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engine mount washers

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Charles Heathco

Joined: 10 Jan 2006
Posts: 201

Posted: Mon Nov 02, 2009 3:28 am Post subject: engine mount washers

Thanks for the info re washers, now who is the math  whiz that knows how thick the washer should be to raise the front 3/8"? I heard  mention of cutting a slot to enable sliping behind mount, anyone done this?  

   [quote][b]

pitts_pilot(at)bellsouth.
Guest

Posted: Mon Nov 02, 2009 5:16 am Post subject: engine mount washers

charlie heathco wrote:

 	  Quote: 	
		   Thanks for the info re washers, now who is the math whiz that knows how 

 thick the washer should be to raise the front 3/8"? I heard mention of 

 cutting a slot to enable sliping behind mount, anyone done this?

I can't help with the math, but my comment is ..... what can slip in 
	


.... can slip out.

Linn

do not archive



 	  Quote: 	
		   

 *

 

 

 *

pitts_pilot(at)bellsouth.
Guest

Posted: Mon Nov 02, 2009 5:50 am Post subject: engine mount washers

Changed my mind.  Measure from the floor to the prop.  Measure how much 

you want to lift the engine.  Pull the lower isolator bolts and shim 

until you get the sum of the two measurements.  Best I can offer.

Linn

Linn Walters wrote:

 	  Quote: 	

 charlie heathco wrote:

> Thanks for the info re washers, now who is the math whiz that knows 

> how thick the washer should be to raise the front 3/8"? I heard 

> mention of cutting a slot to enable sliping behind mount, anyone done 

> this?

 I can't help with the math, but my comment is ..... what can slip in 

 ..... can slip out.

 Linn

 do not archive

>

> *

> *

Kellym

Joined: 10 Jan 2006
Posts: 1705
Location: Sun Lakes AZ

Posted: Mon Nov 02, 2009 7:03 am Post subject: engine mount washers

Not when supporting 300+lbs of engine, with slot to the bottom. Standard 

industry practice.



Linn Walters wrote:

 	  Quote: 	
		   


	


 	  Quote: 	
		   I can't help with the math, but my comment is ..... what can slip in 

 ..... can slip out.

 Linn

 do not archive

_________________
Kelly McMullen
A&P/IA, EAA Tech Counselor # 5286
KCHD

pitts_pilot(at)bellsouth.
Guest

Posted: Mon Nov 02, 2009 8:13 am Post subject: engine mount washers

Kelly, I find that troublesome .... it may be standard practice ..... 

but I stand by my comment.  When the airplane is flying, all the engine 

weight isn't on the isolators, and where the washers go .... it can 

become looser and conceivably work it's way out.  No real problem 

if/when it does, but I don't see why you'd slot the washer just to save 

a little time.  Well, if you're wrenching for a living ......

Linn

Kelly McMullen wrote:

 	  Quote: 	

 Not when supporting 300+lbs of engine, with slot to the bottom. Standard 

 industry practice.

 Linn Walters wrote:

> 

> I can't help with the math, but my comment is ..... what can slip in 

> ..... can slip out.

> Linn

> do not archive

John Myers

Joined: 10 Jan 2006
Posts: 11
Location: Cedar Bluff, AL

Posted: Mon Nov 02, 2009 9:21 am Post subject: engine mount washers

Kelly, Lynn, others,



This may be a dumb question, but wondering if everyone is talking the same 

location for washers.   I have seen washers mounted under isolation mounts 

as it seems most are talking about but I have also seen 970's added under 

the engine mount to firewall gussets.  I have used both locations for 

different purposes.  One to reposition the isolation mount geometry and one 

to reposition the whole mount and engine.  I know of one occasion where the 

spacer inside the mount was reduced in length to tighten up the isolation 

mount.  I would think they present different problems and or solutions.  The 

engine tends to change it's weight on the mounts during flight and moves 

around a lot during cranking, shutdown and anything other than 1 G flight. 

On the other hand the mount to firewall fit is more rigid and tends to stay 

where you bolt it.  However a loose bolt or lost washer at that location is 

possibly more troublesome as the bolt size there may not be sufficient, 

given the abuse that occurs when they are loose.



I also have a sagging engine and was planning on going with one or two 970's 

between the mount and firewall, but also realize that in flight the engine 

may not be sagging as much.  It seems that most commenting on this thread 

are putting a 970 washer under the isolation mount but I don't see how that 

will tighten up the isolation mount without treating the internal spacer.



I don't do any negative G stuff (on purpose anyway) and generally never 

exceed 3 to 3.5 G positive but the engine still moves around a lot with 

gyroscopic actions as well as simple G loads.  Is the concensus that short 

of changing out the mounts, the best approach is to washer up the isolation 

mounts?  I know the best solution would probably be to replace the kit iso 

mounts with Lord mounts but what is the consensus for next best solution.



John Myers with a little sag with a 360 on an 8

pitts_pilot(at)bellsouth.
Guest

Posted: Mon Nov 02, 2009 12:25 pm Post subject: engine mount washers

John Myers wrote:

 	  Quote: 	
		   

 

 Kelly, Lynn, others,

 

 This may be a dumb question,

It'll be the first one!  <GR>
	




  but wondering if everyone is talking the

 	  Quote: 	
		   same location for washers.   I have seen washers mounted under isolation 

 mounts as it seems most are talking about but I have also seen 970's 

 added under the engine mount to firewall gussets.  I have used both 

 locations for different purposes.  One to reposition the isolation mount 

 geometry and one to reposition the whole mount and engine.  I know of 

 one occasion where the spacer inside the mount was reduced in length to 

 tighten up the isolation mount.  I would think they present different 

 problems and or solutions.  The engine tends to change it's weight on 

 the mounts during flight and moves around a lot during cranking, 

 shutdown and anything other than 1 G flight. On the other hand the mount 

 to firewall fit is more rigid and tends to stay where you bolt it.  

