All,
Last season I started to get a subtle whining noise form what I thought was my port side transmission. It only happened at idle speed in gear. If I added any power at all, say 100 to 200 RPM, it went away.
The gears are 1:1.52 velvet drives behind SBC Crusaders.
I was wondering if the issue could simply be alignment? Can a really out of alignment gear cause something like this? I ask because I just got the quote to get the gear rebuilt, new cooler lines, cooler etc etc and it is a chunk of change. I also noticed the shaft on the port side was harder to turn by hand then the stbd.
I could roll the dice and put her in the water in April and hope that alignment fixes this or I can just pull the trigger and get it done now.
What do you think?
JD
Transmission Question B-28
Moderators: CaptPatrick, mike ohlstein, Bruce
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In Memory of Vicroy
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Every marine gear I've ever owned made some sort of noise sooner or later. My B31 has ZF IRM 220As behind the 6BTA Cummins and one rattles like hell at idle but it goes away at 800 rpm....its the clutch plates and on the ZFs its just one of those "live with it" deals. I know zilch about the velvet drives, but they use them in the B31s at Tropic Star and they all seem to make some noise at idle....of course most of their boats ahve DD 4-53s that are so loud the gears could be screaming at speed and you'd never hear them.
Not trying to be cute about a potential problem, but remember that the enemy of good is better and chasing subtle gear noises is probably not cost effective. My ZFs have over 2,500 hours - I've put over 2,000 of those on them, and the port gear has always rattled like hell. My advice would be run it, make sure the oil is okay, the cooler isn't leaking, etc. Does not sound like an alignment problem, and if you can turn the shaft by hand in neutral don't worry that one is easier than the other.....they will seldom be the same.
UV
Not trying to be cute about a potential problem, but remember that the enemy of good is better and chasing subtle gear noises is probably not cost effective. My ZFs have over 2,500 hours - I've put over 2,000 of those on them, and the port gear has always rattled like hell. My advice would be run it, make sure the oil is okay, the cooler isn't leaking, etc. Does not sound like an alignment problem, and if you can turn the shaft by hand in neutral don't worry that one is easier than the other.....they will seldom be the same.
UV
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Skipper Dick
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Wingnut,
I have ZF 63A tranny's and have the same situation. The port transmission rattled at idle (600 RPM) and as soon as I kicked up the RPM a bit, the noise went away. I don't know how many blogs I've read with the same problem and it seems always to be the port tranny.
I checked alignment and while checking that, found that my shaft was slightly bent and the prop dinged a bit, so while they were out, I ran the engine long enough to hear the same rattling with the coupling and shaft off.
Sometimes it does not make the noise at all. It's a head scratcher, but I've learned to live with it even after a career in the Air Force flying and listening for odd sounds. No one else on board seems to hear it but me.
UV's advice is good and sound.
Dick
I have ZF 63A tranny's and have the same situation. The port transmission rattled at idle (600 RPM) and as soon as I kicked up the RPM a bit, the noise went away. I don't know how many blogs I've read with the same problem and it seems always to be the port tranny.
I checked alignment and while checking that, found that my shaft was slightly bent and the prop dinged a bit, so while they were out, I ran the engine long enough to hear the same rattling with the coupling and shaft off.
Sometimes it does not make the noise at all. It's a head scratcher, but I've learned to live with it even after a career in the Air Force flying and listening for odd sounds. No one else on board seems to hear it but me.
UV's advice is good and sound.
Dick
Last edited by Skipper Dick on Feb 11th, '12, 14:14, edited 1 time in total.
1983 Bertram 28 FBC w/300 Merc Horizon
wingnut,
Each boat and Sit. is different and should be checked out. But, our boat in Costa Rica has velvet drives and for the first 3 seasons it made the same sound as yours. We looked at it tried to fix it and even had to rebuild the one tranny for another reason. It still made the noise. Just went away one day on it is own. Put plenty of hours on it without a problem.
