Rehubbed prop issues

[heypawpaw]

Picked up two OMC 9x10 aluminum props that were rehubbed from the prop shop yesterday. Instructions were to wait until today before using and to operate at slow speed for 15 minutes before loading This afternoon after installing one of the props on 20 hp Johnson I noticed that when I turned the prop it rubs on port side of gearcase as if shaft is bent. Removed prop and rotated 180 degrees put it back on and the same area of the prop rubs same area of gearcase. After removal and inspection I measures from front of prop to brass hub where shear pin seats and the new hub is seated 1/32 " deeper on one side than other. Put other prop on motor and same thing happened rubbed in same place. Measured front of prop to hub as on other prop and this prop measures even all around. Propeller shop isn't
open again until Monday. Question: Is this normal and will running it at slow speeds will correct issues or should I just wait until Monday and return props to shop? Years ago I had a stainless prop rehubbed for 50 hp and don't remember having a slow speed break in period or any other issues. Thanks for all assistance.

 

[jimmbo]

Sounds like the huba weren't pressed in straight. Myself I wouldn't it run them in that condition. Someone will write that the hub will center itself and everything will be all right. But what if the wobble increases? Serious damage to the case where the interference is occurring could be the end result. If you really need to use the boat this weekend, go to the dealer and buy a New Prop

 

[Sea Rider]

Bad investment re hubbing a cheap alum prop, props a not just pressed, are vulcanized, there's a rubber bond between middle prop body splines and prop tube shaft splines. It's same vulcanization as engine support where 2 metal parts are bonded together.

If just pressed, with time and torque will eventually fail shortly turning good for just displacement speeds. Personally I'm not a big fan re hubbing props as the cost is just a bit less than going for a new one.

Yep, don't ruin the prop shaft housing running descentralized props rubbing inside it..

Happy Boating

 

[heypawpaw]

Thanks jimmbo and Sea Rider $18 each plus tax was less than I expected. The guy at prop shop empathized possibility of inner ring splitting while pressing in hub. He said the low speed period of operation is to let solvent in hub work it self out. That's why I questioned low speed running it as is. Should I contact prop shop to resolve issues or are you saying eat my loss and get two new props. One prop bought online for $47 in box looked new until it slipped. other prop is old and dinged up a little.

 

[Sea Rider]

How much are Solas alum 3 blade props with same diam and pitch ? Check Iboats. Buying second hand mint props could turn into Pandora props, good lookin outside, nightmare inside. Gong for new props is the best investment ever.

Happy Boating

 

[QBhoy]

Is there a thrust washer missing or nut tightened down on locking tab washer (if it has one)

 

[jimmbo]

That engine probably uses a drive pin, even if is a splined proshaft, so there is no thrust washer that you are referring to. The should be a washer that fits on the rear of the prop directly in front of the dive pin, The washer is required, in the event of a spun hub, it prevent the prop from sliding back and jamming the drive pin to where it can't be removed easily. There is no locking tab washer either, a propnut covers the rear assembly and is secured by a cotter pin

 

[Scott Danforth]

I would contact the place you had it rehubbed at

 

[heypawpaw]

Thanks for your responses. Prop is pin drive smooth shaft with prop nut and cotter pin. There were no prop washers on this motor when I bought it. Just checked parts diagram and no washers shown for this model FD20. I have ordered two new props one 9x10 and a 9x9 that way I can swap out when I have a second person with me. I will contact prop shop Monday.

 

[Sea Rider]

Don't swap props without a tach. on light applications one less pitch can rendered 300 to 500 wot revs. Test both props with 2 up and stay with the one that achieves max rpm closer to its max wot rpm range, will have excellent hole shot if in pursuit of that as opposed to slight more top end speed...

Happy Boating

 

[heypawpaw]

Thanks Sea Rider not looking for speed. With 9x10 prop top speed wot is 23 mph gps but I run it at 16-17 mph. I was thinking 9x9 would help plane out heavier loads, not looking to go fast just get it on top.

 

[jimmbo]

Allowing 15% slip you are running close to the top of the RPM range for that engine(4000 - 5000 rpm) with a 10 inch prop

 

[Sea Rider]

With 9 x 10 prop top speed wot was 23 mph gps, and the wot rpm achieved was ? Top speed is no all about, wot range is crucial and important to know. Need to know if with one of both props OB is working at least middle to max wot range factory stated with 2 up. Once there can go boating throughout the whole throttle range nicely. If engine doesn't count with a tach, go for one, Hardline induction hour/tachs are around $30, best investment ever...

Happy Boating

 

[heypawpaw]

Called prop shop and the guy said it's normal for hub to be slightly off center when pressed in and will center itself when put in gear. Ran motor in a drum putting in out of gear a couple times then verified prop not rubbing any more then ran a few minutes more in drum, then did same with second prop. Went out to bayou and rode for 15 min slow speed then rode around a few miles at various speeds, starting and stopping and prop works ok. New prop should arrive today or tomorrow and I can use old prop as a spare.