Reply
 
Thread Tools Search this Thread Display Modes
 
Old 03-13-2017, 11:46 PM   #1
Guru
 
AusCan's Avatar
 
City: Adelaide
Country: Australia
Vessel Name: Kokanee
Vessel Model: Cuddles 30 Pilot House Motor Sailer
Join Date: Jul 2012
Posts: 2,889
Gearbox rattling

I re-powered about 2 years ago with a 42 hp Vetus diesel (Mitsubishi based) and a ZF-25A gearbox.

The gearbox is a ~7 degree downangle design and a 1.98:1 ratio. The ZF-25A is one size up from what Vetus was originally offering with this engine.

The gearbox was always a little bit rattly when in gear at low rpm (850-1000rpm), although just recently it seems to gotten slightly worse (rattling from 850- 1200 rpm). The rattle is louder than the actual engine noise. Over 1200n rpm it is nice and quiet.

I've heard a variety of opinions from "this is normal" to "change from ATF to a 10/40 engine oil". A search on the web suggests this is a common problem with many gearboxes, but opinions vary considerably as to what to do about it, or if this is anything more than a nuisance noise.

Any suggestions from the TF forum?
__________________
Advertisement

AusCan is online now   Reply With Quote
Old 03-13-2017, 11:55 PM   #2
Guru
 
C lectric's Avatar
 
City: B.C.
Country: Canada
Vessel Name: Island Pride
Vessel Model: xxxx
Join Date: Oct 2007
Posts: 2,463
Could be the damper plate failing. It attaches to the engine flywheel and drives the gear input shaft often using springs for pulse and shock absorption. Eventually the springs fail and break. That can cause the noise and if left will fail completely leaving you without drive.
One possibility.
__________________

C lectric is offline   Reply With Quote
Old 03-14-2017, 06:15 AM   #3
Guru
 
AusCan's Avatar
 
City: Adelaide
Country: Australia
Vessel Name: Kokanee
Vessel Model: Cuddles 30 Pilot House Motor Sailer
Join Date: Jul 2012
Posts: 2,889
Quote:
Originally Posted by C lectric View Post
Could be the damper plate failing. It attaches to the engine flywheel and drives the gear input shaft often using springs for pulse and shock absorption. Eventually the springs fail and break. That can cause the noise and if left will fail completely leaving you without drive.
One possibility.
Could be, but I've never heard of one failing when new. (the noise was there right from the start) Less than 300 hours on the engine & gearbox now.
AusCan is online now   Reply With Quote
Old 03-14-2017, 07:06 AM   #4
Guru
 
City: Sydney
Country: Australia
Join Date: Jul 2015
Posts: 1,646
At low rpm the gears just aren't loaded up and the sound is gear slap when the gears are torqued up they load up and the tolerance between the gears reduces so dose the noise .
gaston is offline   Reply With Quote
Old 03-14-2017, 07:22 AM   #5
Guru
 
psneeld's Avatar
 
City: AICW
Country: USA
Vessel Name: Freedom
Vessel Model: Albin 40
Join Date: Oct 2011
Posts: 19,975
Had a relatively new one loose a punch out and thee punch out balled up and created all kinds of funny noises at different RPMs.

Not likely if your sound is constantly similar at the same rpm as you vary them...but a weird one for me.

Maybe yours isn't failing bit loosened up somehow?
psneeld is offline   Reply With Quote
Old 03-14-2017, 09:25 AM   #6
Guru
 
Ski in NC's Avatar
 
City: Wilmington, NC
Country: USA
Vessel Name: Louisa
Vessel Model: Custom Built 38
Join Date: Jan 2014
Posts: 5,354
Spring type torsional couplings are wear items. As they age, their performance degrades. A ZF 25 I think is a mechanical gear and it will be a noisy beast behind a four banger at low rpm.

Those gears are usually spec'd for sailboats where the noise is not an issue for various reasons.

There is gear rattle from the natural torsional reversals from the engine, but also fwd torque is what keeps the clutches in the gear engaged. The torsional reversals alternately engages and disengages the clutch, and that wears the mechanism out.

Try to avoid running where it rattles. Eventually you will get poor engagement in fwd.

Where noise would be an issue, hydraulic gears are spec'd with rubberized torsional couplings.

That's why they developed the "Velvet Drive" and trademarked it. Soft shifts and a quiet drive.
Ski in NC is offline   Reply With Quote
Old 03-14-2017, 09:35 AM   #7
Guru
 
LarryM's Avatar
 
City: League City, TX
Country: USA
Vessel Name: Pelago
Vessel Model: Wellcraft 3300 Coastal
Join Date: Aug 2011
Posts: 922
I think Ski nailed it. A mechanical gearbox like yours can be noisy under certain circumstances.

There is even a disclaimer in the latest ZF 25 A factory brochure:

Torsional Vibration and Torsional Couplings

The responsibility for ensuring torsional vibration compatibility rests with the overall propulsion system integration responsible party. Compatibility check of torsional vibration must include excitations induced by engine governor. ZF cannot accept any liability for gearbox noise or for damage to the gearbox, the flexible coupling or to other parts of the drive unit caused by torsional vibrations. Contact ZF for further information and assistance.


