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  #1  
Old 02-15-2018, 10:54 PM
iamtheari iamtheari is offline
 
Join Date: Nov 2017
Location: ND
Posts: 155
Default Rudder rod end bearings

I finally got the back ordered parts from the empennage kit today. There was a note in the hardware bag #1902, which said that the MD36-14M rod end bearings were replaced with MM-3M-42. These appear to fit just fine. However, there was not a note about the MD36-16M rod end bearing, which is for the bottom of the rudder. It was replaced in my kit with a GMM-3M-680. The thread of the rod is correct, and it is slightly longer than the MM-3M-42’s, but it is significantly thicker and does not readily squeeze in between the hinge brackets on the vertical stabilizer.

The MM-3M-42 housing is 0.333” thick and the bearing is 0.434” thick at the flat faces where it will mount.

The GMM-3M-680 housing is 0.377” thick and the bearing is 0.500” thick at the flat faces.

The hinge brackets on my vertical stabilizer have 0.439”, 0.459”, and 0.409” clearance between them (top to bottom). The MM-3M-42 bearing fits perfectly well in all three, a little tight in the bottom one. The GMM-3M-680 is a problem.

Should I find a replacement for the bottom rod end bearing or force the GMM-3M-680 into place?
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  #2  
Old 02-16-2018, 06:28 AM
Tom023 Tom023 is offline
 
Join Date: Jul 2011
Location: Cypress, TX
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Your first step should be to call Vans. If the bearing you got matches the inventory sheet discuss the tight fit with them. If the one in the plans matches the inventory sheet it could be a mistake. I've ordered every kit for the 14 and there hasn't been one without some minor parts errors...and some major ones too
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Last edited by Tom023 : 02-16-2018 at 06:30 AM.
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  #3  
Old 02-16-2018, 09:18 AM
iamtheari iamtheari is offline
 
Join Date: Nov 2017
Location: ND
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I wrote to Van's this morning and will hope to get a reply. However, I found some specs that make it look like the replacement part and the original part are a good match, 0.5" wide at the bearing. Did anyone else have any issues with the lower rudder rod end bearing fitting between the hinge brackets on the vertical stabilizer? If it's just a tight fit and that's okay, I won't worry so much, but I don't like having to apply a lot of force to anything without triple-checking beforehand.
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  #4  
Old 02-16-2018, 11:52 AM
mturnerb mturnerb is offline
 
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Location: Ponte Vedra, FL
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I don't recall any issues with the part I received. As a reference point, I got the following part: "Bearing MD3616M". My empennage is in storage, but I do recall the lower bearing being larger overall - seems like it is thicker but don't recall specifics.
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  #5  
Old 02-16-2018, 12:23 PM
iamtheari iamtheari is offline
 
Join Date: Nov 2017
Location: ND
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Quote:
Originally Posted by mturnerb View Post
I don't recall any issues with the part I received. As a reference point, I got the following part: "Bearing MD3616M". My empennage is in storage, but I do recall the lower bearing being larger overall - seems like it is thicker but don't recall specifics.
Do you recall any difficulties in getting the bearing to fit between the two halves of the hinge bracket? The specs for the MD3616M and GMM-3M-680 are the same so the fit should be the same for the part I got as for the part you got.
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  #6  
Old 02-16-2018, 12:48 PM
Bgill Bgill is offline
 
Join Date: Sep 2017
Location: Douglas, GA
Posts: 18
Default Rudder Bearings

I checked mine just now and the upper and lower hinge brackets are .45 to .50 in spacing with the bottom also at .45”.
The bearings (upper and mid) are .436 wide with the lower being .50 inches.
Thus my lower would have a .05” spacing issue - if the brackets didn’t flex. Its a tight squeeze but it will go in. I suspect some variation in brackets forming.
Not a definite answer, but a reference point..
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  #7  
Old 02-16-2018, 02:32 PM
mturnerb mturnerb is offline
 
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Location: Ponte Vedra, FL
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Quote:
Originally Posted by iamtheari View Post
Do you recall any difficulties in getting the bearing to fit between the two halves of the hinge bracket? The specs for the MD3616M and GMM-3M-680 are the same so the fit should be the same for the part I got as for the part you got.
Nope - seemed to fit OK. As mentioned by others, a bit tight but nothing bothersome.
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  #8  
Old 02-17-2018, 11:56 AM
rvbuilder2002 rvbuilder2002 is offline
 
