[C320-list] New shaft

[Chris Brearley]

Adjusted idle up to 850rpm no vibration when dropping RPM quickly!
A great fix, thanks

Regards,

Christopher Brearley 

> On 18 Jun 2014, at 9:27 am, "Jeff Hare" <Catalina at thehares.com> wrote:
> 
> There's a difference between it shaking at low idle which they do (just look at it when idling!), and a rather harsh brief shudder that happens when powering down quickly.
> 
> The former is in the design.  The latter will certainly provide you with a need to put on new engine mounts more frequently.  It is most likely because you're powering down to an idle that is too low for your particular engine.  850-875 is about the minimum by spec., but it's a guideline not a specific number.    
> 
> Keep in mind that even though our engine *idled* very nicely at 860 (which is where it was before my adjustment) it went through a terrible shudder when it reached that RPM on powering down fast, after that it idled nicely again.
> 
> Ours is currently around 890-ish rpm and you can now power it down as fast as you like with no shudder.  Going into and out of gear is still very smooth.
> 
> So... Don't live with it.  Fix it!  Takes 5 minutes tops.
> 
> -Jeff
> 
> -----Original Message-----
> From: C320-list [mailto:c320-list-bounces at lists.catalina320.com] On Behalf Of Gene Helfman
> Sent: Tuesday, June 17, 2014 5:38 PM
> To: C320-List at catalina320.com
> Subject: Re: [C320-list] New shaft
> 
> Our mechanic on #398 (1997) says the Yamaha 3GM30F is called a "shaker" at low rpm, i.e., it's in the design.  He's worked on every type of diesel from a few hp to several thousand and knows his stuff.  Take home: live with it I guess.
> 
> 
> On Tue, Jun 17, 2014 at 2:34 PM, christopher Brearley <cjbrearley at gmail.com>
> wrote:
> 
>> Hi Jerry,
>> 
>> I have recently replaced my engine mounts with genuine Yanmah product 
>> and there is still the vibration when reducing RPM. Cutless bearing is 
>> also fine, so I am unsure of what is causing it. Reduce RPM slowly?
>> 
>> Chris,
>> 
>> WeaRitz@
>> #374
>> 
>> 
>>> On 17/06/2014, at 10:19 PM, jsheets at aol.com wrote:
>>> 
>>> Thanks all for the responses/advice. I suspect I will be adding 
>>> motor
>> mounts to my project list.
>>> 
>>> Jerry
>>> JellyRoll  #890
>>> 
>>>> On Jun 16, 2014, at 5:35 PM, Jim Brown <jbrown5093 at gmail.com> wrote:
>>>> 
>>>> You can check if the vibration is in the motor mounts pretty easily.
>>>> Uncover the engine and (watch out for the belts and pulleys) put a
>> longish
>>>> pry bar or big screw driver in the motor mount. Pull up hard. 
>>>> You'll be surprised about how much they raise up. With the motor 
>>>> mount stressed throttle up and if it is a mount the vibration 
>>>> should be gone or much better. Do each mount individually. Mine 
>>>> (2004) are very weak and when throttling down to idle it sounds 
>>>> like a bucket of bolts just above idle speed when there is 
>>>> significant vibration. With the mounts stressed-no noise at all. 
>>>> Getting ready to replace them . I believe that yanmar recommends replacement every 4-5 years (I suspect nobody does that).
>>>> 
>>>> Jim Brown
>>>> 
>>>> 
>>>>> On Mon, Jun 16, 2014 at 4:35 PM, <jsheets at aol.com> wrote:
>>>>> 
>>>>> Probably around 800 - 1000.
>>>>> 
>>>>> Jerry
>>>>> 
>>>>>> On Jun 16, 2014, at 3:11 PM, <tharrison at innovations-plus.com> wrote:
>>>>>> 
>>>>>> Just wondering what is you starting RPM"s
>>>>>> 
>>>>>> Ted - hull 424
>>>>>> 
>>>>>> -----Original Message-----
>>>>>> From: C320-list [mailto:c320-list-bounces at lists.catalina320.com] 
>>>>>> On
>>>>> Behalf
>>>>>> Of Andrew Santangelo
>>>>>> Sent: June-16-14 2:30 PM
>>>>>> To: C320-List at Catalina320.com
>>>>>> Subject: Re: [C320-list] New shaft
>>>>>> 
>>>>>> Jerry,
>>>>>> 
>>>>>> It could be related tot he cutlass bearing.  I have had this 
>>>>>> replaced
>> 3
>>>>>> times over the last 18 years on Dawn Treader.  I also had a drive
>> saver
>>>>>> installed for the Autoprop and it saves on wear and tear with the
>> engine.
>>>>>> 
>>>>>> Andrew Santangelo
>>>>>> 
>>>>>> C320 "Dawn Treader"
>>>>>> #333
>>>>>> Holland, MI
>>>>>> 
>>>>>> J22 "Blitzkrieg"
>>>>>> Elephant Butte, New Mexico
>>>>>> 
>>>>>> 
>>>>>> 
>>>>>> 
>>>>>>> On Jun 16, 2014, at 2:26 PM, jsheets at aol.com wrote:
>>>>>>> 
>>>>>>> I recently had a new prop shaft installed due to some previous
>> problems
>>>>>> with the old shaft. Since installed, on two occasions I have had 
>>>>>> a
>> strong
>>>>>> vibration of the shaft and transmission when starting out at low
>> speeds.
>>>>>> Once given more throttle it works itself out. Does not do it when
>> slowing
>>>>>> down from higher speed, only in early acceleration. Mechanic is
>> convinced
>>>>>> the alignment is correct. Says he thinks part of the problem is 
>>>>>> the
>> motor
>>>>>> mounts Yanmar uses, allowing for too much movement of the motor. 
>>>>>> Any thoughts or similar experience anyone can share is appreciated.
>>>>>>> 
>>>>>>> Jerry
>>>>>>> 
>>>>>>> JellyRoll  #890
> 
> 
> --
> Gene Helfman, Professor Emeritus
> Odum School of Ecology, University of Georgia PERMANENT address:
>    498 Shoreland Dr., Lopez Is., WA 98261
>    (360) 468-2136
>    genehelfman at gmail.com
> 
> "You noticed nobody gives a damn about beached minnows."
>