1966 M20E Manual Gear Tension Question

[Cessna738]

Checking the tension on the landing gear. I know the required specs. But, I have read that the proper way to confirm the inch-pound release is with a shim. When it slips out, check the torque number. But, where is the shim placed?

[N201MKTurbo]

24 minutes ago, Cessna738 said:

Checking the tension on the landing gear. I know the required specs. But, I have read that the proper way to confirm the inch-pound release is with a shim. When it slips out, check the torque number. But, where is the shim placed?

Place the shim in the over center link. I just use a piece of paper. Use the tools to open the over center link, slide the paper in, then relax the tool which will trap the paper. Gently pull on the paper while looking at the torque wrench. Note the reading when the paper slips out.

A torque wrench with a dial or a bending beam type is a lot easier to use for this then a click wrench.

[EricJ]

+1 on a piece of paper, which is essentially the same thickness as the specified shim.    The first time I did it I used one my nice measuring shims and it ruined it, so I always use a piece of paper now.    Derp.

The Service Maintenance Manual for most Mooneys has a drawing of the gear and where the shim goes and how to use the tool to check the preload.   If you have a click-type torque wrench set it for the minimum spec and the wrench should click without the peice of paper coming out.   Then set it for the max spec and the paper should come out before the wrench clicks.   If that happens the system is within spec.

[RLCarter]

dial type with memory pointer is the best, slowly increasing pressure till the paper slips out, take several readings until you get the “Feel” . Trap the shim (paper) the same amount or your results will be different each time 

[carusoam]

Great pics RLC!

best regards,

-a-

[cliffy]

Just cut a slim shim from a soda can with scissors and us it. 

Make it as long as you need. Cheap, available, throw it away when you're done. 

Forgot to add-  I do better just by feel but I've done it for 3 or 4 decades

Edited January 1, 2023 by cliffy
add

[goalstop]

How much does the gear tension preload impact ease of retraction / extension? My mechanic said mine is 1-2# heavy and would be 2.5 hours to adjust. Will there be any discernible difference from this change? For context - getting it set up for the wife to fly, and she’s found the bar pretty heavy / cumbersome to swing

with all the levers and pulleys involved, what does 1-2# of preload translate to in the handle?

[takair]

1 hour ago, goalstop said:

How much does the gear tension preload impact ease of retraction / extension? My mechanic said mine is 1-2# heavy and would be 2.5 hours to adjust. Will there be any discernible difference from this change? For context - getting it set up for the wife to fly, and she’s found the bar pretty heavy / cumbersome to swing

with all the levers and pulleys involved, what does 1-2# of preload translate to in the handle?

I’m surprised he can measure 1-2 lb.  I usually do mine 4 or 5 times to get an average.  I don’t think 1-2 will make much difference, 5 to 10 might.  If having trouble getting it to latch in the down position because it is over the max spec, then it is worth reducing it to the mid point.  I tend to try to keep mine at the lower end of the spec.  2.5 hours seems reasonable.  You have to Jack the plane, remove panels, adjust the loads, readjust the nose gear recheck all, maybe adjust them all some more, inspect, reinstall panels, remove from jacks and do paperwork.  
 

Edit….I think he is saying it is just over the max limit.  He would likely take a half turn which would be a good number to put it closer to the middle…maybe a full turn.  In other words, not real way to adjust 1 or 2 pounds anyway, since you have to go in half turn increments.  I never really paid attention to how much that’s worth, but guessing about 5 lb.

[cliffy]

1 to 2#s heavy where? One main gear? Nose gear?  Any time you change ONE setting you have to go back and check ALL settings

because one affects all. Its can become a circle the drain exercise. .

Really hard to see 1 or 2#s torque. Won't make that much difference in feel. 

Make sure every joint and connection that moves is well lubricated. Dry connections make the gear hard to move. 

What airspeed is she trying to retract the gear? High speed (+85 mph) makes for a hard retract. 

[47U]

3 hours ago, goalstop said:

- getting it set up for the wife to fly, and she’s found the bar pretty heavy / cumbersome to swing

You might put a straight edge on the bar and make sure it’s not bent.  I think @Sabremech discovered that in his C (before it became Hammdo’s C), once upon a time.

A theory… when the gear is down, the main gear rods are in compression and the nose gear rods are in tension, right?  So, wouldn’t screwing the main gear rods in a half-turn, and screwing the nose gear rods out a half-turn result in no change in the torque values, but serve to move the top of the johnson bar towards the down lock in the panel by a skosh?  Wouldn’t that reduce the amount of force required to lock the bar into the block?  

Obviously, like Cliffy says, after ANY adjustments, ALL readings need to be rechecked.