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I'm assembling the landing gear struts. The bronze cap is extremely tight to where I can't slide it down onto the piston rod. Is this normal? What is a proper fit and what can I do to make it fit correctly?
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If it will not slide down then there a couple things that could be done. Either open up the I.D. of the bronze top cap a couple thousandths, or alternately polish down the O.D. of the 3/4" piston tube. Have you tried with a little grease or lubricant? Mark -
Seems like I had trouble with this, also, and wound up using some very fine wet/dry sandpaper (did I mention VERY fine?) to very slighly chamfer the edge of the bronze cap (both inside and outside edges, along with the "groove" for the rubber o-ring. This was to allow the edges to ease past each other just a tiny bit. Then I used my drill press as a manual press to lightly push the components together with a good bit of hydraulic fluid as lubricant. I used very light pressure, applied evenly (thus the drill press use) and I think was the trick, along with the lightly chamfered edges. First strut took me about 3 days of puttering in the shop to assemble. Second one took less than 4 hours total. If I did it again, I'd guess around 2 hours total. It's a steep learning curve for us newbies!Jim Parker
Farmersville, TX (NE of Dallas)
RANS S-6ES (E-LSA) with Rotax 912ULS (100 HP)Comment
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I used fine emery cloth on the piston tube. It took very little polishing to get it right.Scratch Built 4-place Bearhawk. Continental IO-360, 88" C203 McCauley prop.Comment
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Thanks for the ideas. Pretty much what I've been doing. I have been using some valve grinding compound coupled with scotch brite pad working on the piston tube. Seems to be polishing up the piston tube well but the bronze cap is still tight. I apparently need to be more patient and keep at it.Comment
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Bill, have you put a dial caliper on the O.D. of the piston shaft and the I.D. of the bronze top cap? That will tell you what you are looking at in terms of what might need to be removed. I bet it is just 1 or 2 thousandths.Mark -
Also - the heavy die spring has 2.5" of travel to when it gets hard/solid. So if you are polishing the piston shaft make sure you go down that far. Mark
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I had the same issue. I found that the piston shaft wasn't exactly round. So, I started with fine scotch-brite on the piston shaft until I could get the bronze cap to go on a little bit. After I could get the cap to go on a little bit, it would change the coloration of the shaft on the high spots due to the tight fit with the cap. The high spots ran length wise, so I'd spend my time with the scotch-brite on those high spots. Then repeat. At some point I stopped doing it by hand and put a scotch-brite wheel on my drill press to speed things up. Be careful if you do that though, sneak up on it. You don't want to take too much off.
Mine did take a fair amount of polishing. Eventually, it all fit very well, snug and even. Good luck! Keep at it, it will fit.Comment
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The O.D. of the Shaft was .753 the I.D. of the bronze cap was .748. I used a 3/4" spiral flute to open up the bronze cap slightly. Took 5 minutes to do both of them and they slid down on the shaft perfectly. I first tried a 3/4" straight flute but it didn't open up the cap at all.Comment
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