Dave,
 
on shimmy.
 
This is most often caused by one of three things: Most likely the sissors 
linkage being loose.
 
1,Out of balance nose wheel
       
     rremove and balance
 
2 loose linkage on the sissors.
     the bolts holding the sissores to the nose assy must be properly tightened.
     the sissors should have a serrated washer (2) between the sissors and the 
mount. The washer locks the sissors against the bushing that is inside the 
mount, making the bushing move as the sissors opens and closes, and does not 
let the sissors move against the bolt.
Often I have seen mechanics think the sissors must be loose enough to move, and 
they leave the bolt loose to allow this. The bolt wears the hole in the 
sissors, allowing shimmy.
Fred designed the system so the bolt against the sissors, locks the sissors to 
the bushing by the serrated washer, using the bushing as wearing/replaceable 
part, preventing loosness on the sissors, and preventing shimmy. see Ercoupe 
Parts book, page 20/21a, fig 12/12a, items 34, 50, 43, etc...
 
3.  Loose bearings in the wheel. 
If you have a single fork system, the wheel has a single bearing, that is a 
special pre-loaded bearing, with no play. Replacing it with a similar numbered 
bearing ( but not special preloaded type) results in play in the wheel to 
bearing , and results in shimmy.
   Replace bearing with proper pre-loaded bearing...See page # 40 Ercoupe 
Service Manual, para4, last sentence.  "This deep groove preloaded......"
 
Hope the above helps...
 
Fly Safe - Have Fun
 
Harry Francis
  
 


--- On Thu, 1/8/09, David Winters <[email protected]> wrote:

From: David Winters <[email protected]>
Subject: RE: [ercoupe-tech] LOOKING FOR ADVICE re venturi
To: "'John Cooper'" <[email protected]>, [email protected]
Date: Thursday, January 8, 2009, 10:53 AM








Shucks,
 
Back to the shop she goes.  The DG is OOC.  So I said to remove it.  BUT, the 
A&P is afraid to remove the DG and leave only the Attitude Indicator on the 
venturi.
I have a BIG (4 inch) venturi, and he thinks it will overpower, over-spin, and 
destroy the solitary attitude indicator.
I LIKE having the attitude indicator, so I do not care to remove it.  Is he 
correct?  (He admits he is only guessing.)
 
Anybody have a smaller venture for sale?  (I have no idea how much trouble it 
is to install one.) 
  
The bird had her nose gear all reconditioned, but still shimmies on landing 
roll-out like a fresh burlesque queen.  Any theories as to what to do to fix it 
are welcome. 
  
Dave W 














      

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