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  #1  
Old 03-31-2018, 12:13 PM
JDA_BTR JDA_BTR is offline
 
Join Date: Dec 2013
Location: Baton Rouge, LA
Posts: 604
Default Engine mount wrong?

The upper corners of my engine mount seem wrong. There is 1/2 ID tube where I think there should be 3/8 so the bolt wallows around. Also an AN6-24 is too short. Any ideas? I asked Vans already but quicker answers here!!!





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  #2  
Old 03-31-2018, 12:20 PM
rvbuilder2002 rvbuilder2002 is offline
 
Join Date: Jul 2005
Location: Hubbard Oregon
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It is purposely over sized.
The only hole diam. that matters structurally is the one in the flange that mates with the firewall.
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  #3  
Old 03-31-2018, 01:14 PM
Jake14 Jake14 is offline
 
Join Date: May 2014
Location: Seattle
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hard to tell with the angle, but it looks like my (14A) upper left tube might be shorter than the one in your pic, but upper left and right bolts are AN6-26A on the taildragger

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Last edited by Jake14 : 03-31-2018 at 01:29 PM.
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  #4  
Old 03-31-2018, 01:31 PM
JDA_BTR JDA_BTR is offline
 
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Scott, is there some manuf variability in the depth of that mount tube? My right and left upper corners both need a 25 or 26. The plans are usually dead on. I for sure have the right bolt sized it on the size chart.
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Last edited by JDA_BTR : 03-31-2018 at 01:34 PM.
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  #5  
Old 04-02-2018, 12:30 PM
rvbuilder2002 rvbuilder2002 is offline
 
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Quote:
Originally Posted by JDA_BTR View Post
Scott, is there some manuf variability in the depth of that mount tube? My right and left upper corners both need a 25 or 26. The plans are usually dead on. I for sure have the right bolt sized it on the size chart.
The production drawing shows that the upper two bushings should be 1.25" long (beyond the face of the flange washer), and the lower 4 bushings should be 1.0" long.

I have not heard of any other complaints about the specified bolts being too short.
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  #6  
Old 04-04-2018, 02:56 PM
JDA_BTR JDA_BTR is offline
 
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Location: Baton Rouge, LA
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Measured my upper mount bushings and mine measure just shy of 1.5 inches past the big washer or 1-5/8 from the firewall. Thatís an extra 1/4 too long. So do I just upsize the bolt length or get another mount?
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  #7  
Old 04-10-2018, 06:20 PM
JDA_BTR JDA_BTR is offline
 
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Final answer on this was the tube diameter is right but my tube is 1/4 too long. Up two bolt sizes and carry on I was told.
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  #8  
Old 04-10-2018, 06:42 PM
Jake14 Jake14 is offline
 
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maybe someone welded a taildragger tube on a tri-gear mount. taildragger upper tubes are longer for some reason
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  #9  
Old 08-19-2018, 05:05 PM
Stockmanreef Stockmanreef is offline
 
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Location: Midland, mi
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How much of the bolt should stick through the firewall? What is the minimum amount of threads that should show on the end of the bolt after torquing down the nuts?

My upper bolts seem to too short like stated above. I have about 1 thread showing before torquing down on the bolts.

The lower bolt will have lots of exposed thread.
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  #10  
Old 08-19-2018, 05:12 PM
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RV-14E RV-14E is offline
 
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Quote:
Originally Posted by Stockmanreef View Post
How much of the bolt should stick through the firewall? What is the minimum amount of threads that should show on the end of the bolt after torquing down the nuts?

My upper bolts seem to too short like stated above. I have about 1 thread showing before torquing down on the bolts.

The lower bolt will have lots of exposed thread.
Page 5-18:

"A common rule of thumb for evaluating whether an installed bolt is the proper length has always been that up to three thick washers are allowed (if more than three are needed the next shorter bolt should be used), and that at least one but no more than three full threads of the fastener are to be showing beyond the nut. This rule of thumb works for the AN365 nuts that have been commonly used on RVs for years.

Some of the newer RV kits use the all metal MS21042 self locking nut. The long standing rule of thumb will not work for these nuts because they are shorter in height than the AN365 nut. For these nuts, modify the rule of thumb to ďat least three, but not more than five threads showing.Ē This rule of thumb will still allow for meeting the 'maximum use of three washers' rule.

You may have to educate any technical councilors or airworthiness inspectors that perform inspections on your project. Some
inspectors are not familiar with these smaller sized nuts."
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