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Double groove trim on PA-12 -front pulley location

F

Frogdad

FRIEND
Midlothian, Tx
We located the front idler pulley on the diagonal fuselage tube just like on a PA-18. At that location it is not in line with the front drive pulley. It looks like the PA-12 tube angles inward where the PA-18 tube is straight up and down.
There is room to move the idler pully outward to align. Maybe some type of bracket.
What is the best way to do this?
 

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I had that same problem with my 12 and had to move it outboard as much as I could but it still didn`t line up perfectly but it isn`t as bad as yours looks
 
Keep in mind that the idler pulley must be angled with respect to the crank pulley to avoid having the endless cable rub on itself.
Potential Cable Rubbing.jpg
 

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I moved the pulley out until the cables rubbed then backed off a little. It only needed to move out about 1/4" or 3/8". looks like the cage can still weld direct to the fuselage tube without a bracket.
Thanks for the help.
 

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Notice that the cable is rubbing on the side of the groove on the inboard pulley. This could cause excessive wear on both the pulley and cable. Try moving the idler pulley some more. The idler axle does not want to be parallel to the crank axle. Not sure that I said this right. Look very closely at Darrel's picture.
 
Frogdad, looks like you installed Oilite bearing at the crank - that too is an important change. Good job.
 
this is a job for a pulley positioning tool!!

I forgot about that...

just bend up some 1/16" welding rod around the pulleys

 
Mine has a bronze bushing on one side where can I get the oilite bushings for both sides? thanks
 
Mine had worn a groove in the clevis in so the bushings will help me. I was going to turn one on the lathe but I can buy one easier
 
Guess things in Anchorage are a world apart because the steel pulley brackets running against a steel shaft wear out fast in Minnesota. You are lucky to live in a non-wearout state.
 
Darrel Starr said:
Guess things in Anchorage are a world apart because the steel pulley brackets running against a steel shaft wear out fast in Minnesota. You are lucky to live in a non-wearout state.
Click to expand...

not gonna get in a pissing match with an over-engineer on a 1930's design....

so you magically fix that end of the steel on steel problem, and did ya fix the other end??

I go by what wears out by inspection on disassembly, to judge what needs attention.. and THAT DOES NOT warrant consideration anymore

I'm done......
 
I'm not sure what I can add to this conversation but I will second the oilite bushing. I installed new clevis pin and new stand off brackets for the main crank pulley. Mine were COMPLETELY wallowed out, in a real bad way. I initially installed the new clevis pin with lube on it. It was soo hard to turn with it being steel on steel. I took it all apart and installed the oilite bushing as in Darrel's diagram. My crank mechanism is now like butter. I think it's a must for all cubs. I haven't flown the plane yet but I do not anticipate and problems once airborne.
 
Thanks Kevin, Your experience mirrors mine and several other SCs here at KANE. Two owners had a round inspection ring installed in the fabric next to the crank pulley so they could CAREFULLY move the pulley keeping the endless cable from slipping out of sight so they could then make the modification. Worked well in both cases. These were "new" SCs built up with new Airframes Inc. fuselages (when Lee Bode was still making them) but the brackets started to wear within the first 100 hrs making the crank hard to turn.
 
mike mcs repair said:
they don't...
and you ALWAYS replace the pin/shaft at rebuild, just like all the rest of the CAD plated hardware that doesn't get reused.
Click to expand...
Dang, so only the shaft wears!? Suuuure. So how come I had plenty of bores to re-machine and re-fit in my machine shop? Oh, musta been all that Minnesota machinery that showed up in Alaska at that time. C'mon, Mike - you aren't the only experienced person around - - -
 
Darrel Starr said:
Thanks Kevin, Your experience mirrors mine and several other SCs here at KANE. Two owners had a round inspection ring installed in the fabric next to the crank pulley so they could CAREFULLY move the pulley keeping the endless cable from slipping out of sight so they could then make the modification. Worked well in both cases. These were "new" SCs built up with new Airframes Inc. fuselages (when Lee Bode was still making them) but the brackets started to wear within the first 100 hrs making the crank hard to turn.
Click to expand...
The early Airframes fuselage I have seen wore prematurely. Have seen the same thing on Piper fuselage but took way, way more hours. I fix at rebuild and should last till the next one.
 
Steve, sounds right. My original Piper fuselage had wallowed out brackets too but with about 3600 hrs. - assuming the brackets were original.
 
1979 model Super Cub with 2800 hours total time. Wore slap ass out.
trim.jpg
Parts cut out.
trim2.jpg
New parts but solid stock instead of folded over like original.
trim3.jpg
Welded in.
trim4.jpg
 

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kevin said:
I'm not sure what I can add to this conversation but I will second the oilite bushing. I installed new clevis pin and new stand off brackets for the main crank pulley. Mine were COMPLETELY wallowed out, in a real bad way. I initially installed the new clevis pin with lube on it. It was soo hard to turn with it being steel on steel. I took it all apart and installed the oilite bushing as in Darrel's diagram. My crank mechanism is now like butter. I think it's a must for all cubs. I haven't flown the plane yet but I do not anticipate and problems once airborne.
Click to expand...

I’ve done the oilite bearings mod and I assure you that the trim action in flight is a DELIGHT which is pretty important with the pretty much constant retrimming the PA-12 needs. You WILL NOT be sorry you went the extra yard to install them :)


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Darrel Starr said:
Thanks Kevin, Your experience mirrors mine and several other SCs here at KANE. Two owners had a round inspection ring installed in the fabric next to the crank pulley so they could CAREFULLY move the pulley keeping the endless cable from slipping out of sight so they could then make the modification. Worked well in both cases. These were "new" SCs built up with new Airframes Inc. fuselages (when Lee Bode was still making them) but the brackets started to wear within the first 100 hrs making the crank hard to turn.
Click to expand...

I did exactly this too and cut and fitted an external access panel and makes the whole job MUCH easier.

Before I removed the winding shaft, I put a loop of electrical wire through the trim cable loop and tied it to the throttle lever to ensure that the trim cable couldn’t fall back into the fuselage. It also helped when fitting the trim cable onto the new trim pulley as it could be easily pulled and tensioned

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Sent from my iPhone using SuperCub.Org mobile app
 

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Last edited:
Aircraft spruce is out to the end of February for the an396-59 clevis pin. Seeing how I’m deep into this retrofit and it’s holding up other parts of our project I’d be very grateful and would pay a premium to anyone who could send me one ASAP.


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