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Posted

I recently read the article on nosewheel alignment '8 second ride'.

My M20E has a bit of shimmy in it that I want to get rid of, so I wondered if that would explain it. However, being outside and on grass, I wasn't going to jack it up to the correct level for the plumb bob, so I modenised it.

I used a digital level on the body, found out it was about 10 degrees from level, used the same level on the nose and adjusted about 10 degrees and voila, I have my answer. I think.

Where is the best place to get rubber doughnuts? 

P.s. i know its an American plane, but I can't bring myself to use the 'normal' spelling

P.p.s. the level was bought because its accurate enough to set a ground adjust prop

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  • Like 1
Posted
1 hour ago, RLCarter said:

If the top picture is where you got your 1st measurement from, it’s the wrong place, LASAR is where I I got my doughnuts from

Whoops, try again next time. 

"The seam above the access door to the tail cone" I assumed by that they mean the battery door? And the seam being where the sheets join on top.

So where is it?

I'll probably need doughnuts in any case, and hopefully that stops the shimmy. 

 

Posted
1 hour ago, Joshua Blackh4t said:

Whoops, try again next time. 

"The seam above the access door to the tail cone" I assumed by that they mean the battery door? And the seam being where the sheets join on top.

So where is it?

I'll probably need doughnuts in any case, and hopefully that stops the shimmy. 

 

Yes, that's right. But I thought it was the bottom seam there, where you can set the level down. It's on the side of the fuselage, where your photo looks to be sitting on the horizontal stabilizer. When I replaced my pucks, my IA bought them. Brand name of Lord, I believe.

Posted

You’re going to drive yourself crazy if you start placing a level on the ground and on the wings to determine whether the discs are worn- the service manual (or is it an Service Bulletin /Instruction/Letter?) has the procedure for taking a measurement - taken the top of the main gear strut when the plane is loaded with fuel and sitting on its wheels. You measure how high the strut collar sits above the area where it normally seats. Mooney gives a maximum dimension- someone here will know what it is for an M20C. I’m not near any manuals right now… The nose gear is not allowed to have any gap between the strut collar and the gear, I believe… This needs to be confirmed by reviewing the Mooney materials, though.

For shimmy, I’d be looking at tire condition (scalloped?), wheel balance, wheel bearing nut torque… if those are fine, then start looking at the gear. Nobody seems to balance wheels these days. When you do, you are horrified at how much weight it takes to get them balanced!

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Posted

Setting the gear up properly will certainly help… As 47U has shown above…

Then finding how worn out the nose gear steering bits and pieces are is the next step…

To get an OH’d nose gear part go to the Lasar website… Dan is THE parts guy there…

 

When do you get the shimmy?

On a properly set up nose gear, that isn’t worn out… you probably won’t get shimmy until past Vr and still on the ground…. :)

Best regards,

-a-
 

 

Posted
On 2/15/2022 at 3:05 AM, Joshua Blackh4t said:

Where is the best place to get rubber doughnuts? 

In the U. S. I think Aviall (now owned by Boeing) has the best price but they have never given me an account. 

Next best price is Aircraft Spruce. They have gone up considerably in price  in the past few months. I paid around $110 in November. Now they list for $139.95.

https://www.aircraftspruce.com/catalog/lgpages/lord-m20-mooney.php

Posted
5 hours ago, LANCECASPER said:

In the U. S. I think Aviall (now owned by Boeing) has the best price but they have never given me an account. 

Next best price is Aircraft Spruce. They have gone up considerably in price  in the past few months. I paid around $110 in November. Now they list for $139.95.

https://www.aircraftspruce.com/catalog/lgpages/lord-m20-mooney.php

Negative.  Herber aircraft is the best I’ve found.  Paid ~$100 last august. 11 discs plus shipping was less than $1150. Found them on controller. Said call for pricing. Could not believe the pricing.

Posted
On 2/15/2022 at 9:15 AM, PilotCoyote said:

You’re going to drive yourself crazy if you start placing a level on the ground and on the wings to determine whether the discs are worn- the service manual (or is it an Service Bulletin /Instruction/Letter?) has the procedure for taking a measurement - taken the top of the main gear strut when the plane is loaded with fuel and sitting on its wheels. You measure how high the strut collar sits above the area where it normally seats. Mooney gives a maximum dimension- someone here will know what it is for an M20C. I’m not near any manuals right now… The nose gear is not allowed to have any gap between the strut collar and the gear, I believe… This needs to be confirmed by reviewing the Mooney materials, though.

