Propeller strut sealing

[Howard]

Correct osprey21 :-)

I'm not even sure what those guys are talking about. I just wanted to share my idea about a proboat I have. I wasn't asking for an explanation of everyone's theories about qua-tom physics And I wasn't saying NOT to grease the shaft often. I WAS JUST SHOWING A WAY TO MAKE A FILLER PLUG to unscrew and keep the grease in. I don't know of any boat, airplane or car with a rear, transmission or engine that has an open hole anywhere that will allow fluid out.

[lenny]

Thanks for the heads up that its a square drive setup,

Now it makes sense to me,lol

But yes, Rears, Transmissions , Engines, Have vents in them to relieve pressure or they blow seals out.

[keithbradley]

Please don't get me wrong but do you realize how much the flex shortens on high load??? A thrust washer will bind and you will blow your esc in seconds.... Unless of course your running small props low pitch on low rpm.. Eg zero or no load... Go see the back of a saw boat.. You'll understand.

I have some pretty fast boats tiny, so I don't really need to look at anyone else's. I understand what you're saying but I think you're just not familiar with the setup on Howard's boat. The flex is allowed to shorten without binding the drive dog against the back of the stinger/strut.

[pescador]

I had a square drive on an older nitro boat and the flex just floated in the collet to allow for contraction.
It was supposed to be easier on the engine bearings because the stress is at the strut.

[jasoncyclone]

A square drive or full floating flex does not require spacing between the drivedog and the strut, just needs a washer, but a full length flex with stubshaft does require a spacing.

[ice_spy]

Is there a cut off point for higher rpm set ups to require the strenght and trueness of a 1piece shaft from a floating square drive flex? And does a wire drive set up grow or shrink under high rpm, also requiring a drive dog to washer spacing?

[Jeff Wohlt]

No matter if you have a square drive or not the prop thrust will always push against the end of the stinger which just increasesrotational load on the motor. When you take the load at the motor...WITH a thrust bearing you are then reducing your load for the motor to rotate easier. I have never seen the benefit of a 2 piece unit like that...except they WILL round the shaft off eventually or may quickly depending on props in and out of the water. I have sold tons of new flexes that people said the square ends will not hold up. Also they are not easier to service. I also wwipe my wires or flexes down each run and grease them. Just something I do to makes sure that driveline is as good as can be for each run. Just my 2cents...worth about 1...LOL

[Jeff Wohlt]

You still leave the gap on wire...when you put the stuffing tube bend in rightplace (just the J up thru the hull) the push of the prop will actually give you clearance at the bend and gives you a much free-er (good word) running drive system.

[Boaterguy]

Jeff, you being the wire master, how big should the gap on an 078 be? the wire is ~12 inches (oh yeah and the drive cable is also that long )

[crrcboatz]

I respectfully disagree with both points u made. First the mixture of water/grease that develops actually breaks down the viscosity and thickness of the grease and it passes out harmlessly around the rear of the strut around the bearing/stub shaft fitting. No 2 I have run rc boats since 1978 and never once not once had a cable fail me. I DO NOT remove it after each run and re lube. Rather, i hand rub each cable using a drill mounted in my vise with the speed locked in and the flex cable on the business end. I grease up the shaft and with a greased rag, plug in the drill and run the rag up and down the shaft for about 1 minute. This works the grease deep into the flex shaft. I store them in ziplock bags greased. On run day I simply install them as is run them all afternoon, and NEVER have lost a flex shaft.

Personally I like this idea of the thread and seal tip and plan to try it.

There are several reasons for that hole you decided to plug up. First one,........as heat or friction occurs the grease is allowed to expand and push out thru the paths of least resistance. Thats normal. Grease (oil suspended in a gelatanous media) is what provides lubrication. Blocking its exit path does not make a better lubrication system. Water and grease will mix. Its an accepted part of driveline operation.
Second one,.....You should be taking your flex assy apart after every run. Then clean and regrease. Not on the second or third. Its part of a maintenance plan you should adhere to and ensure happens every time. Other wise you will break drive lines due to mechanical failures. Lose a couple $30 or $50 props and it will become engrained. Comes with experience.

John