Each boat and Sit. is different and should be checked out. But, our boat in Costa Rica has velvet drives and for the first 3 seasons it made the same sound as yours. We looked at it tried to fix it and even had to rebuild the one tranny for another reason. It still made the noise. Just went away one day on it is own. Put plenty of hours on it without a problem.
http://Www.GT-lures.com" onclick="window.open(this.href);return false;
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In Memory of Vicroy
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And remembrer, one gear is always running in reverse. On my Cummins 6BTAs, the port ZF is running in reverse to acheive the counter rotating we want. Some gas motors actually run "backwards" so one gear doesn't have to run in reverse. I'm told ZFs have the same gear ratio (mine are 1.53:1) in both forward and reverse, but lots of other brands have slightly different ratios forward/reverse.
In any event, as Dick points out, a lot of us that were pilots are very attuned to noise in machines that carry us along and its hard to break the habit of worrying about every little noise. Vibration is another thing, but just a subtle whine or rattle you can't "feel" in your butt is another. One of the dangers - or at least challenges - of twin enine anythings, boats, planes, etc - is trying to get both engines to run exactly the same. They never will, period. On the 6B Cummins the factory specs are plus or minus 5% nominal. 5% of my 2600 RPM wide open throttle is 130 RPM....same with temps, oil pressures, etc. So trying to get both moors to exactly match up is simpy chasing your tail.
Run it. Keep attuned for vibration or major variations in temps and pressures.
UV
In any event, as Dick points out, a lot of us that were pilots are very attuned to noise in machines that carry us along and its hard to break the habit of worrying about every little noise. Vibration is another thing, but just a subtle whine or rattle you can't "feel" in your butt is another. One of the dangers - or at least challenges - of twin enine anythings, boats, planes, etc - is trying to get both engines to run exactly the same. They never will, period. On the 6B Cummins the factory specs are plus or minus 5% nominal. 5% of my 2600 RPM wide open throttle is 130 RPM....same with temps, oil pressures, etc. So trying to get both moors to exactly match up is simpy chasing your tail.
Run it. Keep attuned for vibration or major variations in temps and pressures.
UV
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Harry Babb
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Good alignment is always a plus, so check and adjust the alignment as needed and keep an eye on it as normal maintenance.
Are you sure the noise is coming from the gear??? Could it be alternator or water pump bearings??.....or a seawater pump noise???
As far as rebuilding the Velvet drive I would not just do it "Just Because" of a noise.
If it were mine I would first check the oil and look for "Metal" particals then find out what the Hydraulic Pressure should be and install a gage and verify that the pump is in fact delivering the proper pressure. (Don't quote me but I think it may be in the 150/200 PSI range)
Next with the boat in the water.....shift into forward then back to neutral then into reverse.....if its responsive with only minimual lag then the pump and the control valve are okay.
With the shaft disconnected and the engine NOT RUNNING....grab the output flange and check it for movement both radially and axially.....you should not be able to feel any movement at all.
Then rotate the gear coupling and feel for "Roughness"....should be very smooth.
If all of that checks out...I would realign the engine and go boat riding.
As far as the differences between the ZF's and the Velvet Drives....the ZF's are made so that you can reverse rotation within the gear....just by running the transmission in reverse....but as far as Velvet Drives go "Forward is Forward and Reverse is Reverse" there only a couple of the older 72 Series gears that actually reverse rotation within the gear.....but still even then "Forward is Forward and Reverse is Reverse".
When you setup the velvet drives make sure that when you push the shift lever towards the input end of the gear the boat moves forward. Never Never use reverse to change rotation on a Velvet Drive. Reverse is a single clutch plate and is only intended to get you in and out of the dock.
The Velvet Drive is a very simple transmission and nearly bullet proof as long as its not overheated or over powered. I believe the last time I rebuilt a 1:1 the rebuild kit was less than a hundred dollars.
To tell one on myself.....My old Corvette engine had a nagging vibration so "Just Because" and without any diagnosis I decided to rebuild the engine. I replaced EVERY moving part in the engine and even went so far as to have the crank/flywheel/clutch assembly balanced.
Put that puppy back together and had the EXACT vibration.....it turned out to be the engine cooling fan......I considered that just one more tuition payment to the "U of HK" (University of Hard Knocks)
hb
Are you sure the noise is coming from the gear??? Could it be alternator or water pump bearings??.....or a seawater pump noise???
