M20 Ogler Posted June 26, 2021 Report Posted June 26, 2021 The donuts in my mains were replaced a few months ago. I noticed the left wing tip has about 2 1/2” more ground clearance than the right. Tire pressure are equal so I measured the donut stacks. The right is compressed about 1/8” more than the left. Is there anything that can be done about this? Maybe split the difference between them? Quote
carusoam Posted June 27, 2021 Report Posted June 27, 2021 9 hours ago, M20 Ogler said: The donuts in my mains were replaced a few months ago. I noticed the left wing tip has about 2 1/2” more ground clearance than the right. Tire pressure are equal so I measured the donut stacks. The right is compressed about 1/8” more than the left. Is there anything that can be done about this? Maybe split the difference between them? Check with your mechanic to see what’s up with that… Do a visual check to see what isn’t right. That just doesn’t sound right… for identical donuts… Something got left out of one of the stacks… PP thoughts only, -a- 1 Quote
M20 Ogler Posted June 27, 2021 Author Report Posted June 27, 2021 I was thinking maybe they just compressed one side more than the other. But yeah you may be right about the stack not being correct, I did not think of that. I’ll have to look at it closely. Also PP thoughts only. 1 Quote
RobertGary1 Posted June 27, 2021 Report Posted June 27, 2021 2 hours ago, M20 Ogler said: I was thinking maybe they just compressed one side more than the other. But yeah you may be right about the stack not being correct, I did not think of that. I’ll have to look at it closely. Also PP thoughts only. The mains are only compressed by the weight of the aircraft. Do you have similar fuel in both tanks? 1 Quote
Guest Posted June 27, 2021 Report Posted June 27, 2021 Compare the collar on the top of the gear leg. The hole in the collar should be centered in the height of the collar, also look for a washer under the collar, these are normally used to adjust the nose. Clarence Quote
Shadrach Posted June 27, 2021 Report Posted June 27, 2021 (edited) There is a collar bolt on each side that must be aligned with an access hole in order to disassemble the gear. It will not be aligned with the airplane off jacks but the bolt should be in the same place relative to the hole on both gear. Edited June 27, 2021 by Shadrach 1 Quote
M20 Ogler Posted June 27, 2021 Author Report Posted June 27, 2021 (edited) My previous plane was a Beechcraft Sundowner, it’s donuts get heated to 120 degrees for 24 hours then compressed in a press fixture prior to the gear leg being reinstalled on the airplane. I assume Mooney’s would be a similar ordeal. Is it like that for a Mooney? Edited June 27, 2021 by M20 Ogler Quote
Hank Posted June 27, 2021 Report Posted June 27, 2021 6 minutes ago, M20 Ogler said: My previous plane was a Beechcraft Sundowner, it’s donuts get heated to 120 degrees for 24 hours then compressed in a press fixture prior to the gear leg being reinstalled on the airplane. I assume Mooney’s would be a similar ordeal. Is it like that for a Mooney? No. Remove the donuts from the box, stack them up, and assemble onto the post. Weight of the plane compresses them when everything is back together and the wheels are back in the ground. There's no need to pre-compress them. 1 Quote
Shadrach Posted June 27, 2021 Report Posted June 27, 2021 48 minutes ago, M20 Ogler said: My previous plane was a Beechcraft Sundowner, it’s donuts get heated to 120 degrees for 24 hours then compressed in a press fixture prior to the gear leg being reinstalled on the airplane. I assume Mooney’s would be a similar ordeal. Is it like that for a Mooney? That reads like a needlessly complicated procedure. If the donuts are manufactured with a reasonable degree of precision with regard to dimensions and material characteristic there should be no need to preform them. I’m trying to imagine what heating and compressing actually does for them. Quote
Shadrach Posted June 27, 2021 Report Posted June 27, 2021 18 minutes ago, M20Doc said: This may help as well. Each of the collars on my bird are machined on one side. The illustration does not show that. Can you verify how it should be oriented. Neither the IPC nor MM make mention of it. We know how it was oriented when removed but it would be nice to get verification. Quote
67 m20F chump Posted June 27, 2021 Report Posted June 27, 2021 I thought you could only push the bolt in one way? Quote
Guest Posted June 27, 2021 Report Posted June 27, 2021 6 hours ago, Shadrach said: Each of the collars on my bird are machined on one side. The illustration does not show that. Can you verify how it should be oriented. Neither the IPC nor MM make mention of it. We know how it was oriented when removed but it would be nice to get verification. Flat side forward of there is a clearance issue. Quote