And from the ZF Repair Manual: ZF25A, ZF25, ZF45A, ZF45-1:

Troubleshooting

14. Chattering transmission noise mainly at low engine speed

14.1 The engine or propeller generates torsional vibrations in the drive unit which produces a hammering noise in the transmission.

14.1 Mount a flexible coupling with a different stiffness factor between en-gine and transmission; a coupling with a higher stiffness factor might be sufficient. Otherwise analyze the torsional vibrations to find out the re-quired stiffness for the coupling.


If your damper plate is OK (no loose springs), perhaps a flexible coupling might help mitigate some of the noise. Just a thought
__________________
Larry
M/V Pelago
LarryM is offline   Reply With Quote
Old 03-14-2017, 10:34 AM   #8
Guru
 
Nomad Willy's Avatar
 
City: Concrete Washington State
Country: USA
Vessel Name: Willy
Vessel Model: Willard Nomad 30'
Join Date: Oct 2007
Posts: 16,077
With the Kansaki gear that I had on my Yanmar 3cyl 12-15 yrs ago I only had the problem when the gear oil got fully warmed up. Comming back to the marina I was embarrassed. Sounded like the trans was falling appart.

At first I used heavier oil. Hardly made any difference. Then I used ATF and 90W gear oil mixed. Better.

Eventially I installed an oil pump and an oil cooler. Used the drain hole and the fill hole for circulation. Used a mix of gear oil, synthetic gear oil and some ATF. That did fine. Almost quiet.

Ran the boat for about 4 years after that and suffered no downsides. Other than the expensive oil pump. It was a 32V unit all made of bronze. It ran slow of course but that was ideal. Do'nt remember what I used as a cooler. I think it was a very small unit like a typical oil cooler. Probably hooked it up w a seawater intake hose. No more clatter though.
__________________
Eric

North Western Washington State USA
Nomad Willy is offline   Reply With Quote
Old 03-14-2017, 11:14 AM   #9
Guru
 
Northern Spy's Avatar
 
City: Powell River, BC
Country: Canada
Vessel Name: Northern Spy
Vessel Model: Nordic Tug 26
Join Date: Feb 2012
Posts: 3,023
I think Volvo had a rash of ZF 25 (they rebrand them MSS 25) failures behind their D2s. Not sure if it was infant mortality or what. I have the same box with a different ratio, and no issues yet.
Northern Spy is offline   Reply With Quote
Old 03-14-2017, 11:20 AM   #10
Guru
 
Northern Spy's Avatar
 
City: Powell River, BC
Country: Canada
Vessel Name: Northern Spy
Vessel Model: Nordic Tug 26
Join Date: Feb 2012
Posts: 3,023
I think I saw an upgrade to use a different damper plate. I should mention that I have a flexible coupling that the PO installed, that I kept during the repower. I think he did that when he took out his previous gear behind the BMW engine. But he trolled a lot.
Northern Spy is offline   Reply With Quote
Old 03-14-2017, 03:19 PM   #11
Guru
 
AusCan's Avatar
 
City: Adelaide
Country: Australia
Vessel Name: Kokanee
Vessel Model: Cuddles 30 Pilot House Motor Sailer
Join Date: Jul 2012
Posts: 2,889
Thanks for the suggestions, guys.

Yup - I'm in agreement about the noise being caused by torsional vibration.

I did add a flexible coupling when I did the re-power. Hard to say if it has helped the issue as I installed it when the package was new.


The gearbox also came with a cooler so it doesn't see very high temperatures, although it is quieter idling out of the marina in comparison to idling back in. I am thinking that the noise could be slightly higher recently just due to hot weather.

I guess this is one of the negatives of new lightweight engines. I should have kept the big heavy flywheel off the old Volvo MD17 and bolted it on the Vetus

Here's the flex coupling I have installed.
Attached Thumbnails
Click image for larger version

Name:	20150226_071306.jpg
Views:	67
Size:	66.3 KB
ID:	62735  
AusCan is online now   Reply With Quote
Old 03-14-2017, 03:37 PM   #12
Guru
 
AusCan's Avatar
 
City: Adelaide
Country: Australia
Vessel Name: Kokanee
Vessel Model: Cuddles 30 Pilot House Motor Sailer
Join Date: Jul 2012
Posts: 2,889
Quote:
Originally Posted by Northern Spy View Post
I think Volvo had a rash of ZF 25 (they rebrand them MSS 25) failures behind their D2s. Not sure if it was infant mortality or what. I have the same box with a different ratio, and no issues yet.
I did read about some ZF issues when deciding on which gearbox to use. In the end I decided to go with the down angle of the 25A to keep the engine somewhat level. Vetus was recommending the 15A but I decided to go one step up to the 25A (bigger is always better?). Maybe that wasn't such a good idea.

I also noticed that the ATF capacity of the ZF-25A is much less than the ZF25.
AusCan is online now   Reply With Quote
Old 03-14-2017, 04:00 PM   #13
Guru
 
Nomad Willy's Avatar
 
City: Concrete Washington State
Country: USA
Vessel Name: Willy
Vessel Model: Willard Nomad 30'
Join Date: Oct 2007
Posts: 16,077
Auscan,
I had a much more flexable coupling than the orange guys. And I changed my damper plate to one that had white plastic wedges instead of springs.
Sorry I should have mentioned that. Both the aforementioned items worked good. I think it was an RD coupling.

