[f-AA] A-65 Engine Mount Bushings - Lubricate the Bolts?

[Robert C Jacoby]

About to install new engine mounts on my Aeronca Champ (7AC; A-65-8). Does anyone lubricate the inside of the rubber bushings (SA22387)? The reason I ask is that the bolts are 7/16" in diameter, and the hole in the bushing is 3/8" in diameter. It's a pretty tight fit. I'm not at the hangar today, but an A&P friend who finished the same job this morning on a Chief (11AC; same motor) said that she put a light coat of silicone on the bolts and still had to drive them in with a hammer).

Related, when we removed one of the bolts on the Chief yesterday it appeared as though it had been coated with oil or grease when it was installed [many] years ago because it was still slippery - I'm not thinking that grease of any form, or a lubrication that stays slippery is desirable.

If lubrication is used I'd be inclined to use Tire Changing Paste which is slippery when applied, but will dry and not be slippery when it is dry. It's used on tires and endorsed because the tires are not inclined on spin on the rim once it is dry.

Any suggestions from experience would be appreciated.

PS: I'll attach two photos that illustrate the size mismatch. We spoke to Continental yesterday and they confirmed that this is absolutely the right rubber bushing (i.e. SA22387) and the engine mount drawing for the Aeronca 7AC clearly show that this is a 7/16 (i.e. AN7-37) bolt.

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[Mark Peterson]

Decades ago we used to soak the whole thing in silicon to try and avoid the cracking that will come in a half year or so.   Silicon was preferred.   The new rubber is very prone to cracking a at the edges of the mount.  As long as the inner hole isn't cracked, the cracking is cosmetic.  Many people replace them only to find that it was only the other surface on the flange .that looked bad.

Mark

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From: aer...@westmont.edu <aer...@westmont.edu> on behalf of Robert C Jacoby <robert...@gmail.com>
Sent: Thursday, January 22, 2026 12:23 PM
To: aer...@westmont.edu <aer...@westmont.edu>
Subject: [f-AA] A-65 Engine Mount Bushings - Lubricate the Bolts?

 

[Richard Murray]

Well I just put eight new Superior rubber bushings on my TC for its A-65 in 20 degree temps and warmed them in front of a propane torpedo heater before applying a little penetrating oil to the bushing and bolt.

Richard in OH where single digit temps are going to keep me ar home for the next week.

[Andy Lumley]

I've replaced those bushings many times and I think silicon works best and what I use is Silicone Paste Dielectric Grease that I bought from Amazon which I think works much better than the spray. Can't remember exactly how I found them but there are non Superior versions available which seem to last longer, they might have been OEM.

Best rig I've used for the job btw is a engine hoist, the portable kind, makes the job go very easy once you get the engine balanced.