change axle...

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BoKu

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Well, hacksaw, plasma cutter, and oxy cutting torch come to mind. If it's like similar Aeroncas, the axle is an extension of the lower inboard tube that has been machine tapered and then turned to a precision fit with the bearing inner races. But that rises the bigger question, how would you propose to attach the 4-bolt axle? That brake mounting flange is probably not up to the job. You'd have to design and execute an attachment that is capable of reacting the necessary moments out of the axle and into the weldment.
 

Twodeaddogs

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thanks for the answer. the new stub axles are four bolt type which match the existing holes on the flange. What you have said confirms what appears to be: a fixed,tapered axle.
 

wsimpso1

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I'd like to change the axles on this Spezio main gear for a newer Cessna type 4-bolts tub axle. Is there any option for getting the existing stub off, without taking a grinder to it?
Why? Is there something wrong with that axle?

The four bolt axles are for bolting on a beefy gear end, like with a Wittman type spring gear or other arrangement. The holes line up because the same bolts are also used to anchor the brake caliper. That little flange on your gear is designed to carry brake reaction loads not wheel reaction loads... You would have to machine and weld on a beefier flange.

If you are changing the wheel type, well, let's get into the whys and whats. Mostly, why do you need a different axle?

Billski
 

Twodeaddogs

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The aircraft came with the old type of wheel and brake unit,which uses clips to hold in a floating brake disc. They are obsolete and they are a pig to deal with and the Cessna type is so much easier to deal with when it comes to changing pads or swapping tyres. I can certainly beef up the flange.
 

Dan Thomas

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Yes, get rid of those Goodyears. Horrible things. They were famous for locking up the wheel if the brake pad wore thin enough to slip out of its cavity and wedge itself between the caliper and disc.

But you will need to really beef up that gear to carry an axle. On rod-type gear legs, the rod goes into that hollow axle and its flange only carries the brake caliper. The 182 RG uses rod gear with a beefy casting on its end to carry the axle. On the older flat leaf gear, it bolts to the leaf, and often uses 5/16" bolts in the top holes and 3/8" in the bottom. The bottom bolts are loaded in tension and shear, the tops mostly in shear.

You might cut the axle off 3/8" or 1/2" out from the flange and machine a steel disc of that thickness with a hole that will fit very closely over the axle, and weld it to the axle and flange. Machining a 1/4" wide chamfer into the outside of the bore in that disc, and tapering the end of the stub a little, would allow a good, thick weld in the resulting vee.
 

wsimpso1

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The aircraft came with the old type of wheel and brake unit,which uses clips to hold in a floating brake disc. They are obsolete and they are a pig to deal with and the Cessna type is so much easier to deal with when it comes to changing pads or swapping tyres. I can certainly beef up the flange.
I would look hard at the amount of welding and machining etc to put a beefy flange on vs making a new steel tube axle to modern wheel/brake that is then fit in and welded. Another option is to evaluate how much you would have to do the existing axle to fit modern brakes and wheels on it. once you have figured out the options, you can figure out which one you will build and make reliable...

Billski
 

tailwind

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Just weld the right size axle chunks over it, clip wing taylorcrafts had a sketch to put a 1.25 stub for the outer bearing and axle nut on the shinn axles.
 

BoKu

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Just weld the right size axle chunks over it, clip wing taylorcrafts had a sketch to put a 1.25 stub for the outer bearing and axle nut on the shinn axles.
Or maybe just make a bushing for the outboard bearing.
 
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