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Author Topic:   Spun propellor hub

msullivan006 posted 03-12-2003 08:58 PM ET (US)
This is a new topic for me, as I have spent too many years with only small outboards and big sailboats to experience it. However, my "new" '93 OR 17 with its '93 100hp Johnson seemed to exhibit the very beginnings of the problem, as I have been led to understand it on this forum ie: a sort of slipping clutch feel if power is applied too aggressively, but it goes away with just a little backing off of throttle. This is based on only the three outings I have had so far, but is something on my list for early diagnosis this spring. My real question is for some background on what causes this condition in the usual case. Is it more from aging of the rubber hub components, or usually a result of lots of use? The prop in question is an aluminum item that apears to be original (haven't pulled it yet to see what it may say inside) and in pretty good shape. What I am most interested in is whether a slightly spun hub would be an indication of heavy use over ten years? Everything I can read from the condition and the past history of my new baby is that it has been very lightly used, all in Michigan fresh waater, and I am curious if the gurus here would say that this is a contrary indicator (assuming it really is a hub issue). The boat was kept in a slip full time each season, so unfortunately it isn't the complete trailered garage queen, and perhaps the long exposure to water has a bearing as well? Thanks for all insight,
Mike
jimh posted 03-12-2003 09:36 PM ET (US)
To diagnose a "spun hub" condition on the propeller, you'll have to remove the propeller from the prop shaft. (This is a good idea to do once a year, anyway, before the prop and shaft corrode into one piece of metal.) Typically there will be a splined thrust washer on the shaft between the propeller and the engine.
The splines on the thrust washer will ensure that it rotates in unison with the propeller shaft. If the propeller hub has been spun, the portions in contact with the thrust washer will have circular scratches. A spun hub can be repaired for less than $50, typically.
A spun hub is probably more an indication of the rubber portions of the hub shrinking slightly than anything else. If the rubber tires on your car were ten years old, they would not be in "new" condition, and neither will the rubber in the propeller hub.
When you reinstall the propeller on the shaft, apply a light coating of marine grease to the shaft so that corrosion does not occur.
lhg posted 03-13-2003 03:10 PM ET (US)
For Mercury props with Flo Torque II hubs, introduced about 7 years ago, spun hubs are a thing of the past. These props no longer use the rubber hub design, but instead a splined plastic insert, easily replaceable by the consumer and simple to check. Unless an obstacle has been encountered and the plastic therefore sheared, the "spinning" problem should not happen.
I had a rubber hub let go on my older style Mercury props, and it happened without warning, no obstacle ever being hit. It happened in-shore, where the other engine easily got me home, but I was unnerved by it.
It is something that can strand you without warning, and offshore, this could be real serious. Incidentally, getting a spun off the prop shaft is difficult, since you can't block the prop to release the nut. It will spin and turn the engine over! The only way to do it to wedge somthing into the teeth on the flywheel. As I said, this is not good when you're stranded on the water.
You might want to consider getting one of these latest technology "2 part" props. For the very reason of the separate, interchangeable hub design, Mercury makes a hub kit for any brand of engine. A spare plastic splined hub can easily be carried also. The props are available in aluminum or SS. Mercury has evidently recently licensed this product to Michigan Wheel, but only for their aluminum props. Without these rights, Michigan wheel would have been hurt in their aftermarket replacement aluminum prop market. But Mercury is not letting them have it for the SS props.
Since these SS performance props are getting so expensive these days, having the interchangeble hub design greatly enhances their re-saleability on the secondary market, such as here or E-bay. It also saves money if one repowers to a different brand. Any brand engine owner can buy the prop, and only needs a $30 hub to use it on his engine.
msullivan006 posted 03-14-2003 08:46 AM ET (US)
Thanks for the tips on what to look for. I'm going to pull it this weekend, after yesterday's coating of fresh snow melts ;-) It was 10 degrees at the house this morning, but "they" promise close to 50 over the wekend.

