Motor Mount-ing

[Andy Walker]

Hey all...

I spent all day shimming, aligning, and measuring my motor mount. All said and done, my mount seems to be sitting about 1/10" high, and about 1/8" forward of the plans position. The issue I have is that the lower mounts are as far back and as low as they can go.

The mount is nice and square in every direction I can measure. I just don't know if these amounts are going to cause problems. Should I accept these deviations, or should I think about grinding some material off the back and bottom of the lower mounts to make it meet factory location exactly? I hate to ruin that nice powder oat, but I will if necessary.

Andy

[N111YX]

Up late at night worrying...:)

I would not sweat those tolerances.

[Mike53]

When I get to that stage on the Onex ,I will be jumping for joy that it is that close to plans.Pat yourself on the back for a job well done 8-)

[Andy Walker]

Up late at night worrying...:)

I would not sweat those tolerances.

Cool. I just don't want to get the cowl on and realize it doesn't fit. It looks pretty good to me, but I've been fooled before, and I don't want to have to buy another motor mount at $1000. :shock:

[Andy Walker]

When I get to that stage on the Onex ,I will be jumping for joy that it is that close to plans.Pat yourself on the back for a job well done 8-)

With all the match drilled parts and pre-cut/bent channel pieces in your kit, you'll probably be a lot closer to spec all around than I am! 8-)

[Mike53]

When I get to that stage on the Onex ,I will be jumping for joy that it is that close to plans.Pat yourself on the back for a job well done 8-)

With all the match drilled parts and pre-cut/bent channel pieces in your kit, you'll probably be a lot closer to spec all around than I am! 8-)

We Onex owners are a special breed ....yeh know we can also flap our wings :mrgreen: ;)

[Andy Walker]

Argh!!! Kip got a panicked call from me today after I drilled my first hole... Turns out to keep everything perfectly 90 degrees (meaning mainly the motor mount pins at the front of the mount) I had to pull the upper part of the mount a little too far away from the firewall (even though I carefully measured and it looked okay before drilling), resulting in a pilot hole that when drilled to size will only be 1.5D from the edge, drilled to full size it would be 1D from edge of hole to edge of plate. Assuming the 2D rule applies to steel as well as aluminum, this looks uncool. Here's the pic (this is upper left mount plate, measured from hole center to back edge):



So I have the following options:

1) Carry on -- steel is really strong and this is not an issue...the 2D rule really doesn't apply strictly here, and 1.5D is plenty.

2) Try to offset the hole with progressive offset updrilling -- tricky.

3) Push the upper mounts back about a 1/16" to buy more distance then offset the hole -- this will make the mount sit about a quarter to a half degree off of perfectly 90 degrees on all the mounting pins, but that may not be enough to even notice. Offset updrilling still tricky.

4) Take the mount to a welding shop, have them fill in/repair/grind flush the existing hole, then start over. In order to avoid the same problem I'd probably have to reposition the mount as in #3.

5) A combination of the above or something else I didn't think of.

Any comments? I sent all this info to Sonex to get their opinion. Sheesh, seems I can't do anything right on this damn build, no matter how long I spend. :oops:

Andy

Andy

[MichaelFarley56]

I wish I had a good answer for you but my advice is to see what the factory says tomorrow. I'd like to hope this isn't an issue but I'm not an engineer. Hopefully it's still fine...

Let us know what they say!

[Andy Walker]

I wish I had a good answer for you but my advice is to see what the factory says tomorrow. I'd like to hope this isn't an issue but I'm not an engineer. Hopefully it's still fine...

Let us know what they say!

Will do Mike. I'm thinking now if there's any hesitation on the part of the factory, I'll just take it to a welder and have it fixed. Then I can start over, push it in tight, and just deal with the half degree vertical offset, which is probably not a problem anyway. :|

[Andy Walker]

Got this from Kerry this morning:
-- ----------------
That hole will be OK.
You can move the other hole in if you want, or add a third hole in-between the regular two as a feel-good measure if you wish.
The Sonex only needs one bolt per corner but we have two because that makes people feel more comfortable.
------------------

The only question now is: third bolt or not? I'm leaning toward a third bolt between and inward from the existing two holes. That would be the ultimate "feel good" on this I think. Stronger than the plans at the cost of ten minutes and two bolts and nuts. Any other opinions on this?