-14M rod end bearings were replaced with MM-3M-42. These appear to fit just fine. However, there was not a note about the MD36-16M rod end bearing, which is for the bottom of the rudder. It was replaced in my kit with a GMM-3M-680. The thread of the rod is correct, and it is slightly longer than the MM-3M-42s, but it is significantly thicker and does not readily squeeze in between the hinge brackets on the vertical stabilizer.

The MM-3M-42 housing is 0.333 thick and the bearing is 0.434 thick at the flat faces where it will mount.

The GMM-3M-680 housing is 0.377 thick and the bearing is 0.500 thick at the flat faces.

The hinge brackets on my vertical stabilizer have 0.439, 0.459, and 0.409 clearance between them (top to bottom). The MM-3M-42 bearing fits perfectly well in all three, a little tight in the bottom one. The GMM-3M-680 is a problem.

Should I find a replacement for the bottom rod end bearing or force the GMM-3M-680 into place?
Originally Posted by iamtheari View Post
I wrote to Van's this morning and will hope to get a reply. However, I found some specs that make it look like the replacement part and the original part are a good match, 0.5" wide at the bearing. Did anyone else have any issues with the lower rudder rod end bearing fitting between the hinge brackets on the vertical stabilizer? If it's just a tight fit and that's okay, I won't worry so much, but I don't like having to apply a lot of force to anything without triple-checking beforehand.
Because of your VAF post, and because an alternate part was recently introduced, this was looked at by engineering.

The rod end bearing used at the bottom position of all RV models has always been larger overall, because a longer length is needed (a longer length is not available in the sized used at the other two positions).

The new part that you received does match the original size specs (as you already found).
The problem must be related to your lower hinge brackets.

By design, they are supposed to be further apart that the upper ones to allow for the fit of the wider bearing.

The first thing to check would be that the bend on each is 90 degrees. If they are under bent slightly, the resulting gap will be smaller than intended.
Any opinions expressed in this message are my own and not necessarily those of my employer.

Scott McDaniels
Hubbard, Oregon
RV-6A (aka "Junkyard Special ")
Reply With Quote