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Author	Topic: Spun propellor hub
msullivan006	posted 03-12-2003 08:58 PM ET (US) This is a new topic for me, as I have spent too many years with only small outboards and big sailboats to experience it. However, my "new" '93 OR 17 with its '93 100hp Johnson seemed to exhibit the very beginnings of the problem, as I have been led to understand it on this forum ie: a sort of slipping clutch feel if power is applied too aggressively, but it goes away with just a little backing off of throttle. This is based on only the three outings I have had so far, but is something on my list for early diagnosis this spring. My real question is for some background on what causes this condition in the usual case. Is it more from aging of the rubber hub components, or usually a result of lots of use? The prop in question is an aluminum item that apears to be original (haven't pulled it yet to see what it may say inside) and in pretty good shape. What I am most interested in is whether a slightly spun hub would be an indication of heavy use over ten years? Everything I can read from the condition and the past history of my new baby is that it has been very lightly used, all in Michigan fresh waater, and I am curious if the gurus here would say that this is a contrary indicator (assuming it really is a hub issue). The boat was kept in a slip full time each season, so unfortunately it isn't the complete trailered garage queen, and perhaps the long exposure to water has a bearing as well? Thanks for all insight, Mike
jimh	posted 03-12-2003 09:36 PM ET (US) To diagnose a "spun hub" condition on the propeller, you'll have to remove the propeller from the prop shaft. (This is a good idea to do once a year, anyway, before the prop and shaft corrode into one piece of metal.) Typically there will be a splined thrust washer on the shaft between the propeller and the engine. The splines on the thrust washer will ensure that it rotates in unison with the propeller shaft. If the propeller hub has been spun, the portions in contact with the thrust washer will have circular scratches. A spun hub can be repaired for less than $50, typically. A spun hub is probably more an indication of the rubber portions of the hub shrinking slightly than anything else. If the rubber tires on your car were ten years old, they would not be in "new" condition, and neither will the rubber in the propeller hub. When you reinstall the propeller on the shaft, apply a light coating of marine grease to the shaft so that corrosion does not occur.
lhg	posted 03-13-2003 03:10 PM ET (US) For Mercury props with Flo Torque II hubs, introduced about 7 years ago, spun hubs are a thing of the past. These props no longer use the rubber hub design, but instead a splined plastic insert, easily replaceable by the consumer and simple to check. Unless an obstacle has been encountered and the plastic therefore sheared, the "spinning" problem should not happen. I had a rubber hub let go on my older style Mercury props, and it happened without warning, no obstacle ever being hit. It happened in-shore, where the other engine easily got me home, but I was unnerved by it. It is something that can strand you without warning, and offshore, this could be real serious. Incidentally, getting a spun off the prop shaft is difficult, since you can't block the prop to release the nut. It will spin and turn the engine over! The only way to do it to wedge somthing into the teeth on the flywheel. As I said, this is not good when you're stranded on the water. You might want to consider getting one of these latest technology "2 part" props. For the very reason of the separate, interchangeable hub design, Mercury makes a hub kit for any brand of engine. A spare plastic splined hub can easily be carried also. The props are available in aluminum or SS. Mercury has evidently recently licensed this product to Michigan Wheel, but only for their aluminum props. Without these rights, Michigan wheel would have been hurt in their aftermarket replacement aluminum prop market. But Mercury is not letting them have it for the SS props. Since these SS performance props are getting so expensive these days, having the interchangeble hub design greatly enhances their re-saleability on the secondary market, such as here or E-bay. It also saves money if one repowers to a different brand. Any brand engine owner can buy the prop, and only needs a $30 hub to use it on his engine.
msullivan006	posted 03-14-2003 08:46 AM ET (US) Thanks for the tips on what to look for. I'm going to pull it this weekend, after yesterday's coating of fresh snow melts ;-) It was 10 degrees at the house this morning, but "they" promise close to 50 over the wekend.