Chafing on Upper Left Motor Mount

During annual condition inspection, on the upper left side, I found chafing between the large, powder coated, forward washer and the motor mount. It had worn away the powder coating over an area about 1/2 inch long. Even after loosening the nut all the way, the interference prevented the washer from being rotated.


I relieved the interference by grinding and polishing, then painting for corrosion resistance.



Both of the washers on the bottom mounts are very close to the motor mount frames, but the engine sag tends to push them away from the members instead of chafing.

Thanks

Thanks for the heads up. I will make my own note to check. Please be sure to pass on to Van's.

Pete

Good catch!

Dave

Easy to check mine, my cowling is off.
Upper Left (pilot side), 1/8 inch clearance
Upper Right - not close
Lower Left - 1/8 inch clearance
Lower Right - A piece of paper just fits there. I might grind that one a bit in place at another spot on the washer, (there is access room to do that), loosen the bolt, and turn the washer.

I had problems with two washers; upper left and bottom right.

Good catch. I am doing my condition inspection and will report what I find when I take a second look.

I noticed it was close when I built the plane so I ground off some of the washer when I assembled it.


Brad Stiefvater

Gary, checked mine today, and I have 1/8 to 3/16 space on mine. I don't want to ask a dumb question, but did you fully torque the bolt to ensure the rubber mount was fully seated? if you did so I suspect you could have a mount that may be a fabrication problem with the fitup of components at welding. I experienced that when fitting a new mount on my 6A about 5 yrs ago. The welding fitup was far enough off that I had to remake the entire front cowl. What I was told by Vans at the time was the weldments were not tightly controlled regarding the component fit as the cowl was made to fit the mount as it is during new conmstruction. The problem with that was new mounts don't fit existing cowls. I was under the impression they were going to attend to that and they probably did. You just may have received one that is really off the aim. Clearly you should not have to modify anything significant on the 12 to make it fit. Perhaps you should ask Vans about it as they should know of such issues.
Dick Seiders

Thanks for the heads up. 100 hours on the rv12 and the top left engine mount washer had worn some of the powder coating away - too close for comfort!

My upper left was fine, but the lower right needed a little relief when I installed it. There is a relief ground into the washer so I must have noticed it when I assembled it.

Thanks for the heads up.

I forgot to mention in the first post, N523GT has 57 hours TT.

Dick, I torqued the bolts per instructions, 160 to 190. I don't remember what it looked like when I installed it, but I'm sure that the upper left changed over time. It was making full contact with the tubing and the pressure from the washer made the bolt difficult to remove.

I'm in the middle of building a tube and fabric kit, and it seems that precision is more difficult with welded structures. Some parts need persuasion to make them fit. Must be all the heating and cooling of the steel?

Attention to torque. I installed the engine and i misaligned the bolt below and the ENGINE MOUNT BUSHING is not even with the MALE ISOLATOR i have put it in with the vise

Daniel Switzerland

Gary, I don't know about the heating and cooling on the welded mount, but it should fit without modification. I appreciate fact you would not be inclined to ask for a new mount and have to pull the engine to install it. My hope is that someone from Vans reads all this stuff, and will look into the fabrication of the mounts to save others the fit problem. That is the real value of this forum as we provide this huge test bench for good data to the manufacturer.
Dick Seiders

Little tips like this one, remind me to donate yearly to this website!! Thanks all, keep the tips coming. Will be doing my 2nd conditional inspection in October. Way too cold to do it in November when due. (Petie Anderson in TX is laughing!).