Motor mount weirdness

[Christian]

I'm working on a Fury Extreme that I bought used (I hate buying used, won't do that again) and an Expert that I'm upgrading to an Extreme. I'm using YS 91's in both, so I'm working with the 8.45 ratio. From chatting with David Harkey in helichat, he mentioned that the 8.45 motor mounts are .030" shorter than the 8.18/9.3 mounts. I planned on taking my Expert mounts and milling that amount off them.

Here's where it gets weird. The Extreme I bought, the motor mounts are the same size (within .004") as the Expert and he was using a .020" shim on each side. When I hang the motor in place, the motor mount pushes the motor at an angle, so it appears that the previous owner changed everything except the mounts (don't know how to explain the shims). The Expert mounts measure 2.200" high and the mounts in the Extreme measure 2.196" high.

What do you think is going on? Thanks

[lawrenmd]

I have a similar issue with the Fury I am flying now. It was a new kit, when I hung the motor for the first time I could not get the gap egual to the fan. The motor needed to move back about .020 to allow the gap to close up at the rear. I cut a couple of .020 shims from aluminum stock and now it aligns perfectly. I 'm not sure what mounts I have, the kit was for the 8.45 ratio. Something could be going on with tolerances on the frame and the mounts?

[DavidH]

The 8.45 mounts 119-50 and 51 have a square hole in the side of the mount.

The normal Fury mounts 9.3 and 8.18 ratio 115-50 and 51 have a round hole in the side of the mount.

The 8.45 mounts are .030 less than the normal Fury mounts.

The 119-50 and 51 mounts is what comes in the Tempest. They are used for all gear ratios in the Tempest.

David

[kthane]

Some of the earlier 8.45 had round holes. I happen to have some :smokin:

P.S.
What's with quiznos cancer infested rat picture, Christian? :shock:

[DavidH]

Your correct,
The first few 8.45 mounts had round holes when the Extreme first came on the market. They can be identified by the face where the motor will mount will be raw aluminum and not be anodized black. The reason they were this way is they were normal mounts that had .030 machined off the mounting face.
Christian knows that , because I told him during one of our chat conversations.

[Christian]

Yep, and I pulled out the Expert mounts and they had raw aluminum on the mounting face, so it was a bit confusing. Looks like the Extreme had the Expert mounts in them, both models are older models. That would probably explain why the dampeners looked the way they did ;)