I am currently trying to put together a Superstar 40 ARF kit and the engine mount that came with it is one of those break-away mounts and it uses phillip head screws. I don't feel comfortable with this type of mount. Should I replace with a fixed mount or change the phillip head screws with hex bolts? My main concern is vibration loosening the bolts holding the engine.

If the Philip head screws you refer to are wood or sheetmetal screws (No nuts), and if the break-away mount you speak of is one of those 1/4" plywood types, I would ditch them and use something you can but a nut on.

I agree.
Go get a 'normal' glass filled nylon mount, drill holes all the way through it and fasten the engine with one of the following methods:


1. Bolt + lock nut (lock nut has a nylon rim and you should NOT use lochtite or any thread locking compond on them)
2. Bolt + 2 nuts, the second nut secures the first nut. (use threadlock compond on both nuts)

I use method number two and it works perfect!



[link=http://www2.towerhobbies.com/cgi-bin/WTI0095P?FVSEARCH=engine+mount&FVPROFIL=++]Tower Hobbies engine mounts[/link]

Yup, the break away mounts have a habit of rotting from fuel soaking them and breaking when they shouldn't. If you use it, make a few extras and coat them with balsarite or clear dope. Otherwise, ditch them and use glass.

Everyone is right including Flyboy's comment about fuel soaking. But I think a break-away mount is a good idea because it helps absorb energy and cause less damage.

The reason the mounts get fuel soaked is simply because they aren't fuel-proofed properly. Some of them have no fuel proofing at all and others get fuel proofed before the holes are drilled.

Finish the mount completely including all holes. Then drop the mount in a can of clear poly for an hour letting it soak. Shake the can occassionally. Pull it out and stick a wire through one of the holes and let it drip dry. I use a paper towel to soak some of the puddle off at the bottom after it stops dripping because some of the poly pools there.

Anyway, it's simple and it works.

Also, I recommend using stainless steel hardware around the engine. It holds up better. Allen heads are best because you can use a ball-driver to get at it when you don't have a straight shot which is common around the engine. Use a regular allen wrench to tighten down the bolts though. A ball driver can't handle a lot of torque unless you buy expensive hardened drivers.

Is this a wooden mount, or an aluminum mount? Hobbico likes the aluminum casting "one size fits all" type -- and they sure can break in a hard prang.

you also want to use allen heads because phillips will strip if they are locked in or if you use the wrong size screw driver. so far i have never been able to strip an allenhead any bigger than 1/16"

I guess I should've said it's an aluminum engine mount with 2 metal plates that get screwed down to hold the engine by it's flange.

Aha -- the old Hobbico "one-size-fits-all" breakable engine mount. Get a GP adjustable composite mount.