SonexBuilders.net

Hey all...

I know a lot of folks have to shim their motor mounts...but what size shims are we talking here? My lower motor mounts fit tightly (almost too tightly), and my uppers have a really big gap. Even when I make sure the width at the top is the specified 32", the gap between the mount brackets and the mount itself is easily 1/8" or more on each side. The only way I could get it to fit tightly against the motor mount would be to shave the upper crosstie enough that the upper width is *less* than the specified 32".

What am I missing here?

I had to shim both top and bottom a bit. I think its just variations in all the different components coming together. Check with Kerry but I think you are within specs.

I've heard of lots of people needing several shims, with .025 and .032 sizes being used but you can go thicker if needed. I can't remember how thick is allowed but I remember some people going .090 or higher total thickness.

And yes, it's normal for the upper and lower shims to be different thicknesses.

MichaelFarley56 wrote:I've heard of lots of people needing several shims, with .025 and .032 sizes being used but you can go thicker if needed. I can't remember how thick is allowed but I remember some people going .090 or higher total thickness.

And yes, it's normal for the upper and lower shims to be different thicknesses.

Yeah, I'm talking I'd need 1/8" or 3/16" thick shims! I just checked the mount, and the distance between the upper mounts are about 1/8" less than specified in the plans. I e-mailed Sonex, we'll see what they say.

I guess it's my week for weird problems. :(

Yea, i got the 32" dimension dead-nuts on and i probably have about a 1/8th total gap. My guess is the precision of the motor mounts aren't very high. I wouldn't deviate from the 32" dimension, as this will mess with the fit of your firewall and cause a nasty chain reaction of nothing fitting correctly

Here's a pic of mine. While the pic shows four shims, I did end up doubling up a couple. I used all kinds of different metal thicknesses. The largest combination may have been near 1/8 inch.

Sorry to hear about your trouble, Andy.

I do have your solid rivets next time we meet...

Kip

N111YX wrote:Here's a pic of mine. While the pic shows four shims, I did end up doubling up a couple. I used all kinds of different metal thicknesses. The largest combonation may have been near 1/8 inch.

Sorry to hear about your trouble, Andy.

I do have your solid rivets next time we meet...

Kip

Thanks Kip! If you guys are getting near 1/8" shims, maybe I'm not as for off as I think.

If you're going to be around over the long weekend, maybe we can get together. Did you get your rivet gun back as well?

Andy, I may be flying around on Sunday. No rivet gun yet but maybe within a week or so...

N111YX wrote:Andy, I may be flying around on Sunday. No rivet gun yet but maybe within a week or so...

Cool, give me a call if you have the time and inclination to get together.

Kerry says that the welding process is not perfect, hence the small variation from plans. He thinks big fat shims is the answer, and seemed to indicate there is no upper limit to the thickness of the shims you can use.