Join Date: Jul 2005
Location: Hubbard Oregon
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Quote:
Originally Posted by iamtheari View Post
I finally got the back ordered parts from the empennage kit today. There was a note in the hardware bag #1902, which said that the MD36-14M rod end bearings were replaced with MM-3M-42. These appear to fit just fine. However, there was not a note about the MD36-16M rod end bearing, which is for the bottom of the rudder. It was replaced in my kit with a GMM-3M-680. The thread of the rod is correct, and it is slightly longer than the MM-3M-42’s, but it is significantly thicker and does not readily squeeze in between the hinge brackets on the vertical stabilizer.

The MM-3M-42 housing is 0.333” thick and the bearing is 0.434” thick at the flat faces where it will mount.

The GMM-3M-680 housing is 0.377” thick and the bearing is 0.500” thick at the flat faces.

The hinge brackets on my vertical stabilizer have 0.439”, 0.459”, and 0.409” clearance between them (top to bottom). The MM-3M-42 bearing fits perfectly well in all three, a little tight in the bottom one. The GMM-3M-680 is a problem.

Should I find a replacement for the bottom rod end bearing or force the GMM-3M-680 into place?
Quote:
Originally Posted by iamtheari View Post
I wrote to Van's this morning and will hope to get a reply. However, I found some specs that make it look like the replacement part and the original part are a good match, 0.5" wide at the bearing. Did anyone else have any issues with the lower rudder rod end bearing fitting between the hinge brackets on the vertical stabilizer? If it's just a tight fit and that's okay, I won't worry so much, but I don't like having to apply a lot of force to anything without triple-checking beforehand.
Because of your VAF post, and because an alternate part was recently introduced, this was looked at by engineering.

The rod end bearing used at the bottom position of all RV models has always been larger overall, because a longer length is needed (a longer length is not available in the sized used at the other two positions).

The new part that you received does match the original size specs (as you already found).
The problem must be related to your lower hinge brackets.

By design, they are supposed to be further apart that the upper ones to allow for the fit of the wider bearing.

The first thing to check would be that the bend on each is 90 degrees. If they are under bent slightly, the resulting gap will be smaller than intended.
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  #9  
Old 02-17-2018, 08:38 PM
iamtheari iamtheari is offline
 
Join Date: Nov 2017
Location: ND
Posts: 155
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Quote:
Originally Posted by rvbuilder2002 View Post
Because of your VAF post, and because an alternate part was recently introduced, this was looked at by engineering.

The rod end bearing used at the bottom position of all RV models has always been larger overall, because a longer length is needed (a longer length is not available in the sized used at the other two positions).

The new part that you received does match the original size specs (as you already found).
The problem must be related to your lower hinge brackets.

By design, they are supposed to be further apart that the upper ones to allow for the fit of the wider bearing.

The first thing to check would be that the bend on each is 90 degrees. If they are under bent slightly, the resulting gap will be smaller than intended.
Thank you for this information. I took a closer look, in better light, and indeed the brackets were bent inward slightly. With the bearing between them, the opening is consistent from the spar back to the hole. That was the problem.
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  #10  
Old 02-16-2018, 12:55 PM
Aluminum Aluminum is offline
 
Join Date: Jul 2017
Location: San Jose, CA
Posts: 192
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Quote:
Originally Posted by iamtheari View Post
The hinge brackets on my vertical stabilizer have 0.439”, 0.459”, and 0.409” clearance between them (top to bottom). The MM-3M-42 bearing fits perfectly well in all three, a little tight in the bottom one. The GMM-3M-680 is a problem.

Should I find a replacement for the bottom rod end bearing or force the GMM-3M-680 into place?
The 0.1" too narrow spacing between the bottom brackets indicates a part/construction error, tolerances are two orders of magnitude tighter than this. Try and post photos.

I just finished this part and the fit was perfect, light finger pressure required to separate the brackets (by about the thickness of the powder coat) and slide in all three bearings with no interference.
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