REFLECTOR: Replacing rubber engine mounts

Mark Magee edjonesbrady at gmail.com
Fri Sep 7 23:25:44 CDT 2012


Are there not silastic silicone mounts for our LYC/CONTs?

http://www.dowcorning.com/content/jtbd/jtbd_noise_vibration_harshness.aspx

There are numerous articles on 'stiffening' aging automotive engine mounts if you Google 'silicone engine mounts'.



Mark B. Magee
N34XL
Sent from IPhone 4S

On Sep 7, 2012, at 8:35 PM, David Rene Dugas <renedugas at gmail.com> wrote:

> I was told years ago 3/16 " in first five years then very little until they begin to disintegrate. Mine is 10 years out since the engine was hung and measuring from spinner to upper cowl that once matched that is about right. Lycoming IO-540. XL RG. 600 hrs. 
> 
> Rene' Dugas
> Sent from my iPhone4S
> 
> On Sep 7, 2012, at 7:17 AM, Reiff Lorenz <Reiff at lorenz.com> wrote:
> 
>>  
>> >> do the rubber engine mounts settle with age?  Is there a published service/replacement period for the mounts?<<
>>  
>>  
>> Fred,
>>  
>> This month's EAA Experimenter has an article on rubber engine mounts. Here's the link to the full issue:
>> http://experimenter.epubxp.com/i/81495
>>  
>> Here is an excerpt:
>> >> 
>> In the certificated world, mounts are usually changed at
>> overhaul time. For our experimental aircraft the annual
>> condition inspection is a great time to check mounts . . . .
>>  
>> As a natural rubber mounting ages, its surface will
>> become covered with a waxy film. This protects against
>> ozone, UV, and some contaminants. Leave it on!
>> Old mounts may sag. You’ll notice this when the
>> spinner doesn’t line up with the cowl the way it used
>> to. Mounts also compress over time. When they do, the
>> original spring rate changes, and when the spring rate
>> changes, the performance of the mount changes. When
>> the mount’s performance changes, it’s usually not for
>> the better. . . .
>>  
>> If you notice your mounts getting hard or suddenly shiny, they
>> may be cooked. Replace them. Rubber parts on aircraft
>> that live in very hot, very dry, or very sunny areas tend
>> to deteriorate faster.
>> << 
>>  
>> Hope this helps!
>>  
>>  
>> Reiff Lorenz, Dayton, OH
>> Velocity XL-RG, 36% complete
>> Currently working on: Pressure testing fuel and oil hoses.
>>  
>>  
>> The Velocity Builders' Virtual Hangar. Available 24/7 for builders and owners:
>> https://liveconferencepro.com/guest/loginguest.php?id=86a48563bb517ade0abf1a7ee1f38e65
>>  
>>  
>>  
>> -----Original Message-----
>> From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On Behalf Of Fred Anderka
>> Sent: Thursday, September 06, 2012 11:26 AM
>> To: reflector at tvbf.org
>> Subject: Re: REFLECTOR: Oil cooler clearance (Don Johnston)
>>  
>> Hi Don:
>>  
>> I can't recall how much clearance I had initially, it may have been about 3/8".  What caught my attention was that the powder coating on the engine mount had been chipped and there was an abrasion mark on the corner of the oil cooler.  After adding the washers on the top of the right side rubber mounts there is about 5/8" clearance.
>>  
>> Tape a small piece of PlayDo on the engine mount tube that will show if the oil cooler is still contacting that tube.  As the engine turns counter clockwise (looking from the back) the torque reaction will tend to close the oil cooler/engine mount tube gap.  I have no idea how much the torque reaction twists the engine during maximum power T/O.  Another question; do the rubber engine mounts settle with age?  Is there a published service/replacement period for the mounts?
>>  
>> Fred
>> XL-RG (620 hrs.)
>>  
>> Date: Wed, 5 Sep 2012 17:05:54 -0500
>> From: Don Johnston <numa at comcast.net>
>> To: reflector at tvbf.org
>> Subject: REFLECTOR: Oil cooler clearance
>>  
>> Groan...
>>  
>> Fred,
>>  
>> How much clearance is needed to not hit the mount during startup and shutdown?
>>  
>> Don
>>  
>>  
>>  
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