As far as rebuilding the Velvet drive I would not just do it "Just Because" of a noise.
If it were mine I would first check the oil and look for "Metal" particals then find out what the Hydraulic Pressure should be and install a gage and verify that the pump is in fact delivering the proper pressure. (Don't quote me but I think it may be in the 150/200 PSI range)
Next with the boat in the water.....shift into forward then back to neutral then into reverse.....if its responsive with only minimual lag then the pump and the control valve are okay.
With the shaft disconnected and the engine NOT RUNNING....grab the output flange and check it for movement both radially and axially.....you should not be able to feel any movement at all.
Then rotate the gear coupling and feel for "Roughness"....should be very smooth.
If all of that checks out...I would realign the engine and go boat riding.
As far as the differences between the ZF's and the Velvet Drives....the ZF's are made so that you can reverse rotation within the gear....just by running the transmission in reverse....but as far as Velvet Drives go "Forward is Forward and Reverse is Reverse" there only a couple of the older 72 Series gears that actually reverse rotation within the gear.....but still even then "Forward is Forward and Reverse is Reverse".
When you setup the velvet drives make sure that when you push the shift lever towards the input end of the gear the boat moves forward. Never Never use reverse to change rotation on a Velvet Drive. Reverse is a single clutch plate and is only intended to get you in and out of the dock.
The Velvet Drive is a very simple transmission and nearly bullet proof as long as its not overheated or over powered. I believe the last time I rebuilt a 1:1 the rebuild kit was less than a hundred dollars.
To tell one on myself.....My old Corvette engine had a nagging vibration so "Just Because" and without any diagnosis I decided to rebuild the engine. I replaced EVERY moving part in the engine and even went so far as to have the crank/flywheel/clutch assembly balanced.
Put that puppy back together and had the EXACT vibration.....it turned out to be the engine cooling fan......I considered that just one more tuition payment to the "U of HK" (University of Hard Knocks)
hb
hb
frank you are scarring me, please next time give me a call just like i will when i have to climb on top of that buggy top of the tower on that 51 bertram to replace antenna. normal procedure is to mount block on engine stand Minus flywheel housing,flywheel, and sae adapter. adjustable engine stand mounts are made to go directly into rear of block, using the same embossed threaded holes the flywheel housing would have went into.harry as usual has a brilliant idea if you want to modify a normal engine stand.
to eliminate the noises that will occur after a few hundred hours at the rear of gears you eliminate the damper plate . the vulcan drive has no springs and the matching sae. adapter is machine tool steel instead of aluminum . huge difference in performance available from ZF in RI.
to eliminate the noises that will occur after a few hundred hours at the rear of gears you eliminate the damper plate . the vulcan drive has no springs and the matching sae. adapter is machine tool steel instead of aluminum . huge difference in performance available from ZF in RI.
capt.bob lico
bero13010473
bero13010473
The reduction gear BW inline series is pretty quiet. They also don't have the issue normally related to the later offset gear boxes with drive plates, beside thats not a whine thats more like a can of marbles.
I'd look at the cutlass bearing also, old swelled cutlass bearings will do this, good suggestion Kevin.
Unbolt the coupling, slide shaft back and try and apply side to side and up and down pressure to the output flange of the gear. If its whining, there should be movement. This can be done with boat out of water.
When you bolt the couplings back up, at least check the face runout on the shaft side.
You can do a decent job of checking alignment out of the water.
If your shaft is to one side of the stuffing box or the other it could also be rubbing, Check the position of the shaft in the stuffing box.
Also check if you have flax packing if its old and dried out. You can get whine here also.
I serviced a ton of those gears and they either worked or they didn't there was really no in between. If the seals aren't leaking and the fluid gets changed once every two years and the screen gets cleaned at the same time the only thing that really killed those gears was shifting at high rpms.
I'd look at the cutlass bearing also, old swelled cutlass bearings will do this, good suggestion Kevin.
Unbolt the coupling, slide shaft back and try and apply side to side and up and down pressure to the output flange of the gear. If its whining, there should be movement. This can be done with boat out of water.
