1948 170 Tailwheel Bushing Replacement

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1948 170 Tailwheel Bushing Replacement

Postby chrishartis » Wed Feb 26, 2020 1:58 am

Hello,

While servicing the tailwheel springs I noticed that the bushing that holds the front of the springs has been warped and bent. It looks to me like it’s made out of aluminum, but when I look the part up in the parts catalog it says that this piece is supposed to be rubber? Can anyone tell me what the correct part number is that I should be looking for or should I just make a rubber bushing? Curious as to what the best solution is for this part... thank you in advance!

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Re: 1948 170 Tailwheel Bushing Replacement

Postby gahorn » Wed Feb 26, 2020 2:48 am

Bushing PN 0542109 is made of rubber, per the IPC.

A short search of the usual sources does not find one in stock anywhere. You might try to make one out of hard rubber or hose.
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Re: 1948 170 Tailwheel Bushing Replacement

Postby c170b53 » Wed Feb 26, 2020 3:11 am

Edited : I’m not a early 170 guy but looking at the IPC figure 20 (which might be wrong in depicting the build up). I think the bushing should be aluminium to retain the tailwheel springs. Maybe the 2 rubber pads should have one on the top of the spring pack and one below the pack but that’s just another educated WAG. You’ll have to build it up and see what works. Use moulding clay when you build it up careful pull apart to measure the clay (voids)to be filled with rubber. That’s what I would do. Very not uncommon to see tailwheel hardware (attachment bolts) bent and under duress in neglected gear. Look at the vertical bolt holes, hopefully they are still round and the vertical attachment points have not been crushed.
I edited this post after looking at all three IPC’s 170, 170A, and early 170B. There’s small differences between models so there’s clues as to how it might be assembled. I’d try playing around and see what works best.
Last edited by c170b53 on Wed Feb 26, 2020 3:50 am, edited 1 time in total.
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Re: 1948 170 Tailwheel Bushing Replacement

Postby dstates » Wed Feb 26, 2020 3:31 am

My best guess would be for a metal bushing as well. The 170 and 170A tailwheel assemblies are very similar. The 170A parts catalog does not have the comment about rubber for the bushing. I’m guessing that it was a typo in the 170 catalog. If your part is aluminum (is it metallic and non-magnetic?) then I would install an aluminum bushing. I replaced the one on my 170A with a steel bushing. I still have my old one and can confirm if it is aluminum or steel tomorrow evening.

It is my opinion that if the bushing was rubber it would deteriorate in no time.

As far as the rubber pads go... one does go above and one below the spring stack. That is how my old ones were and how the 170B parts catalog shows it. Those pads are not available from any place I could find, so I used owner produced.

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Re: 1948 170 Tailwheel Bushing Replacement

Postby ghostflyer » Wed Feb 26, 2020 7:37 am

It was about 10 years ago I found my rubber bushing totally shot. It needs replacing . I looked everywhere and then in desperation I used some old rubber from engine baffles. That was 10 years ago .still all good.
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Re: 1948 170 Tailwheel Bushing Replacement

Postby Bruce Fenstermacher » Wed Feb 26, 2020 10:53 am

A problem here is Chris did not mention he has a '48 though a search of his N# confirms it. He also didn't say whether he has the original steel bracket or his has been changed out to the later fish mouth style. Most of us are more familiar with the later style. There are not many common parts between them. A picture would be worth a thousand words here.

So I'm thinking Chris's '48 still has the original steel mount. Looking at the IPC, if he is talking about item 80 and 81, they are rubber as confirmed by the IPC.
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Re: 1948 170 Tailwheel Bushing Replacement

Postby dstates » Wed Feb 26, 2020 12:50 pm

He did say he has a 48 170 in his subject line.

I still feel the rubber description there is likely a typo. If he took a metal one out, I would put a metal one back in. That is what the 170A has. You might argue that the 170A has a different part number, and it does, but it also only has 4 springs so it would have a different length of bushing.

That bushing is there to keep the springs aligned and takes a shear load as the springs "spread" when the tailwheel takes a vertical load. As a mechanical engineer for 20 years, I would never put a rubber bushing in a shear joint, period. It just wouldn't last very long. There are rubber pads above and below the springs taking a compression load to dampen the impact to the frame.

Can anyone else with experience disassembling a 170 tailwheel spring confirm if they had a metal or rubber bushing?

Doug

P.S. I just confirmed that my old bushing was steel from my 170A.
Last edited by dstates on Thu Feb 27, 2020 4:10 am, edited 1 time in total.
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Re: 1948 170 Tailwheel Bushing Replacement

Postby dstates » Wed Feb 26, 2020 12:58 pm

ghostflyer wrote:It was about 10 years ago I found my rubber bushing totally shot. It needs replacing . I looked everywhere and then in desperation I used some old rubber from engine baffles. That was 10 years ago .still all good.


Ghostflyer,

Are you saying you made a bushing or new rubber pads out of engine baffle material?
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Re: 1948 170 Tailwheel Bushing Replacement

Postby c170b53 » Wed Feb 26, 2020 1:28 pm

I think many underestimate the amount of load the tailwheel is subjected to. Bruce’s infamous helicopter like touch down video and maybe the professional pilot like types such as George Horn and the like are probably the exceptions to pounding their tail gear. I’m the opposite, no two landings are the same sequentially, I’m often a pound it down especially in a cross wind. It’s such thoughts that make me think the 48 IPC has the error on the bushing.
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Re: 1948 170 Tailwheel Bushing Replacement

Postby chrishartis » Wed Mar 04, 2020 3:24 pm

Thank you so much for your replies. After talking with other pilots on the field with 170’s I saw everything from “well I don’t have a piece there at all”, to rubber pieces, to aluminum pieces. I decided to leave on our rubber piece as it seems to do the job well even though it’s still a little bit hard. It’s always amazing to see how much this airplane has changed with its owners. Almost like a time machine of sorts. Thank you again for all your input!
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Re: 1948 170 Tailwheel Bushing Replacement

Postby gahorn » Wed Mar 04, 2020 4:27 pm

c170b53 wrote:I think many underestimate the amount of load the tailwheel is subjected to. Bruce’s infamous helicopter like touch down video and maybe the professional pilot like types such as George Horn and the like are probably the exceptions to pounding their tail gear. I’m the opposite, no two landings are the same sequentially, I’m often a pound it down especially in a cross wind. It’s such thoughts that make me think the 48 IPC has the error on the bushing.



I never professed to be a professional 170 pilot. (And I’ve never been paid for my opinions....or I’d owe someone money.). :mrgreen:

The Petit Jean video of Bruce’s spot/short landing speaks well of his professionalism however! :P
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Re: 1948 170 Tailwheel Bushing Replacement

Postby c170b53 » Wed Mar 04, 2020 7:29 pm

That’s the vid I refer to as a helo landing.
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Re: 1948 170 Tailwheel Bushing Replacement

Postby gahorn » Wed Mar 04, 2020 9:28 pm

Here’s a look at Bruce pretending he’s got a 40 kt headwind: https://www.youtube.com/watch?v=YsAk2zUNKOs
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Re: 1948 170 Tailwheel Bushing Replacement

Postby 170C » Wed Mar 04, 2020 11:08 pm

Had to have had something to do with those lightening bugs!
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Re: 1948 170 Tailwheel Bushing Replacement

Postby c170b53 » Thu Mar 05, 2020 12:21 am

Seen jug head at Oshkosh, he’s pretty good too!
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