by Chappy » Mon Dec 15, 2008 1:23 am
Tony,
I finally found my mis-located notes today from when I built my series 1 Lazair in early 1980. The T26 Pushrods supplied with my kit were 0.250 OD X .049 wall X 117.25" long each, made from 6061-T6 aluminum tubing . I don't remember having to trim the length. Do not substitute a softer, weaker 5000 series aluminum for the high temper 6061-T6!
The tubing needs to be well lubricated where it runs through the nylon guides, as they get brittle with age and binding could cause them to fail. Unfortunately, the lube will pick up dirt and grit that will cause not only wear on the guides, but also on the tubing. Clean the old lube off and redo it to keep them clean depending on how dusty your area is.
The larger aileron pushrods used nylon insets that were threaded for rod-end bearings. The inserts are Pop riveted in place. The expanded bulb of the rivets can eventually crack the inserts causing them to fail, and allowing them to pull out of the tubing. I suggest giving them a pull to check, or replace them with aluminum inserts like later Lazairs used. (Incidentally, very early series ones didn't come with aileron pushrod tubes in the wings, they used dual cables.)
Also, you might consider upgrading the T-26 tubes to the 1/2" pushrod setup used on later Lazairs.
Chappy