When you bolt the couplings back up, at least check the face runout on the shaft side.
You can do a decent job of checking alignment out of the water.
If your shaft is to one side of the stuffing box or the other it could also be rubbing, Check the position of the shaft in the stuffing box.
Also check if you have flax packing if its old and dried out. You can get whine here also.
I serviced a ton of those gears and they either worked or they didn't there was really no in between. If the seals aren't leaking and the fluid gets changed once every two years and the screen gets cleaned at the same time the only thing that really killed those gears was shifting at high rpms.
All,
Thanks so much for the feedback! I love this site...
I'd post more but honestly, you all know far more than I!! (still in the read, absorb and learn mode)
Both transmissions shift smooth and seem to work fine. Last season I did stick my head down in the area of the flange / trans and tried, as much as is possible, to determine where the noise is coming from. It sure seemed to be the transmission but I know how hard that is to nail down for certain
I'll try to align everything and check the cutlass bearing for play as you have suggested. The fluid is clean, no leaking and no metal shavings were seen last when I ran her in November. (blasted winter!!) Also the "U" cooler is new last season as I had some zinc anode bits stuck in there from accumulations over the years and replaced with a new unit. (I cleaned the old one and its a spare now)
And yes, I used to fly so am (overly) tuned into "what's that noise?" :)
Thanks again and I'll keep you posted!
JD
Thanks so much for the feedback! I love this site...
I'd post more but honestly, you all know far more than I!! (still in the read, absorb and learn mode)
Both transmissions shift smooth and seem to work fine. Last season I did stick my head down in the area of the flange / trans and tried, as much as is possible, to determine where the noise is coming from. It sure seemed to be the transmission but I know how hard that is to nail down for certain
I'll try to align everything and check the cutlass bearing for play as you have suggested. The fluid is clean, no leaking and no metal shavings were seen last when I ran her in November. (blasted winter!!) Also the "U" cooler is new last season as I had some zinc anode bits stuck in there from accumulations over the years and replaced with a new unit. (I cleaned the old one and its a spare now)
And yes, I used to fly so am (overly) tuned into "what's that noise?" :)
Thanks again and I'll keep you posted!
JD
I had the same problem with a low rpm whine. I developed the problem after realigning the engine and assumed the shaft was rubbing against the shaft log. I can't say for sure that the shaft log was the problem because I changed the packing and the strut bearing at the same time. Anyway, between the three repairs the whining went away.
Don't lend a hand to raise a flag aboard a ship of fools!
Again, thanks for all the feedback!
I got down to the boat yesterday and separated the flanges / couplers ( I have drive savers installed) I wasn't able to check the alignment with feeler gauges but I will do that next week. There did not seem to be any obvious or gross issues. The prop was not any easier to turn by hand. There is no play / slop in the cutlass bearings at all. (They should have only about 250 hours on them if that matters)
I turned the output flange of the trans by hand and it was smooth as silk. I also could not detect any play side to side or up and down but there was a small amount fore and aft.
Bruce,
You wrote:
"When you bolt the couplings back up, at least check the face runout on the shaft side."
Did you mean run out on the shaft itself? (or indicating on the flange?) My local mechanic suggested using a dial indicator to measure the shaft run out to see if it is bent or not. What would be a reasonable spec?
Thanks,
JD
I got down to the boat yesterday and separated the flanges / couplers ( I have drive savers installed) I wasn't able to check the alignment with feeler gauges but I will do that next week. There did not seem to be any obvious or gross issues. The prop was not any easier to turn by hand. There is no play / slop in the cutlass bearings at all. (They should have only about 250 hours on them if that matters)
I turned the output flange of the trans by hand and it was smooth as silk. I also could not detect any play side to side or up and down but there was a small amount fore and aft.
Bruce,
You wrote:
"When you bolt the couplings back up, at least check the face runout on the shaft side."
Did you mean run out on the shaft itself? (or indicating on the flange?) My local mechanic suggested using a dial indicator to measure the shaft run out to see if it is bent or not. What would be a reasonable spec?
Thanks,
JD
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