Shadrach Posted June 27, 2021 Report Posted June 27, 2021 Just now, M20Doc said: Flat side forward of there is a clearance issue. Thanks Clarence. Ours were mounted forward with the machined side down. I assumed in any other orientation it miht interfere with the steel gusset when the gear compresses. Quote
M20 Ogler Posted June 28, 2021 Author Report Posted June 28, 2021 14 hours ago, Shadrach said: That reads like a needlessly complicated procedure. If the donuts are manufactured with a reasonable degree of precision with regard to dimensions and material characteristic there should be no need to preform them. I’m trying to imagine what heating and compressing actually does for them. I’m guessing it’s needed because Sundowners, Sierras, Musketeers and all the other “Mouses” have trailing link landing gear so the donuts have to withstand more leverage. Therefore you have to preload the donuts enough to take the force of a hard landing. Heating them softens them enough to prevent them from splitting when compressing them. And you don’t want to split them they cost about $1400 per stack. Quote
Shadrach Posted June 28, 2021 Report Posted June 28, 2021 (edited) On 6/28/2021 at 1:18 AM, M20 Ogler said: I’m guessing it’s needed because Sundowners, Sierras, Musketeers and all the other “Mouses” have trailing link landing gear so the donuts have to withstand more leverage. Therefore you have to preload the donuts enough to take the force of a hard landing. Heating them softens them enough to prevent them from splitting when compressing them. And you don’t want to split them they cost about $1400 per stack. Take a closer look at the gear on your M20. It is also a trailing link design and with similar geometry. The most obvious difference being that the Beech uses thinner discs but twice as many. Edited June 29, 2021 by Shadrach 1 Quote
carusoam Posted June 30, 2021 Report Posted June 30, 2021 I like the idea of heating rubber prior to compressing them…. But… We compress them a lot when the plane is fully loaded and we stall a foot above the runway… I don’t remember heating them during winter ops in NJ. -a- Quote
RobertGary1 Posted June 30, 2021 Report Posted June 30, 2021 5 minutes ago, carusoam said: I like the idea of heating rubber prior to compressing them…. But… We compress them a lot when the plane is fully loaded and we stall a foot above the runway… I don’t remember heating them during winter ops in NJ. -a- I think the main item of interest for Mooney owners is that the mains are not compressed when the plane is airborne. Maybe it would make sense for the nose that is??? Would it reduce the need for the compression tool? Quote
Guest Posted June 30, 2021 Report Posted June 30, 2021 3 hours ago, RobertGary1 said: I think the main item of interest for Mooney owners is that the mains are not compressed when the plane is airborne. Maybe it would make sense for the nose that is??? Would it reduce the need for the compression tool? The discs remain under quite a bit of compression while in flight or while on jacks. If there was no compression we wouldn’t need the compression tools to install them. Clarence Quote
RobertGary1 Posted June 30, 2021 Report Posted June 30, 2021 5 hours ago, M20Doc said: The discs remain under quite a bit of compression while in flight or while on jacks. If there was no compression we wouldn’t need the compression tools to install them. Clarence The nose does but the mains seem to hang. I can grab the main donuts and spin them around by hand when on jacks. Quote
Guest Posted June 30, 2021 Report Posted June 30, 2021 6 hours ago, RobertGary1 said: The nose does but the mains seem to hang. I can grab the main donuts and spin them around by hand when on jacks. Then they’re likely compressed beyond limits. Clarence Quote
RobertGary1 Posted June 30, 2021 Report Posted June 30, 2021 (edited) 5 minutes ago, M20Doc said: Then they’re likely compressed beyond limits. Clarence But 0.6” is a lot. I’m at 0.3”. That’s still pretty free when not under load. -Robert Edited June 30, 2021 by RobertGary1 Quote
Guest Posted June 30, 2021 Report Posted June 30, 2021 My experience has been that under no load on jacks or in flight, there should be no free play in the shock disc stack. Clarence Quote
M20 Ogler Posted July 4, 2021 Author Report Posted July 4, 2021 (edited) The collar bolt is centered in the access hole on the left main but it is not centered on the right main. I’m having difficulty seeing if there is also a washer in there. Edited July 4, 2021 by M20 Ogler Quote
Guest Posted July 4, 2021 Report Posted July 4, 2021 14 minutes ago, M20 Ogler said: The collar bolt is centered in the access hole on the left main but it is not centered on the right main. I’m having difficulty seeing if there is also a washer in there. You can like the small metal cover off to expose the top collar and the bolt and nut. Some top collars have an offset hole allowing more or less compression, these are normally installed on the nose. The mains should be the same height. Clarence Quote
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