 However a loose bolt or lost washer at that location is possibly more 

 troublesome as the bolt size there may not be sufficient, given the 

 abuse that occurs when they are loose.

The mount bolts are not as accessible (like on the inside) as the 
	


isolators, so I typically work on the isolators.  Putting washers under 

one or two of the airframe bolts also stresses the steel mount.  Just MHO.

 	  Quote: 	
		   

 I also have a sagging engine and was planning on going with one or two 

 970's between the mount and firewall, but also realize that in flight 

 the engine may not be sagging as much.  It seems that most commenting on 

 this thread are putting a 970 washer under the isolation mount but I 

 don't see how that will tighten up the isolation mount without treating 

 the internal spacer.

The washer goes forward of the isolator and the flat on the engine 
	


mounting ears if you have the ring type isolator mounts.  On mounts 

where the isolator is cone shaped and sandwiches the mounting ear, then 

the washer will be behind the isolator.

 	  Quote: 	
		   

 I don't do any negative G stuff (on purpose anyway) and generally never 

 exceed 3 to 3.5 G positive but the engine still moves around a lot with 

 gyroscopic actions as well as simple G loads.  Is the concensus that 

 short of changing out the mounts, the best approach is to washer up the 

 isolation mounts?  I know the best solution would probably be to replace 

 the kit iso mounts with Lord mounts but what is the consensus for next 

 best solution.

 

 John Myers with a little sag with a 360 on an 8

I'd use the washer method before spending so much money on new 
	


isolators.  I've seen no difference in who makes them .... in my limited 

experience.  I think the consensus is ..... whatever you prefer.  No 

matter what route you take, the end result should be the same.   Best of 

luck.

Linn



 	  Quote:

Kellym

Joined: 10 Jan 2006
Posts: 1705
Location: Sun Lakes AZ

Posted: Mon Nov 02, 2009 2:21 pm Post subject: engine mount washers

The washers are clamped in place by the engine mount bolts with locking 

nuts. No way for them to work loose. I've heard similar arguments about 

certain aircraft tiedown rings that aren't secured by anything other 

than the tightness of the threads and torque applied. Haven't seen one 

fall out yet.

Linn Walters wrote:

 	  Quote: 	

 Kelly, I find that troublesome .... it may be standard practice ..... 

 but I stand by my comment.  When the airplane is flying, all the engine 

 weight isn't on the isolators, and where the washers go .... it can 

 become looser and conceivably work it's way out.  No real problem 

 if/when it does, but I don't see why you'd slot the washer just to save 

 a little time.  Well, if you're wrenching for a living ......

 Linn

 Kelly McMullen wrote:

> 

>

> Not when supporting 300+lbs of engine, with slot to the bottom. 

> Standard industry practice.

>

> Linn Walters wrote:

>> 

>

>> I can't help with the math, but my comment is ..... what can slip in 

>> ..... can slip out.

>> Linn

>> do not archive

>

_________________
Kelly McMullen
A&P/IA, EAA Tech Counselor # 5286
KCHD

mcculleyja(at)starpower.n
Guest

Posted: Mon Nov 02, 2009 3:32 pm Post subject: engine mount washers

Another viewpoint based on experience with the slotted-washer spacers (& 

slot downward).

I placed 1/8 inch thick ones behind the two lower mounts and one stayed 

in place without problems. The other one gradually worked upward in 

about 10 hours time. After twice putting it back in proper location and 

seeing it creep up each time, I finally added a drop of CA glue between 

the surfaces and no problems to date after another 200 plus hours.

Jim McCulley

============================================================================================

Kelly McMullen wrote:

 	  Quote: 	

 Not when supporting 300+lbs of engine, with slot to the bottom. Standard 

 industry practice.

 Linn Walters wrote:

> 

> I can't help with the math, but my comment is ..... what can slip in 

> ..... can slip out.

> Linn

> do not archive

rice737(at)msn.com
Guest

Posted: Mon Nov 02, 2009 5:23 pm Post subject: engine mount washers

Anyone who has done this C

  

 With reference to adding washers between the engine and the mount C did you have to get longer bolts as well?  It looks like the cotter pin hole would be covered up if I add even a thin washer.

  

 Paul Rice

 RV8 180 hours

 

[quote] Date: Mon C 2 Nov 2009 18:29:07 -0500

 From: mcculleyja(at)starpower.net

 To: rv-list(at)matronics.com

 Subject: Re: engine mount washers

 

 --> RV-List message posted by: "J. Mcculley" <mcculleyja(at)starpower.net>

 

 Another viewpoint based on experience with the slotted-washer spacers (& 

 slot downward).

 

 I placed 1/8 inch thick ones behind the two lower mounts and one stayed 

 in place without problems. The other one gradually worked upward in 

 about 10 hours time. After twice putting it back in proper location and 

 seeing it creep up each time C I finally added a drop of CA glue between 

 the surfaces and no problems to date after another 200 plus hours.

 

 Jim McCulley

 ==========================================

 

 Kelly McMullen wrote:

 > --> RV-List message posted by: Kelly McMullen <kellym(at)aviating.com>

 > 

 > Not when supporting 300+lbs of engine C with slot to the bottom. Standard 

 > industry practice.

 > 

 > Linn Walters wrote:

 >> --> RV-List message posted by: Linn Walters <pitts_pilot(at)bellsouth.net>

 > 

 >> I can't help with the math C but my comment is ..... what can slip in 

 >> ..... can slip out.

 >> Linn

 >> do not archive

 > 

 > 

 > 

 > 

 >==============

 

 

 

 		 	   		     	  Quote: 	
		  [b]

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