Avon SR4 Yam 50hp which prop?

[Nick Hearne]

Hi my new toy came with a 11.3/4" X 17 prop, looks in good condition but when you put the engine in to gear it shakes the boat with vibrations!
This stoops once more throttle is applied, I have spun the prop out off the water (just by using a hose to spin the prop not the engine!) & the prop looks to be wobbling but the spindle in centre looks true!
I was going to get it balanced, but B4 I spend any money is this the right prop for the boat? It will be used with up to 5 + dog in & around Salcombe + some water skiing & towing of the kids!

Nick

[Downhilldai]

Love the white SR4.

The vibes could be down to the centre bush of the prop having got distorted. Try removing the prop and running the motor on muffs, in gear to check the propshaft runs true, at idle RPM. If it does, then the bush is likely to be your problem. Check to see whether the prop hub is fouling against the gearcase housing. Seen a few do this over the years, when the prop shaft is actually true, but continued use can wear out the prop shaft bearings and oil seals.

[Nick Hearne]

Originally Posted by Downhilldai

Love the white SR4.

The vibes could be down to the centre bush of the prop having got distorted. Try removing the prop and running the motor on muffs, in gear to check the propshaft runs true, at idle RPM. If it does, then the bush is likely to be your problem. Check to see whether the prop hub is fouling against the gearcase housing. Seen a few do this over the years, when the prop shaft is actually true, but continued use can wear out the prop shaft bearings and oil seals.

Thanks I have had a better look & the prop is rocking on the spindle as though it is too big!!!

[Downhilldai]

That's odd. I assume the splines align ok?

Could you post a close-up pic of the prop, fitted to the motor, so we can see how the splines mate up?

[Nick Hearne]

Had a look last night & the splines in the hub only go back half way down (so the end nearest to the gear case has no splines!) I put it back together & did the castle nut up good & tight & it would seems good & solid now! I will have to see how it is at a later date.
But is this right that the spines are only in half the hub?

[Downhilldai]

Originally Posted by Nick Hearne

But is this right that the spines are only in half the hub?

Yes

[Nick Hearne]

Originally Posted by Downhilldai

Yes

Good, looks like someone took the prop off & didn't do the nut up tight after refitting then!

[Downhilldai]

Make sure they fitted the thrust washer