9-Series Ring Mount (Suspension Frame) Rubber Mounts

"My Zenith 701 FWF kit came with steel sleeves to make it work." 

I would love to know the source of those sleeves. Maybe Zenith will sell me a set.

Hi John,

"..............has to have a way to attach it to a motor mount."

I don't know what you mean by "motor mount" - the ring mount is attached to the engine (motor?) by 4 bolts (no rubbers)

The ring mount attaches to the airframe via 4 rubber isolator (rubber) mounts.

"I don't know what you mean by "motor mount" - the ring mount is attached to the engine (motor?) by 4 bolts (no rubbers)

The ring mount attaches to the airframe via 4 rubber isolator (rubber) mounts."

If you look at the Onex photo you posted, the black part is what I refer to as the "motor mount" which is distinct from the "ring mount" in white. The rubber isolators (i.e., the J3608) isolate the ring mount from the motor mount. If you use the ring mount, the isolators must necessarily be contained in a cylinder/cup/fitment that is integral to the motor mount.

I don't know why Rotax recommends an isolator (J3608) that is not bolt compatible with their ring mount. I also think it would have been wiser for them to choose an isolator that can be contained in a cylinder/cup/fitment that already exists (e.g., a common dynafocal cup) instead of forcing the aircraft manufacturer or homebuilder into creating something for an isolator that was never designed for fitment within/surrounded by any motor mount part that ever existed. The J3608 was designed to fit in/be surrounded by an engine case cast hole which we must recreate and attach to the motor mount if we want to use their recommended isolator.

My point is it is a poor choice for an isolator recommendation and I'm searching for better ones,  but I don't want to be, nor am I trained to be, the one to test the suitability of a bunch of isolators to find one that is appropriate for the 912's unique vibration signature. So I'm stuck with the one that Rotax recommends unless somebody out there in Rotax-Owner land has an alternative that works.

If anyone does, I'm all ears. And that is the reason I started this topic.

 Thanks for clearing that up John. I just think of the "black part" as part of the airframe but see your point.

From the photo, I posted, it would seem that the builder has come up with his own solution to your problem - off the shelf isolators, enclosed in purpose built "cups" - looks good.

I had problems with my Sonex supplied Rotax adapter system - I have gone to stiffer durometer isolators. The vibration specialist people, I went to for the parts, were incredibly helpful/knowledgeable - I am sure you could find a similar service provider in the USA.

From the photo, I posted, it would seem that the builder has come up with his own solution to your problem - off the shelf isolators, enclosed in purpose built "cups" - looks good.

Yes, his installation is very clean and he is a very helpful, friendly guy. Unfortunately he is not completely happy with the choice of rubber mount (conical, for Lycoming) as they are a bit stiff. 

So if anybody else is using an off the shelf isolator that they like, please share!