Hardware replacement during engine install

[UrbanM]

Dear A Team,
The engine on my 6A is out for IRAN and depending on how bad the backlog for parts at Lycoming is (I've been warned it's bad) I may get it back someday. In the meantime, I am cleaning up everything on the firewall, Flushing oil lines, New cable end caps, Aviation grade clamps and zip ties, Etc..
Wondering if I should replace the upper engine mounting biscuits (Not to apparent in the pic but one side looks like it has taken a set from 16 years for weight) and the prop hardware. The galling looks mild compared to some of the videos on YouTube but I figure these should be replaced during any prop removal anyways. Is it normal to just trash the bolts and replace with new?
Thanks,
Kirk

[Stevea]

Just went through the engine shock mounts on mine after 1000 hrs flying (8 yrs flying, 6-7 building after hanging the engine). I replaced them because the engine sag was beginning to cause nose gear leg to filtered air box contact while running. Upon removal, the shock mounts had noticeable sag to them.

If I were you, I'd replace all parts on all 4 mounts with new. For one thing, the shock mounts come as a set (not sure you can get only half of it). For a second, ALL the rubber in your parts is 16 years old....and age as well as temperature exposure (ie: flying) causes the rubber to harden and loose its elasticity. They may look ok, but do not have the same vibration isolation characteristics as when new. Besides, the last thing want to have happen is to have the old half of the mount fail (ie: rubber split or something similar) after replacing the other part of it.

The bolts look ok from the photos....but you might consider a new set, mostly because the new design from Van's uses metal lock nuts instead of castle nuts with cotter pins.......waaaayyyyyy easier to install. (Well, if changing shock mounts can be considered easy. )

FYI, Van's had the shock mounts (both brands, Barry and Lord) and bolt set in stock when I ordered about 3 months ago. Could be different today, but these did not (at the time I ordered ) seem to be hit by supply chain issues.

[UrbanM]

Steve,
Thanks for the reply. The seller/builder shimmed the engine mount sometime before I bought the plane (Log entry and small plates on the lower mounts to the firewall which I assume are the shims). He explained this was to counter the sag due to age. Vans shows the new bolts you mentioned and only the Lord mounts at 209 per. It looks like I have the Barry mounts which are a bit cheaper and available on AS. I've read that the Lord mounts are better for vibration. Smooth is good and I'll pay the difference if it is noticeable.
Kirk

[Stevea]

Yea, shimming will extend the life of the mounts for a bit longer....not sure how much longer since I opted to replace them.

I did make the change this time from the original (supplied with the firewall forward kit) Barry mounts to the more "spendy" Lord mounts. I have not seen (felt really) any change in airplane vibration with the new mounts.....but, my engine/prop was dynamically balanced way back at something less than 100 hours flight time.

The Lord mounts may help with better vibration isolation, I can't say. But ya should still balance the engine/prop combination. Vibration isolation (ie: the shock mounts) will only buy so much reduction in airframe vibration. Vibration elimination, by balancing, means the shock mounts have less vibration to deal with in the first place.

And of course, these days you go with whatever is in stock and available. Take the Lord mounts if that is all Van's has right now.