thrust bearing installation

[Basstronics]

Depends on bearings.

If its a radial ball bearing it will only take a small amount of thrust. If its angular it can take some more. However thrust loads are not what they were designed for.

A thrust bearing in larger applications is a good idea. There is no real con against using one... The added weight or rotating mass is negligible.

I know a few things about bearings. My last machine I was Project Engineer on I utilized a 126" thrust bearing special made in Thailand. I also utilized a ton of tapered roller bearings in spindles as it was a tube mill.

[stumblinh]

Wow, lots of bad information in this thread....

A thrust bearing does nothing if it does not transfer thrust from the prop to the hull. It does this ONLY if the bearing is pinched between the coupler and the motor under forward movement - otherwise the motor's endbell bearing is transferring all the thrust (usually not a bad thing at all). When set up correctly a thrust bearing will not be loaded when the motor isn't running, otherwise it will cause unwanted friction. If a motor shaft has axial run out - end play - measure the play and install the thrust bearing so that only half the end play remains. This will insure two things - that the bearing is actually taking thrust when the boat is moving, and that the thrust bearing is not adding friction by pinching the PTO bearing between the internal shims and the thrust bearing/coupler.

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You said nearly the same thing.. when there is no load you don't want a load on the thrust bearing.. otherwise it will cause unwanted friction :P If you have as much "play" as you are describing in your comment, I suggest re-shimming the motor, a lot of bad things can happen if you have too much play.

[ray schrauwen]

Gave up on thrust bearings when I went to Neu & Leo/ TP power motors. Never had a need. Tried one on a 1521 1.5 in df33 4s2p and could never get it shimmed right, loud as hell. Removed it and it ragn like a dream with less heat. To each their own though.

[Mike Caruso]

I was running my motor out of the boat and it made a small amount of temp.

All electric motors build heat when run without a load because virtually all the energy goes into heat, not torque. The thrust bearing had nothing to do with heat buildup in the motor.

This is the whole story.
Correct they all make heat, but what I was saying is MY MOTOR made less heat with the thrust bearing installed. I don't know why this motor is pulling so hard to one end plate? What I do know is lower motor temp is a good thing. I just got back from running today and I removed the 45 x 68 which ran 45 mph and installed the stock prop. No data logging today (forgot laptop) but it looks fast and sounds like higher rpm. This boat drives and runs just great, you can carve the water up with it... so cool!

Since the 70's running speed-o cable drive lines many people used the engine ball bearings for the boats thrust. Some used a propeller thrust bearing to take the load off the engines crankshaft bearings Engineering wise ...ball bearings are not designed to act as thrust bearings you are correct 100%. But they have been and still are being used that way in our boats. If they work and don't fail all the better for us.
Lets go boating