I'm installing a new engine mount on my Ultra Stick 40 ARF this afternoon. The Dave Brown engine mount directions say to put a drop of oil on the sheet metal screws when bolting the engine to the mount. Will they back out if oil is on them? Should I pre-drill the holes first? The directions don't say.

Thanks,
Joe

You should definitely pre-drill the hole first. I doubt if you could screw a sheet metal screw into the mount without breaking off the head if you didn't! It's also true a drop of oil will allow you to screw it in easier, but I would have thought it also lets it unscrew easier too!

For what it's worth, (and I expect this is a controversial statement) I went through a phase of using screws as opposed to nuts and bolts, saying to everybody who would listen that it's a better solution, but, since the screw gets looser and looser with age and wear, I have now returned to locking nuts and bolts and have had no problems since.

-David C.

Thanks for the help Dave. I prefer to use locknuts also but the bottom of this mount is not flat so there is no edge for the locknuts to rest against. I would MUCH rather put locknuts on it.

Joe

I agree that's a problem. I tend to push the bolts up from the bottom, that is, the nuts are on the top of the engine mounting lugs. This tends to make the bolt bend slightly just under the heads, but gives a good surface for the nuts to sit flat. It seems to work OK (so far!).

-David C.

How about if I use the sheet metal screws and instead of oil use a drop of blue lock-tite? That would make it go in easier and stay in. Will it react with the glass in a bad way? Will I be able to get the screws out again?

I'll propably go with the sheet metal screws and keep my eye on them.

Joe

When I was using screws I used blue locktite and it seemed to work pretty well, and the screws could be removed if needed.

Yes, my experience has been if you keep an eye on the screws, and check for tightness it works fine. The one advantage it does have is that there is still friction against undoing completely when the screws are loose.

-Dvid C.

Cool. I'll use the screws and the blue lock-tite. I appreciate the help.

Joe

I have one of those Dave Brown mount that you mentioned. My experience is that without first drilling a through hole (of a smaller diameter than the screws), it is extremely tough to put the screw through. The mount is glass-filled and it is extremely hard. Unlike soft woods, wood screw could be easily tapped into the wood without much problem.

Now, I faced a problem, with the supplied screws with Dave Brown mounts, I couldn't get the screws to sit perfectly on the mount. I really suspect that at least one of the 4 screws does not have a good clamping force on the mount. I have tried using electric screw driver of high torque but a few attempts show that I may risk damaging the recess of the screw head, damaging the screw completely, while the screws seems stuck at the mount.

I would try a 2nd attempt to use bolt and nuts instead with a new mount of course.

Right or wrong this is what I have done with the Few Dave brown mounts I’ve used. After locating the holes for the motor I drill the holes all the way through, now I mount the motor (out of the plane) one screw at a time using a file to make a small perpendicular shelf/flat spot for the nut and washer to rest against on the bottom side of the mount. It’s kind of a pain in the arse but it worked for me.


John