For shimmy, I’d be looking at tire condition (scalloped?), wheel balance, wheel bearing nut torque… if those are fine, then start looking at the gear. Nobody seems to balance wheels these days. When you do, you are horrified at how much weight it takes to get them balanced!

The correct answer

Posted

Lift the weight off the nose with a hoist and shake the nose gear back and forth, side to side and look for wear.  My nose had a shimmy that I could feel in the rudder pedals but I could not feel anything in the seat of my pants, but I'm sure it was only a matter of time.  If yours has a lot of play like mine did then consider sending yours nose truss to LASAR and let them rebuild it with new doughnuts and I think they also added steering limit stops too.  I also bought their rebuilt/upgraded steering horn. This way I did not have the headache of buying/renting any special tools and I am confident the work was done expertly by LASAR with documentation.  It fixed my shimmy 100% and I also consider it preventive maintenance. This repair/upgrade will last the remainder of the life of the aircraft if maintained properly.

Posted
5 hours ago, Bartman said:

Lift the weight off the nose with a hoist and shake the nose gear back and forth, side to side and look for wear.  My nose had a shimmy that I could feel in the rudder pedals but I could not feel anything in the seat of my pants, but I'm sure it was only a matter of time.  If yours has a lot of play like mine did then consider sending yours nose truss to LASAR and let them rebuild it with new doughnuts and I think they also added steering limit stops too.  I also bought their rebuilt/upgraded steering horn. This way I did not have the headache of buying/renting any special tools and I am confident the work was done expertly by LASAR with documentation.  It fixed my shimmy 100% and I also consider it preventive maintenance. This repair/upgrade will last the remainder of the life of the aircraft if maintained properly.

That would be great, but I can't wait the time it takes to send to USA and back. 

I'm hoping to get away with incremental upgrades, hopefully a tyre and doughnuts will keep her going smoothly for a while.

Maybe in the future it will get a full rebuild. 

I refuse to make a "project plane" out of her and want her to be a flying plane instead. 

 

Posted
18 hours ago, Joshua Blackh4t said:

Ok, take 2, still looks like it needs new doughnuts.

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You ae not measuring the  wear for the doughnuts correctly.

There is a collar at the top of each main gear (top center) that keeps the gear together, It is the gap between that collar and the plate below that is the place to check for the "wear" on the doughnuts (with weight on the landing gear).   There is a gap dimension allowed before condemning the doughnuts although many years of use makes them harder rubber than when  they wee new. 

Same holds true for the nose gear. You have to measure the gap in the correct place.   "Tail droop" doesn't mean bad doughnuts. 

If you can raise the nose wheel off the ground correctly and try to move it each way like steering If it has more than a few degrees of loose play its time for a linkage rebuild. Your mechanic can actually order all the parts that wear out in that linkage and reassemble it himself. Might be cheaper. There are some extra shims that hen might want to order. 

Posted

@Joshua Blackh4t Your best bet is download the correct service manual and any Service Letter or Bulletins that apply to the work being done…..Don’t cut corners on the instructions and expect the same results FOLLOW THE INSTRUCTIONS as outlined in the Mooney publications, if you’re not clear on something ask before guessing…. Not trying to slam you or your ability….

Posted
1 minute ago, RLCarter said:

@Joshua Blackh4t Your best bet is download the correct service manual and any Service Letter or Bulletins that apply to the work being done…..Don’t cut corners on the instructions and expect the same results FOLLOW THE INSTRUCTIONS as outlined in the Mooney publications, if you’re not clear on something ask before guessing…. Not trying to slam you or your ability….

Agreed, this was more of an exercise for fun. My mechanic will do anything serious.

I just wondered if I can replicate a rigging check and what it would tell me.

Most likely it needs a full rebuild, hopefully I can get a pass on the annual and we do it when parts arrive. 

I just liked the 8 second article and wanted to compare it. 

The rubbers will be old so good to replace anyway. 

Thanks for everyone's input

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