Re the 25A to 25A that probably was a good move. You may only have half the ratteling that I had.
__________________
Eric

North Western Washington State USA
Nomad Willy is offline   Reply With Quote
Old 03-14-2017, 04:47 PM   #14
Senior Member
 
The Other Gary's Avatar
 
City: Toronto
Country: Canada
Vessel Name: Adios Dinero
Vessel Model: Bayliner 3988 2 x 330 Cummins
Join Date: Sep 2016
Posts: 334
Read this thread from 2013


Damper Plates
The Other Gary is offline   Reply With Quote
Old 03-14-2017, 11:53 PM   #15
Guru
 
AusCan's Avatar
 
City: Adelaide
Country: Australia
Vessel Name: Kokanee
Vessel Model: Cuddles 30 Pilot House Motor Sailer
Join Date: Jul 2012
Posts: 2,889
Maybe I will shop around and see what is available for damper plates. I can then pull the gearbox and have a look at it. If it looks fine, i'll have a spare which probably isn't a bad idea.
AusCan is online now   Reply With Quote
Old 03-27-2017, 12:47 PM   #16
Veteran Member
 
Lady soft's Avatar
 
City: Trosa
Country: Sweden
Join Date: Mar 2017
Posts: 50
I had a ZF without a flexable coupling, connected to my 6,5 L Gm V8 diesel, and it rattled at lot, under 800 rpm, so I avoided to drive lower than 800 rpm, worked for me in the six years, I drove the boat. This was in my Coronet 31, and I'm shore it won't be a problem for the next owner. Lowest speed without noise, was 4,7 knots.if I wanted to drive slower I djust put her out of gear.
Lady soft is offline   Reply With Quote
Old 03-28-2017, 02:58 AM   #17
Guru
 
AusCan's Avatar
 
City: Adelaide
Country: Australia
Vessel Name: Kokanee
Vessel Model: Cuddles 30 Pilot House Motor Sailer
Join Date: Jul 2012
Posts: 2,889
Quote:
Originally Posted by C lectric View Post
Could be the damper plate failing. It attaches to the engine flywheel and drives the gear input shaft often using springs for pulse and shock absorption. Eventually the springs fail and break. That can cause the noise and if left will fail completely leaving you without drive.
One possibility.


Bingo!

I pulled the gearbox today and had a look at the back of the damper plate. It was a Centa DS damper plate. They don't have springs or roller pins like some. Just rubber bumpers. One set for low power dampening and another set for high load dampening. Guess what... the low power bumpers were flogged out.

The Vetus dealer will have a new damper plate for me tomorrow under warranty. I should be ready to go again by the weekend. Woohoo!
AusCan is online now   Reply With Quote
Old 03-28-2017, 02:58 AM   #18
Veteran Member
 
Lady soft's Avatar
 
City: Trosa
Country: Sweden
Join Date: Mar 2017
Posts: 50
Congratulations 🎊
Lady soft is offline   Reply With Quote
Old 03-28-2017, 05:24 AM   #19
Guru
 
City: Seaford Va on Poquoson River, VA
Country: United States
Vessel Name: Old Glory
Vessel Model: 1970 Egg Harbor 37 extended salon model
Join Date: Jan 2016
Posts: 2,185
Quote:
Originally Posted by AusCan View Post
Thanks for the suggestions, guys.

Yup - I'm in agreement about the noise being caused by torsional vibration.

I did add a flexible coupling when I did the re-power. Hard to say if it has helped the issue as I installed it when the package was new.


The gearbox also came with a cooler so it doesn't see very high temperatures, although it is quieter idling out of the marina in comparison to idling back in. I am thinking that the noise could be slightly higher recently just due to hot weather.

I guess this is one of the negatives of new lightweight engines. I should have kept the big heavy flywheel off the old Volvo MD17 and bolted it on the Vetus

Here's the flex coupling I have installed.
I am interested in your split coupling attaching to the prop shaft behind the red flex coupling, who makes that?

I am planning to get one like that
Are they available for velvet drives?

Buck Algonquin is one type I found, does yours completely split in half?
sdowney717 is offline   Reply With Quote
Old 03-28-2017, 06:55 AM   #20
Guru
 
AusCan's Avatar
 
City: Adelaide
Country: Australia
Vessel Name: Kokanee
Vessel Model: Cuddles 30 Pilot House Motor Sailer
Join Date: Jul 2012
Posts: 2,889
My shaft coupling was made by the same local company that made the flex coupling.

Poly Flex Group - Advanced Polymer Technology for Vibration Control - Steel Shaft Couplings & Spacers

They make them to suit most transmission flanges. Just measure up the diameter, bolt circle, etc.

I've never seen one that completely splits in half; the flange is always in one piece.
__________________

AusCan is online now   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off





All times are GMT -5. The time now is 10:13 PM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2006 - 2012
×