Buying used rims and big price differences

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PoconoJohn
Posts: 165
Joined: Tue Jan 14, 2020 9:07 pm

Buying used rims and big price differences

Post by PoconoJohn »

I'm looking at two rims to buy and there's a $250 difference in price. The cheaper one looks much better and I can't figure out why that would be. What do you think? I'd love to buy new rims, but $2K is steep and I'm leaning to mechanical disc caliper go-kart brakes (not hydraulic).

https://aircraftpartsandsalvage.com/air ... -11/#40-97

https://www.smithsalvageandrestoration. ... ype_3.html

New ones: https://www.groveaircraft.com/61-1.html

Thanks,

John C
jeffreyK
Posts: 43
Joined: Wed Jan 15, 2020 9:41 pm

Re: Buying used rims and big price differences

Post by jeffreyK »

John,
I'm not a engineer or mechanic so take this with a grain of salt or two. I had purchased the builders 1-1/2 inch axles from ASS. I had a lot of trouble finding wheels and brakes that weren't expensive and overkill for the Kinetic Energy and Torque requirements for the plane. I spoke with a tech at Matco who stated that the axle I was using may have been common years ago but smaller axles are now used on the lighter planes. Based on the Piet's numbers he advised a 1-1/4" axle for which I bought 2 new 6.00 x6 wheels and external caliper brakes for $900. The axles were about $100 each.
I have built my gear legs but haven't put the axle mount on yet. That is looking to be a rather complex cut and weld. One advantage I see to my change is that if for any reason my axle mounts aren't perfectly in line, shims can be added between the mount and the axle to align them. I believe it was Oscar Z who I got the idea from. During the last few months, he has posted pictures in the forum of his gear and the process of aligning them. I apologize if it wasn't him but if you checkout the gear postings the last few months you'll find what I'm talking about. I took many pictures of the Piet's at Brodhead last year and quite a few people use this technique.
JeffreyK
PoconoJohn
Posts: 165
Joined: Tue Jan 14, 2020 9:07 pm

Re: Buying used rims and big price differences

Post by PoconoJohn »

I don't think I've seen rims that take a 1.25" axle. I'll have to look (for used ones). Meanwhile, the AS&S 1.5" axle's sit waiting.

Gear legs are done and the top end's are set to attach to the gear fittings (all fittings have to be trashed as I made them per full size template-another delay).

I've seen about the shims, but I don't understand how they work. I have to find a rim first.

John C
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taildrags
Posts: 637
Joined: Tue Mar 07, 2017 10:39 pm

Re: Buying used rims and big price differences

Post by taildrags »

1. Yes, I'm one who has used the tapered shims to get my Piet's wheels to track exactly where I want them to. Now, with the spring-strut "Cub style" gear that I'm using, the geometry changes and the gear is loaded, both static (just adding passenger and full fuel to the plane where it sits) and dynamically (plonking it onto the runway "enthusiastically"). But it's a method of fine-tuning without having to cut and re-weld, or heat and bend, or any of that.

2. As far as 1-1/4" axles, from what I've seen, there are plenty of Clevelands that take that size axle, both 5" and 6" wheels, but I haven't actively looked for any.

-Oscar
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