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PostPosted: Mon Nov 14, 2005 12:41 pm
by uscgairdale
I have been making significant progress on my fuselage restoration, but I did find a cracked bushing. I believe that it may be the same part number as the B7 bushing on the series III. The Lazair II uses five of these total on the fuse. If I can find some or a suitable replacement, I'd like to change all of them.

Does anyone have any? Perhaps Tyler? I know that you have spare bushings for rudder pedals, I thought that maybe you could enlighten me.


PostPosted: Mon Nov 14, 2005 1:27 pm
by JPXman
ah the B7 bushing

this is the same bushing that the torque tube on a single seater runs through before it enters the mixer. my best buddy myles was my saviour with this bushing!

I had a sheet of teflon, and myles took it to the machine shop and carved out a brand new bushing for me! too easy. think of doing that option, especially if you want 5 of them.

they also sell rods of teflon in that diameter, and you could get a shop to drill down the centre and slice them up for you!

my dream is to someday make a complete bushing kit for the lazair, we'll see what happens...


PS: in this pic is the one we made - it is hand carved with a dremmel tool because i made the new one about 3 times as thick as it was, but after trying to put everything back together again realized that it was that thickness for a reason :) i was able to leave a little bit of beef at the lower end there, as that's where mine had cracked.

PostPosted: Mon Nov 14, 2005 1:29 pm
by JPXman
and this was Shannon's FAR more eloquent mod to increase the bearing surface area on the torque tube. i got this pic 2 weeks after my mod :) better late than never!

PostPosted: Mon Nov 14, 2005 3:36 pm
by ozzie
i notice in my series one assembly manual that 2 B7's are used here like in the above photo. maybe there was an error in the series two manual. OZZIE

PostPosted: Mon Nov 14, 2005 9:26 pm
by Shannon
According to the Series II manual two B-7's are to be installed (top&bottom) on the fitting F-20.

PostPosted: Tue Nov 15, 2005 9:32 am
by russell
My series 1 came with only one nylon donut bushing. I found that after a short time this caused considerable wear on the tube to the point that any further wear could lead to a catastrophic failure of the entire control system. I augmented this design with a small caged needle bearing which included a steel inner sleeve.


PostPosted: Tue Nov 15, 2005 6:58 pm
by uscgairdale
Cool. I was pretty sure that it was a B7 bushing. I like the idea of doubling up on them as well. My old man is a gifted machinist and he's going to make some for me out of some 1/4" nylon sheet that he already has. It should be an easy job, but he's already got the material, not to mention stuff like a lathe and milling machine.

I am making good progress so far. Everything in the previous picture is cleaning up real nice except for the 1" angle that's part of the forward wing attach point. There had been a field mouse nest up near the mixing unit and all of the animal waste collected on that angle piece. That waste corroded almost halfway through the aluminum! Needless to say, I replaced that piece with a new one.


PostPosted: Wed Nov 16, 2005 8:20 am
by Shannon
Series II B-7 arrangement on F-20.

PostPosted: Wed Nov 16, 2005 6:23 pm
by tommyb
my 2 cents again, it might be worth it to have your dad make some extrta since other people are going to need them too. i dont have a lazair yet but i might be persuaded to buy some extra parts that i are known to wear.

PostPosted: Fri Nov 18, 2005 5:28 pm
by uscgairdale
My dad is going to make some extra ones. It really isn't a difficult piece to manufacture, the only reason that I didn't make it myself is that I don't already have a 7/8" bit to drill out the stock. In my case, wear wasn't an issue, part of the bushing had cracked near a rivet hole.