I was wondering what procedure everyone uses for tightening down the Wacker Engines prop adapter to their flywheels of their engines?Seeing as there is no flat anywhere on the prop adapter,I can see only one way of gripping this thing and getting it to tighten down enough so it doesn't accidentally throw it and spin off in flight.I was thinking of using one of those adjustable rubber strap type wrenches to grip it and tighten it down with.Is there a better way than this and is it a good idea to use Loctite on the crank shaft prior to tightening down the prop adapter?If so,which strength of Loctite is sufficient,red or blue?

I bought a Sears strap wrench. I also used Loc Tite.

Enjoy,

Jim

The procedure we use here at GCBM R/C Models Inc. is this: First, yes, a rubber strap wrench works really well. We coat the key slot and the taper on the crankshaft with JB Weld. We then put the flywheel on (assuming you are using a flywheel). Next, we coat the threads with JB weld and tighten the prop shaft with the strap wrench. Very secure bond.
Regards,
GPB

Mike,
How hard is it to disassemble if needed?

Dave

Hi Dave,
Well, the idea is to be permanent, but this is due to liability concerns for the very question this thread asked. I have removed prop shafts attached with JB Weld by heating with a blow torch, but it was twisted off with a pair of vice grips and a lot of arm strength. The machined prop shaft, though useable afterwards, was really scared up.
Regards,
Mike

Hi Mike,
That makes sense. Thanks, Dave

You can drill a hole in it to insert a piece of large music wire in to tighten it, or make a wrench with a steel rod that fits in the hole and the wrench touches 180degrees from the hole. Steve

Or, one way to make it without welding, use a piece of tubing that slides over the adapter, cut it longer than the adapter, drill the same size hole as the hole in the adapter for a pin, then drill a larger hole in the other end of it for a drive rod to fit through. SS

Guys, If you put a prop on it, don't you have a built in handle to tighten it with? It won't work taking it off. With a 20" prop, that allows a good bit of leverage on one side. I loctite mine, but have only used prop and arm strength to tighten it. The only time I had to remove one, I had to drill a hole in it, so I guess it was on pretty well.

Well, a couple of things. One, I personally would be really pissed if I bought a motor and found the flywheel/prop adaptor assembly had been JB welded together!! Just my opinion, but it seems like a huge amount of overkill, unnecessary, and makes for a nasty hassle if/when you go to work on the engine!

Secondly, why not carefully file a couple of flats on the adaptor until you have a nice tight fit for a wrench? Then assemble it with a little Loctite. If you are lucky enough to have a mill, or know someone that does, you could do the flats that way as well.

AV8TOR

Yes, overkill is necessary when liability is an issue, and that's not an opinion, that's a fact. Unless the crankshaft gets bent, there is really no reason to remove the prop shaft. Disassembly voids our warranty anyway.

Mike,is there not a concern here with the blow torch and heating the area up too much?I think I'd be afraid of over heating the crank shaft too much possibly and taking the temper out of the steel.This could possibly weaken the crank and allow it to get bent much more easier in a mishap.I know where your coming from with the liability issue and it seems like there's always somebody out more than willing to sue your a** off and it's always YOUR fault.Like Av8tor was saying though,that would be one bear of a job getting that sucker off if I had to.Especially after after the warranty runs out.Great input guy's.Thanks a million!

You would have to get it really hot to damage the crank. You would want to concentrate the heat carefully on the mag hub, not the crankshaft. I would be more worried about ruining the rubber crank seals.

I am trying so hard not to jump in here and complain about liability..... The gov. is all too happy and willing to control every aspect of our lives; why can't they solve this horrible, debilitating liability problem??

AV8TOR

Tubrobeaver, you make a very good point here. On the rare ocassions an engine comes back for repair with a bent crank, we usually just throw the bottom casing in the garbage, including the crank, flywheel, and prop shaft, and bolt a whole new assembly of the same onto the piston and jug. Fast, simple, and costs the customer a nominal amount. We went to JB Weld three years ago when the soft, "cast-in-the-flywheel" woodruff keys were shearing if someone had a hard enough prop strike. This solved the key shearing issue, and provided a more secure screw joint with the shaft and the crankshaft. I am personally of the belief that as long as the crank is straight and the flywheel is in the correct position, there is never a reason to take the prop shaft off.
Regards,
Mike