Use of a thrust bearing on prop shaft question - Why?

[MikeP323]

Normally I just leave a 3/16" space between the drive dog and the end of the stinger on most of my boats for shaft wind up. I only use .187 shafts. My question is if I put a thrust bearing in place there do I still need to leave that much space or any space or ? I realize the shaft is still going to contract under load but if a bearing is not making contact on both of its faces then why bother with it. What say you ?

[dasboata]

Normally I just leave a 3/16" space between the drive dog and the end of the stinger on most of my boats for shaft wind up. I only use .187 shafts. My question is if I put a thrust bearing in place there do I still need to leave that much space or any space or ? I realize the shaft is still going to contract under load but if a bearing is not making contact on both of its faces then why bother with it. What say you ?

a thrust bearing really is the way to go , all the forward thrust load now is put on the motors bearing,,,,, eventually that load is going to hurt

[1coopgt]

Sorry is there any good info out there about this? The reason I ask is RTR's don't come with thrust bearings. . On all of my Cats I space the drive dog the dia of my flex shafts. 2 of my cats have wire drives so I have the drive dogs spaced about 1/16".

If you use thrust bearings is there a rule of thumb as to how much spacing you should have between the drive dog and the thrust bearing? Just what is the trust bearing doing. If the drive dog doesn't hit it it's not doing anything other than adding a little weight granted its negligible.

I'm slowly building a 1/8th scale hydro and I'll be using a wire drive . Do I need a thrust bearing on this ?

[ezhitz]

I use a thrust bearing between the collet and motor to take load off the motor bearings and just leave the gap between the drive dog and strut.Not saying that’s the best way but was told that when I first started running electric. I think if you where to use the thrust bearing between the drive dog and strut you just be guessing the amount of shrinkage in the flex. If left to much space the bearing won’t make contact to little might cause more load on the motor increasing amp load. Just something to think about.

[NativePaul]

Only use a thrust bearing at the prop end if you use a wire drive or a flex with a square drive.

If you have a regular flex there needs to be a gap at the prop end, if you use one the thrust bearing goes at the motor end.

[MikeP323]

Das Boata - Native Paul - Thank You for your input - makes sense then to put the bearing between the collet and the motor as EZHITZ says in his reply. Thank you all ALL for your ideas on this.