Gear Rigging

[RLCarter]

 Just spent the afternoon checking the rigging of my manual gear E. Both my A&P/IA and I read the Maintenance Manual, Service Bulletin and the Service Instruction multiple times each to get a full understanding of the task that was about to take place. Armed with the knowledge we set out to check the nose gear, first the IA ran the torque wrench while I detected any movement (this was done several times). Next we switched and he detected the movement several times as well. The IA consistently detected movement at 96 in-lb of torque while I came up with 90 in-lb. Being below the minimum of 100 in-lb an adjustment was made and rechecked by both, it now reads 102~106 in-lb, on the light side but with in range so it was off to the mains Right Main came in at 246 and 252 (pretty consistent, still 6 in-lbs between us). The Left Main came in a little higher at 264 and 270, but with in the 25 in-lb difference between them so no adjustment was made on the Mains. I’m happy that this now out of the way and that they are within the limits set by Mooney. Actual time was maybe an hour but the belly skin was already off and was not reinstalled afterwards and we only had to adjust the Nose Gear rods a half turn. What burned up the rest of the day was discussing what a crude method it was for setting what I would consider a crucial value. While we had readings within 6 in-lb of each other someone else might of come up with a much higher or lower reading depending on their sensitivity for detecting movement. Anyone that has checked/rigged their gear feel the same way?

[Bob_Belville]

Just now, RLCarter said:

 Just spent the afternoon checking the rigging of my manual gear E. Both my A&P/IA and I read the Maintenance Manual, Service Bulletin and the Service Instruction multiple times each to get a full understanding of the task that was about to take place. Armed with the knowledge we set out to check the nose gear, first the IA ran the torque wrench while I detected any movement (this was done several times). Next we switched and he detected the movement several times as well. The IA consistently detected movement at 96 in-lb of torque while I came up with 90 in-lb. Being below the minimum of 100 in-lb an adjustment was made and rechecked by both, it now reads 102~106 in-lb, on the light side but with in range so it was off to the mains Right Main came in at 246 and 252 (pretty consistent, still 6 in-lbs between us). The Left Main came in a little higher at 264 and 270, but with in the 25 in-lb difference between them so no adjustment was made on the Mains. I’m happy that this now out of the way and that they are within the limits set by Mooney. Actual time was maybe an hour but the belly skin was already off and was not reinstalled afterwards and we only had to adjust the Nose Gear rods a half turn. What burned up the rest of the day was discussing what a crude method it was for setting what I would consider a crucial value. While we had readings within 6 in-lb of each other someone else might of come up with a much higher or lower reading depending on their sensitivity for detecting movement. Anyone that has checked/rigged their gear feel the same way?

I would think you or your mechanic should talk to DMax. He's been doing this every day for almost 50 years.

[RLCarter]

We didn't have any issues performing the task, it actually straight forward and easily done. My issue is in the way it is done, I would bet you could have 6 well experienced Mooney guys all check the gear and you would come up with 6 different settings measured  

[N201MKTurbo]

I think that it isn't as critical as most people think. The early service manuals had you measure the rod spring compressions with a ruler. If you set the gear so all the springs are about half compressed, your torques will be correct. I think that they switched to the torque wrench method, because to many people were screwing up the spring compression method.

if you want to go through your whole system you can get the preloads very even. I have found that getting both nose gear rods to have the same amount of compression to get the correct torque is vital. You can have one of them causing all the preload and the other one doing nothing, you will get he correct nose gear preload, but your whole system will be cadywhumpus.

[RLCarter]

Nose gear tubes were set a half turn apart, got them even then set the preload. I have a service manual from 1966 (not current and not the one I use)..same procedure as today just higher torque values, Nose 140~200 ideally 170 with the Mains being 275~325 and should be equal

[1964-M20E]

yes it is straight forward not complicated time consuming though.  Yes you will get different readings each time you do it.  I have dial torque wrench I use with a memory needle to make it easier to get the values.

 

 

[RLCarter]

1964-M20E,
What torque wrench (make/model) are you using that spans the range needed, we ended up use 3 different wrenchs, could have gotten by with 2 but I wanted to know what the Nose was reading

[Andy95W]

20 minutes ago, RLCarter said:

Nose gear tubes were set a half turn apart, got them even then set the preload. I have a service manual from 1966 (not current and not the one I use)..same procedure as today just higher torque values, Nose 140~200 ideally 170 with the Mains being 275~325 and should be equal

Service Bulletin M20-155 (which became an AD) deals with the installation of improved retract links.  This SB made these old, higher values incorrect.

1 hour ago, RLCarter said:

We didn't have any issues performing the task, it actually straight forward and easily done. My issue is in the way it is done, I would bet you could have 6 well experienced Mooney guys all check the gear and you would come up with 6 different settings measured  

Yes, you would get 6 different measurements, and they would all be within the limits prescribed.  You and your mechanic were only 6 in-lbs different.  I would call that extremely close and exceptionally accurate.  6 in-lbs is NOT very much.

 It's a Mooney mechanical landing gear, not a Swiss watch.  It really doesn't have to be that close.

[RLCarter]

Just now, N1395W said:

It's a Mooney mechanical landing gear, not a Swiss watch.

Coming from many years in the motorcycle industry and working with tolerances as little as 0.01mm (0.0005") and 1000cc (61 cu in) engines that turn 14k rpm and crank out 200+hp I sometimes forget.....lol

[N201MKTurbo]

To get an accurate reading, slip a piece of paper in the overcenter link. pull on the paper and record the reading when the paper slips out.

