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Engine mount to firewall not flush

G

goanddo

Member
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Has anyone else seen this issue? This engine mount does not sit flush to the firewall. The bolt is torqued to 190 in/lbs. And yet still, HALF of the way around the bolt there is this gap of .004 of an inch and no gap the other half of the way around the bolt. The quick build firewall is not perfectly straight and flat. Prior people have written about a gap, but not a gap only halfway around.

I am so grateful for any thoughts anyone can share. Thank you.
 
I would bet that Vans would tell you to put away the feeler gauge and build-on. That is what I would do.
 
If you removed the mount I think you would find that the bushing that the bolt passes through is not flush with the mount tabs Torque to specs and build on!
 
Thanks Ron!

Thanks Ron! Another thing I need to check on mine. :)

Now that I think about it, what is the function of that disc/flange? Distribute the load? Look nice? I've seen aircraft with engine mounts without that flange, and they seem to be flying ok.
 
Get out your belt sander, Dremel, or surface grinder (if your shop is so equipped) and make the dang thing fit the way you want it to fit. Or make a suitable shim(s).

Then build on!
 
JB Weld

JB Weld if you really want to fill the void :)

But surely 1/2 of the washer area should be plenty.

3G negative max, compared to +6G on the lower mount points.

Finn
 
Thank you!!!!

Thank you!!! The collective brain power of this group is fantastically enormous!!! I truly appreciate your help. Thank you!
 
My original engine mount was so bad on my 14a that I had to use a wrench and screw the 6th bolt into place. The first 5 slid easily into place. At first I had no idea what the heck was wrong, then I put it on a granite counter top and one of the mounting brackets was way off. I posted this a while back:

http://www.vansairforce.com/community/showthread.php?t=163364&highlight=engine+mount

I sent pictures Vans and they replaced the engine mount. If you want to see the pictures, I just posted them on my facebook page (Ken's RV-14: https://www.facebook.com/Kens-RV14-632288410496405/).

I am not sure how bad it has to be for the mount to be replaced, but I would consider removing and putting on a flat surface to see how bad it really is before you torque down the bolts. Do you really want that kind of constant torque on the bracket?
 
Yeah 0.004 isn?t very much. I would just take a file to it and file a little bit off the lower side. If you inspect the mount closer it may just be a small spot. Also make sure the mount ant the firewall are both deburred.
 
rapid_ascent said:
Yeah 0.004 isn?t very much. I would just take a file to it and file a little bit off the lower side. If you inspect the mount closer it may just be a small spot. Also make sure the mount ant the firewall are both deburred.
Click to expand...

The problem with filing down the mount is that you may end up with that "leg" not even touching the firewall at all. Once you start modifying the mount you own it!

-Marc
 
The question is: What is the gap in the resting state--not torqued?

I bet the gap when sitting on a flush surface is much more. Thus there could be a lot of stress on the joint since the gap closes upon tightening.
 
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