Flex shaft myth?

[SweetZ28]

Can't you just put a thrust type ball bearing right before the prop so all pressure rides on the bearing .... and how long would a thrust bearing last run under water?

2 of my boats use plastic washers on my widow maker i run a gap because of it's set up.
But on my brushless 550 fighter i have the washer with hardly any gap at all.
On my apache 24 brushless i have a thrust bearing at the motor.... So this is why i wonder will a thrust bearing last and work good right before the prop?

[sundog]

Many people on this forum have issues resolved with this one bit of advice of leaving a little gap. It may not be correct in leaving a little gap, but issues have been resolved in doing so. People offer advice here typically because they already went through the pains and expense so you don't have to.

This is what I am getting at. If the torque is to be on the strut and not the motor/mount then a square ended cable that slides into the prop shaft will allow the flex to shrink if need be, while keeping all the torque on the strut/thrust bearing where it belongs. Leaving 'a little gap' is a turkey shoot - how much gap? Too little and thrust is on strut washer & binding occurs. Too much gap and the torque goes through the cable to the motor. Yes, you can run the same setup over and again to find that perfect gap (if nothing ever changes) and be happy. Or use a square ended cable/prop shaft and be done with it. I know it's not very popular because you'll need to remove the strut to lube the cable, but in my opinion it's the best way.

Or go to Mini's and Micro's where little (if any) flex shrinkage occurs!

[Punisher 67]

This is what I am getting at. If the torque is to be on the strut and not the motor/mount then a square ended cable that slides into the prop shaft will allow the flex to shrink if need be, while keeping all the torque on the strut/thrust bearing where it belongs. Leaving 'a little gap' is a turkey shoot - how much gap? Too little and thrust is on strut washer & binding occurs. Too much gap and the torque goes through the cable to the motor. Yes, you can run the same setup over and again to find that perfect gap (if nothing ever changes) and be happy. Or use a square ended cable/prop shaft and be done with it. I know it's not very popular because you'll need to remove the strut to lube the cable, but in my opinion it's the best way.

Or go to Mini's and Micro's where little (if any) flex shrinkage occurs!

That is the setup I use with absolutely great success

[ray schrauwen]

How do you get the strut back correct?

[sundog]

I think you mean "after you remove it (for servicing) how do you make sure it's installed at the original angle". That is a good question. I would think that if you set the boat on a flat surface you could measure to the strut. Or better yet, make a jig (wedge) to slide under it might be easier/faster. But that's just speculation - anyone got experience with this?

[keithbradley]

I think you mean "after you remove it (for servicing) how do you make sure it's installed at the original angle". That is a good question. I would think that if you set the boat on a flat surface you could measure to the strut. Or better yet, make a jig (wedge) to slide under it might be easier/faster. But that's just speculation - anyone got experience with this?

To grease the shaft you can leave it in the coupler and just remove the motor and shaft together...depending how easy that is in your setup.

[H2OCamel]

It is my understanding that squared end flex cables fit into square drives on the motor end? the prop shaft end is still round and gets soldered in to the drive shaft? I have never seen one in person. Is this what you are using? It makes sense that the flex could expand and shrink freely moving in the drive coupler on the motor. But how do you keep from losing your prop? A locking collar around the flex cable? Can someone post pictures? I have always left a small gap in my flex shafts.

Interesting reading I always love learning more! Thanks for all the sharing of experiences.

[keithbradley]

It is my understanding that squared end flex cables fit into square drives on the motor end? the prop shaft end is still round and gets soldered in to the drive shaft? I have never seen one in person. Is this what you are using? It makes sense that the flex could expand and shrink freely moving in the drive coupler on the motor. But how do you keep from losing your prop? A locking collar around the flex cable? Can someone post pictures? I have always left a small gap in my flex shafts.

Interesting reading I always love learning more! Thanks for all the sharing of experiences.

The ones I have are normal on the motor end, but square on the other. There is then a prop shaft with a square drive on it that never gets bonded in any way to the flex. It is driven by the square end of the flex cable.

[keithbradley]

http://fightercatracing.com/index.php?page=shop.product_details&flypage=flypage.tpl&product_id=54&category_id=24&option=com_virtuemart&Itemid=1

[Punisher 67]

How do you get the strut back correct?

The nuts are fiberglass resined in on the other side of the rear . Its is impossible to screw anything up . there is no adjustment and the strut only fits it one way in the exact same spot every time