[RLCarter]

8 hours ago, N201MKTurbo said:

To get an accurate reading, slip a piece of paper in the overcenter link. pull on the paper and record the reading when the paper slips out.

Good idea, if the numbers would have been all over the place, I was going to put a dial indicator on them

[ltdoyle]

What would be great is someone posting a you-tube video of the process!!!

[Guitarmaster]

I wish I would have thought of that during the annual. We rerigged the entire gear from Ground Zero. Not particularly hard, but a little time consuming.

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[RLCarter]

Getting video might be tough, with the tool and torque wrench an a hand to feel for movement there isn't much room. The actual process isn't that difficult at all, we spent maybe an hour but after N201 suggested the paper I went back and rechecked them in less than 20 minutes (was still on the jacks)

[RLCarter]

During the rigging we used my IA's torque wrenches and rigging tools, I ended up finding a 0-300 lb-in dial type torque wrench and while putting my new torque wrench up I noticed something that didn't look right about the main gear rigging tool. It didn't take long to see that on the tool I purchased from LASAR had the 1/2" square drive clocked at a 45* angle making impossible to install a torque wrench with a fixed drive perpendicular to the horizontal tube of the retraction truss. I placed a call to LASAR but everyone was tied up and that someone would give me a call back. Paul called me back with in an hour and confirmed that they rotate the 1/2" drive to 45* and it works fine and that will not change the torque readings and that I could buy a 3/8 to 1/2" adaptor that would bring the wrench back to 90*. I have never seen one and he couldn't tell me where to get one from. Anyone have any experience with this? I don't feel like doing the math to come up with the new values or make an adaptor or weld up the tool and machine it correctly.

[N201MKTurbo]

You don't have to machine of figure anything, just get a 3/8 to 1/2 adapter, it will rotate the torque wrench 45 deg. 

This assumes that you are using a 3/8 drive torque wrench, which you should.

[kortopates]

I believe its a 1/2" to 3/8" adapter i.e. the male end is 1/2" ( not a 3/8" to 1/2" which has a 3/8" male end). Its mandatory to fit the 3/8" torque wrench into the 1/2" size gear rigging tool. But I don't recall mine changing the clock position - but I could be wrong since I have never really thought about it. I have always been able to put the torque wrench on at the 3'oclock position to the gear rigging tool on the mains (which is the only one of the two tools I use on mine).

[RLCarter]

5 hours ago, N201MKTurbo said:

You don't have to machine of figure anything, just get a 3/8 to 1/2 adapter, it will rotate the torque wrench 45 deg. 

This assumes that you are using a 3/8 drive torque wrench, which you should.

What brand of adapter or where did you purchase yours? I have 1/4"~3/4" (in both directions) and all of them have the drives squared to each other.

[N201MKTurbo]

I,ll have to look next time I'm out at the hangar. I think mine are Craftsman. I know the torque wrench comes straight off of tool when I use it. 

[RLCarter]

Thanks, might stop by Sears on my way out this afternoon, looking on the net it looks like the 3/8" end of the Craftsman adapter is an 8 point allowing for the rotation needed.

[N201MKTurbo]

A quick web search shows they come both ways

[RLCarter]

Stopped by Sears and picked up the 3/8 x 1/2" adapter, out of the 6 I own 1/4 ~ 3/4 going both ways none of the a clocked at 45* and have never needed one to be, untill now. Thanks guys

[DaV8or]

Sorry to resurrect this old thread, but I'm going through this now.

First, I'd like to say that I am sadly disappointed in the "special tool" to check the preload. It's kinda crappy. Why in the world is it made for a 1/2" drive?? I own three torque wrenches in the suitable range of the manual's requirements and they are all 3/8" drive. I can't imagine a torque wrench that is 1/2" drive and measures inch/pounds. OK, so I tried an adapter that goes 3/8-1/2" and it sucked. It made the tool unusable. Not only was my wrench clocked 45 degrees off, so not at 90 degrees like the manual shows, but also the torque is now applied well off axis and this causes the tool to slip all over the place and fall off.

This brings up the second stupid thing about this tool. It has nothing to secure it at the pivot point. It can easily slip off if the torque isn't applied as close to axis of the gear rods as possible. I'm thinking of modifying mine by getting out the welder and making a little tang that goes up into the fork in the rigging push rod just above it to keep it from slipping too far. I realize that not all Mooneys may not be the same and this tool is made for all of them I guess, but on mine anyhow, a little something in that fork would really help.

I solved some problems by making a slip on 3/8-1/2" adapter from some 1/2" square tubing I had. This allowed my wrench to be 90 degrees and also as close as possible to on axis to prevent slipping. I still have to hold he tool with my free hand to prevent some slipping. As best I can tell, using a dial torque wrench with a memory needle, my mains are set at around 310 inch-pounds. They were last set by LASAR and are very close left to right. The manual calls for 240-280 inch-pounds. Should I mess with them, or is a little extra a good idea these days?? Should I trust my readings? The whole thing seems kind of imprecise and loose to interpretation. 

Hate that. 

[carusoam]

Dave,

I'm glad you asked.

Since there is a range, that implies there is a too much, and a too little.  Too important to not get a solid answer...

Good luck,

-a-

[Guitarmaster]

Give Brian at Wilmar a shout. That's who I talked to when I did mine.
Very knowledgeable and willing to help.

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