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Landing Gear Shock Struts


T Chamberlain
(@t-chamberlain)
Eminent Member
Joined: 16 years ago
Posts: 33
Topic starter  

Been awhile since I've used this forum so hope I'm doing it correctly.

My main landing gear is getting that splayed out look to the point that it is wearing out the inboard part of the tires much more quickly than the rest of the tire.  Besides rebuilding the shocks with new springs from Univair ($$$) I've heard that one can put spacers in the bottom of the cylinders to make up the difference in the reduction of length (or worn out springiness) of the worn out spring.  So, here are some questions.:

  1. Has anybody added spacers to rectify this problem?
  2. Does anybody make these spacers and if so where can they be obtained?
  3. How does one determine the thickness of the spacers required to bring the landing gear back into alignment?
  4. If I have to go to new springs from Univair, will they bring the gear back into alignment?

I rebuilt the right shock some 20 years ago when that spring broke into 3 pieces.  At the time I had a spring from a parted-out wrecked 108 that I used that seemed to work fine but now the problem has gotten too bad to ignore.  Any information on this problem would certainly be appreciated.

Terry


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Carsten H.
(@carl)
Trusted Member
Joined: 3 years ago
Posts: 81
 

Spacers are available at most hardware stores. Just large washers. Is it possible that what you perceive to be squatting is actually the result of a toe-out condition? I believe it is unlikely that both springs have sagged. One way to check is to roll the ship forward 10' and measure the distance between the wheels and then roll it backwards 10'. If no change it probably isn't an alignment issue. Gary Murdock had a technotes disc available ISC with a great discussion of how to deal with the struts including spacing. I'll copy it next time I'm at the hangar.


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Andrew Liebfried
(@aliebfriedearthlink-net)
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Joined: 1 year ago
Posts: 13
 

Just did mine, second time in 20 years. Both sides sagged same amount. Used tech info from this web site for detailed instructions. Yes check all the measurements, it may surprise you. I would suggest if you have springs of indeterminate age go with new.  The quad seal idea will help. If you have minor corrosion, polish piston shafts works well with quad seals. Major pitting needs chroming. Toe in is a fixed number and is work to correct. Make sure tail wheel spring is good. That’s in the sites tech data base as well. All this really makes landing and taxiing a 108 very nice.


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Dennis Crenshaw
Reputable Member
Joined: 16 years ago
Posts: 289
 

Terry, did you look at the discussion in hangar9aeroworks?   Look under Stinson 108 technical info--shock strut overhaul.


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T Chamberlain
(@t-chamberlain)
Eminent Member
Joined: 16 years ago
Posts: 33
Topic starter  

Dennis, thanks for the referral to the hangar9aeroworks web site. I haven't been to that site in years.  I was about to order springs from Univair because I couldn't figure out how much thickness of shims I'd need to bring the airplane back up to its normal stance.  But then the hangar 9 site provides not only what the length of the springs should be (along with great photos) but also the washers that can be used to bring the dimensions back up to the correct length.  A great savings of much $$$.

Also, thanks Andrew and Carsten, lots of good info. I appreciate all the help gents.


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Andrew Liebfried
(@aliebfriedearthlink-net)
Active Member
Joined: 1 year ago
Posts: 13
 

@t-chamberlain I made the mistake of ordering new springs. Two years later she was sagging. Pulled struts, measured them up added washers back-in business. Came apart a lot easier the second time.


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Dennis Crenshaw
Reputable Member
Joined: 16 years ago
Posts: 289
 

@t-chamberlain  Terry, my gear was not splayed before doing my shocks.  Also, they measured within spec, so I just added a minimum thickness washer.  I have no idea if my springs were original or not.  Airplane sits with normal stance, but the best part is the shocks don't leak!  Not a drop.  I think the quad seals do the trick.


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Dennis Crenshaw
Reputable Member
Joined: 16 years ago
Posts: 289
 

@t-chamberlain  Terry, the Hangar 9 website is a great resource, although it's dated now.  I was a good friend of John's and flew to his airstrip home several times.  He built a beautiful house and hangar, but was diagnosed with cancer during that building process.  He suffered a long decline and put up a mighty battle over about 9 years.  He had to sell his Stinson project, and his Chief, and then his Champ when he got to the point of not being able to fly.  I think the club is maintaining ($) the website now.   


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