not sure what you use for a coupling, but I use one similiar to this
It has a rubber insert to reduce noise.
May help if noise is from connection.
If it was the connection though I would expect noise in both directions
Mark
From: "'cal' h20dragon@centurytel.net [electricboats]" <electricboats@yahoogroups.com>
To: electricboats@yahoogroups.com
Sent: Friday, August 28, 2015 8:18 AM
Subject: Reply to --- [Electric Boats] Notes on EV outboard lower unit noise
I tried exactly that, in the water reverse made less noise by a bunch. Now after the rebuild I haven't had time yet, but on land it sounds very much the same. That is not in water though !!! I might also look at a reverse prop pitch, but as a last trial sort of thing. My controller is expensive enough that I don't feel qualified to change anything on it. At least we did find that forward and reverse will take the same torque and pressure, whichever way it is set to work.
It can be much trickier to fix a vibration noise, when both major parts sound good tested separately -- than as they need to be hooked up to run. It may be that I sell that specific lower unit, and try for a different model year. That is real wistful thinking though, fix the easier stuff first is what we try for, sometimes accidents are good ones, har har.
I plan on trying different lower unit heights again, maybe that could change the pressure and/or the pitch or loudness – an easy trial fix in any case.
Thanks for your input, appreciate that as I might not have caught it ------- Cal
Sent: Thursday, August 27, 2015 9:28 PM
Subject: Re: [Electric Boats] Notes on EV outboard lower unit noise
Gets louder the faster I go, except in reverse
If your motor is DC, Have you considered leaving the shifter in Reverse and changing direction with motor polarity?
Mark
From: "'cal' h20dragon@centurytel.net [electricboats]" <electricboats@yahoogroups.com>
To: electricboats@yahoogroups.com
Sent: Wednesday, August 26, 2015 6:17 AM
Subject: [Electric Boats] Notes on EV outboard lower unit noise
Good Morning
Just a note on outboard conversions. Not all OBs are as equally appropriate to do. Mine has a noise, a whine as I mentioned before. Gets louder the faster I go, except in reverse, huh !! SO -- I just had the lower unit rebuilt, no change that I can tell, on land anyhow. I had tried thicker lube in the case, nope that just made the rebuild necessary and a bear to remove. Tomorrow we will try a different prop than the 12 X 12 I have on the boat now, borrowing some may show what's up in water testing.
The result at this point is that some ?? makes or models, or sizes – whatever - outboards do NOT make as good a donor lower unit. We all thought this would be a no brainer, and it is not so !! An engineer thought the two stroke motors, being louder overall, would be originally designed with way louder gears, since they are not heard in two stroke use. Probably some or all noise would not be tolerated in the newer four stroke lower gear train. Others say that is not so, since all the lower ends are helical gears, both forward and reverse, not straight cut at all, and should be quiet.
It would help if some others would add some outboard conversion details, or maybe I missed that part somehow. If I had known about any noise problems for instance, I might have chosen a different donor motor. The blown 50 Jonnyrude was here, so that's what we used.
More after we try different props, later --------- Cal
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Posted by: Mark F <mark.internet@yahoo.ca>
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