thrust bearing.....what's your take?

[kfxguy]

So I did some searching of course first. Found a little info but it was a few years old. Times have changed. I was thinking about a thrust bearing at the strut and at the motor....I mean Two is better than one right? Lol. No really, I saw a couple pics on here where the thrust bearing was at the strut, in between the drive dog and the strut. I think it would be better to have there, no? Keeps the flex from being pushed on and whipping or winding in the stuffing tube. At least that what I think is going on. Guess if you had one on the strut, the motor one is not needed. Do the make sealed ones? Or a stainless or ceramic one will work in the water just fine as long as I lube it. I just like to try new stuff. Sometimes it helps. Sometimes it doesn't. What's your take on it?

[urbs00007]

personally , I think additional bearings are just something else to fail. The drive-dog shouldn't hit the strut, even with a thrust bearing it's additional drag, and will tighten up flex cable. same thing at the motor. motor bearings take the thrust , no problem. do you have problems with your flex shafts? if you do its not from lack of thrust bearings.

[T.S.Davis]

I always run a thrust at the motor. At the nats I was short a bearing. I was told not to worry about that.

Then proceeded to blow the end bell out of a Neu.

[larryrose11]

Bummer!!!

[Cooper]

I use to use thrust bearings but for them to actually do what they are intended they need to rest against motor mount or can of motor. Easy to do by washer, but keep in mind flex shaft shrinkage. Don't want drive dog tight. But not having any way of lube and the quality of motors now I have just eliminated using them and haven't had any ill findings. Keep in mind I'm running 100mph+ two passes and in. Agreed with,above, just one more part to fail. Keep t simple and free in my opinion. :)

[iridebikes247]

wouldn't use one. I feel like it can create problems, if a motor needs a thrust bearing to run correctly, probably not the best motor.

--Have run every leopard, tp, and neu motors. I've had a few cheap bearings wear out but never did I feel a thrust bearing was the solution. Its cool to be different and have a different way of doing things, you're kinda re-engineering stuff though once you add a bearing in a place when tens of thousands of boaters haven't had an issue. Makes sense though "thinking," is the fun part of the hobby but this is a more dicey thing as things work flawlessly without the bushing. A few years ago I ran really expensive oiler units on one of my big cat projects, it was cool but just got in the way.

[Chilli]

I've never used one on a Neu motor including 95 mph SAW boats and so far so good. I did purchased a used Neu motor that was messed with by the previous owner and the end bell was not secured very well when reassembled. I trashed it!

I do use thrust bearings on my P-Limited motors though with no problems.

I just leave the standard gap (same as diameter of the prop shaft) between strut and drive dog. I let the flex do what it wants inside the stuffing tube.

[kevinpratt823]

I'm pretty sure if you see one on the strut, it's because it is a 2 piece design, where the shaft just slips over the square end of a flex shaft and is held in by a ferrule, like a lot of outboards, or I believes a stock Genesis has this setup. Otherwise when the flex shortens it will bind. I have run with and without. Lateral loads are real tough on bearings, but surprisingly I have not worn out a bearing because of it in boats.

[jcald2000]

If you take the thrust at the strut it will push the nose up. At the motor it pushes the nose down. I have never used a thrust bearing and have no bearing problems. I use 75w rearend lube once a weekend with no loss in rpm or speed for oval racing. Thanks again Jay Turner for the oil tip.

[Fluid]

The bearings in most quality motors are designed to take axial loads - think airplane use. As long as the end bell is well secured there is no technical reason to add another bearing. It is easy to add substantial drag when installing a "thrust" bearing with too much preload - or to make it worthless with too much play. The difference can just a few thousandths of an inch. I wonder how many thrust bearings are actually installed correctly?


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[martin]

As said your wasting your time with a thrust bearing at the strut if its a 1 piece flex, if the correct gap is used between the dog & strut. The dog will not contact the thrust bearing.

[kfxguy]

Good info in this thread. Guess I'll leave it alone

[runzwithsizorz]

If you take the thrust at the strut it will push the nose up. At the motor it pushes the nose down. I have never used a thrust bearing and have no bearing problems. I use 75w rearend lube once a weekend with no loss in rpm or speed for oval racing. Thanks again Jay Turner for the oil tip.

Could someone please explain to this non rocket scientist the science behind this theory? It seems to me that you are not altering thrust as much as you are altering friction? And that thrust would remain a constant?

[kevinpratt823]

Could someone please explain to this non rocket scientist the science behind this theory? It seems to me that you are not altering thrust as much as you are altering friction? And that thrust would remain a constant?

This hadn't occurred to me until I read the post because I don't have thrust bearings at the strut, but it does make sense, as you are altering the location at which the thrust is being applied. With no thrust bearings, or only one at the motor, the thrust from the prop is transferred up the flax shaft to the motor and partially the curve in the stuffing tube, pushing the boat from a more central point. With a thrust bearing at the strut 100% of the thrust/forward drive is transferred directly to the strut at the rear. Imagine you are pushing the boat with a stick at the motor, as opposed to pushing the boat from the bottom of the transom with your finger......

[flraptor07]

Could someone please explain to this non rocket scientist the science behind this theory? It seems to me that you are not altering thrust as much as you are altering friction? And that thrust would remain a constant?

Bingo, except you are altering the point at which the thrust is being applied.