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Old 10-21-2018, 09:14 AM   #1
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Noise when shifting

We just installed a new 50 hp Beta Marine engine and love it, it came with a new transmission, however when shifting there is a noticeable rather loud "clunk" sound. Doesn't matter if shifting from forward to reverse or reverse to forward. The mechanic says all small clutches do that. Any suggestions?
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Old 10-21-2018, 09:19 AM   #2
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Greetings,
Mr. T. "Any suggestions?". Get another mechanic?
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Old 10-21-2018, 09:20 AM   #3
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Brand and model transmission? Generally hydraulic trans are quieter shifting than mechanical trans.
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Old 10-21-2018, 09:33 AM   #4
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We just installed a new 50 hp Beta Marine engine and love it, it came with a new transmission, however when shifting there is a noticeable rather loud "clunk" sound. Doesn't matter if shifting from forward to reverse or reverse to forward. The mechanic says all small clutches do that. Any suggestions?
Assuming you need to do a repair, don't do anything that would void the warranty. Contact Beta direct and get their take on things.
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Old 10-21-2018, 10:40 AM   #5
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What gear are you using?

Most of those smaller engines use a mechanical shift gearbox like the ZF 15, ZF 25, etc. These are derived from the Hurth HBW 150, 250 etc. It is normal for these the "clunk" on a shift and rattle in gear at dead low idle. Most of these go into sailboats, where they are more tolerated.

Hydraulic shift gearboxes are much quieter. That is why the Velvet Drive is called Velvet Drive.

There are smaller hydraulic gears available, but I am not current on what is in the market now. Check ZF website.
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Old 10-21-2018, 11:14 AM   #6
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The small diesel on my last sailboat clunked when shifted. Seemed normal. never had a problem over 17 years
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Old 10-21-2018, 12:12 PM   #7
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What gear are you using?

Most of those smaller engines use a mechanical shift gearbox like the ZF 15, ZF 25, etc. These are derived from the Hurth HBW 150, 250 etc. It is normal for these the "clunk" on a shift and rattle in gear at dead low idle. Most of these go into sailboats, where they are more tolerated.

Hydraulic shift gearboxes are much quieter. That is why the Velvet Drive is called Velvet Drive.

There are smaller hydraulic gears available, but I am not current on what is in the market now. Check ZF website.
Interesting, Ski. We have a Velvet Drive on our port engine that is totally quiet when shifting. The Twin Disc (MG5011SC) on our starboard engine has a mild “clunk” every time it shifts into gear—even after lowering idle speed—and I’ve often wondered about it.
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Old 10-21-2018, 12:29 PM   #8
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A little noise is normal even with a hydraulic gear when shifting and at idle. Some more than others.

Compared to a mechanical gear, which is more like a bucket of rocks! (not quite that bad..)
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Old 10-23-2018, 06:22 AM   #9
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A high idle speed will make shifting louder.
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Old 10-23-2018, 09:07 AM   #10
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As Ski said a mechanical gear with mechanical clutches will give a good clunk in and out of gear. The problems arise when that solid clunk becomes a “chatter”.

If it really concerns you get it on record with the distributor that sold you the engine and gear. They should be happy to send a rep to listen if asked.

Be sure to follow the maintenance / fluid change schedule as outlined by Beta.
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Old 10-23-2018, 10:51 AM   #11
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Hi


Is the clutch a hydraulic or mechanical conical coupler, which belongs to keep a loud voice clunk like stendrivers at switches.


NBs
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Old 10-25-2018, 09:15 AM   #12
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It is mechanical, we have doubled checked all bolts, alignment, fluid level etc. It may be normal, we are considering adding a prn soft gear box. Any thoughts on that?
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Old 10-25-2018, 09:32 AM   #13
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Depends on how much the noise now bothers you. I ran a planing skiff with a 50hp diesel and mechanical Hurth box for about six years, every time I shifted it grated on my nerves. At that point going hydraulic would have required changing mounts, shafting and plumbing so I just sucked it up and motored on.

If cost is not that high, I'd go hydraulic.

What is a PRN soft box?
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Old 10-26-2018, 02:39 PM   #14
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It is mechanical, we have doubled checked all bolts, alignment, fluid level etc. It may be normal, we are considering adding a prn soft gear box. Any thoughts on that?
What Ski said. You might want to run the existing gear for a while. You might get used to it. I ran mine for 16 years.
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Old 10-26-2018, 06:53 PM   #15
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What Ski said. You might want to run the existing gear for a while. You might get used to it. I ran mine for 16 years.
We sent a video to the dealer, he wasn't concerned, just something we'll get used too. Love the engine, uses very little fuel. Thanks to all for the input.
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Old 10-26-2018, 10:25 PM   #16
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I had a Kanzaki gearbox (aluminum) that was manual. It was smal as was the engine. I was embarrassed every time I came into the harbor. The engine was a 3cyl Yanmar. I mixed up a brew of the highest viscosity gear oil I could find. That did help some but not enough.

I ended up buying and installing a bronze gear on gear hydraulic pump and plumbing it to circulate the oil in the trans to a heat exchanger and back to the trans. It worked. The viscosity stayed high enough to make the shifting reasonably quiet. One of my “mods” that was very sucessful. Expensive though.
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