912UL rubber engine mount replacement

[Jesse]

I just resurrected my grandfathers model 5 kitfox as it has sat in his hangar unused for 15 years and have been doing a lot of little work as i keep noticing new items that are needing to be fix/replaced. The most recent being the rubber engine mounts. The 2 upper mounts look fine to me and don't feel hard or appear cracked but he 2 lower ones look to be sagging. This is a picture of one of them. Engine runs normal idols fine at 1800 rpm but wondering if this is cause for replacement. Seams like i fly for an hr then spend a 2 weeks fixing little things and then repeat the process. Anxious to hear what people have to say on this topic. Thanks all!!

[Jesse]

The other lower mount.

[Dave S]

Jesse,

Haven't seen any responses.....don't know that I can answer your question with certainty; but, two things that can be considered are the age and sagging.

If you have the installation manual; take a look at the Vibration Isolator detail which shows a cross section of the engine mount socket and the parts that make up the assembly. A point to keep in mind is the engine mount socket has a smaller diameter in the center of the mount than what you see on the outside.....if there is enough sag/wear....it isn't beyond possibilities that metal to metal contact could occur between the minor diameter of the engine mount socket and the metal bushing that the bolt goes through.

I remember it being a bit of a challenge to get enough compression on the rubber mounts to get the nut started on the bolt on my build when everything was new - probaby due to compressing the rubber hose bushing that goes between the front and back Lord rubber bushing.

Keep your spirits up on the maintenance stuff you are finding.....

Sincerely,

Dave S
KF 7 Trigear
912ULS Warp drive

St Paul, MN

[Paul Z]

I'll be at the Airport to morrow to work on my plane it is a SLSA, I get a comparison picture of my bushings. Mine are 5 years old.

[happiestflying]

Just purchased a Kitfox IV Speedster with the 912 ULS, and the first thing I noticed during the pre-buy inspection was these mounts. Mine are much more worn than the photos here, yet there doesn't seem to be any sag. It was a judgement call on the purchase, but I had read this thread by a complete fluke a few days before I bought the plane.

I guess this is going to be the first major repair that I'll be taking on, other than that we rebuilt both carburetors before I flew it home 1100 NM from Canon City Colorado to the Seattle area. That solved some major discrepancies in EGT's and lack of full power and rough running.

Ran like a champion all the way home. Thanks to Cory Thompson at Fremont County Airport (1V6) for taking on the carburetor task.

[Paul Z]

I'll be at the Airport to morrow to work on my plane it is a SLSA, I get a comparison picture of my bushings. Mine are 5 years old.

Here is a photo of my plane only 5 years old. I'll post another in a second post.

[Paul Z]

I'll be at the Airport to morrow to work on my plane it is a SLSA, I get a comparison picture of my bushings. Mine are 5 years old.

Second photo

[Spook712]

Hi Jesse,


I bought a 20year old Sries 5 and have the same situation(if not more pronounced sagging wise).


Could you post what you did to fix it if it had to be fixed.


Pauls Engine Mounts look a lot mor "in line".


Thanks,
TUNA

[DesertFox4]

Jessie hasn’t logged into this site since May 2016.