Damper Plates

Greetings,
Is there any "average" service life for a damper plate? Should they be changed under a preventative maintenance program at XXX (NOT what you think it means) hrs? Is there any "warning" before they self destruct?
I realise the service life is probably dependent on number of shift cycles or some such criteria. Any opinions?
Thanks.

RT Firefly said:

Greetings,
Is there any "average" service life for a damper plate? Should they be changed under a preventative maintenance program at XXX (NOT what you think it means) hrs? Is there any "warning" before they self destruct?
I realise the service life is probably dependent on number of shift cycles or some such criteria. Any opinions?
Thanks.

Click to expand...

I had a zf decide to self destruct wo warning at 2500 hrs. Smoked up the whole er. Upon inspection it looks like the rubber just had dry rot. The boat was also 20 years old at the time. ER temps probably cooked it. Boat was a sport fish with 6v92's and 5 previous owners.

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The life of damper plates is probably more to do w the way the engine is run and how the boat is set up.

For example fishermen that troll a lot have a lot more trouble than boats that don't. Torsional vibration stresses a damper plate w lots of back and forth motion (rotationally).

A damper plates ideal life .....
A 16 cyl engine w a heavy flywheel running on propane w a direct drive and an aluminum prop. Engine running at mid range w an oversized plate. Underloaded condition.

A damper plate's worst life ....
A big one cylinder engine w a rather light flywheel. A gear box w 5-1 reduction and a 5 blade bronze prop. Lots of low speed running w an overpropped condition and quick changes of throttle position.

So it's hard to tell when the D plate is ready to die. Also they don't reach a point of wear that can be measured. They have just seen too many back and forth motions and probably from metal fatigue they just fall apart. When they do there's usually a handful of springs in the bottom of the bell housing.

Sometimes they do make unusual noises prior to falling apart.

RT the sum total of my knowledge of DP's is about equal to yours judging from your post. 2 reported failures I've read about here and 2 my marina mechanic has repaired recently where originally mistaken for blown engine/broken crankshafts.

I asked my mechanic the same question and he shrugged and gave the ever definitive "it depends". Did say its not a bad idea to change it out if its been in there a while and you're working near it anyway.

As has been stated it is hard to predict if and when a damper plate will collapse.
They do wear and usually you will hear a bit of noise like rattly springs but on the other hand if they are old been subjected to extreme temps and stresses they will just go.
Always a good idea to change them out if you are doing any major engine or gearbox work, not to expensive and good peace of mind.
It is one of the spares that I carry on board.
I know I can replace it if it fails if it does when I am in some remote spot.
Mind you I would hope I could get to anchor some where or if not have very calm conditions as I have to remove the gearbox to access the plate and change it.
All in all about 6 hrs work.
Cheers
Benn

I went through several Vulcan tortional coouplings on my John Deeres connected to ZF gears. Blew rubber particles all over the engine room. It cleaned the clock off all the teeth of the coupler. First time it happened everybody thought I blew the tranny. Finally someone diagnosed the problem as the torsion coupler. Then I was able to tell when they were ready to go when I found rubber shavings around an access hole to the flywheel. I went to silicone couplers and they have lasted ever since. The heat and chemical atmosphere eats the rubber I think.

Ford Lehman dampers are spring type. Bob Smith recommends they be replaced after 2500 hours.

Greetings,
Thank you all for the input and insights. I have no idea when, if ever, the DP's were changed. If Bob Smith recommends 2500 hrs., that's good enough for me. There are about 4500 hrs. on the Hobbs meters at the present time and I DO have new DP's purchased a couple of years ago, as spares, from AD. Oh dear....Yet another maintenance item to be added to an already lengthy list.
As a side note, my maint.' list USED to be just one or two items but since some of you b*stards have posted pictures of your pristine ER's, the "LIST" has morphed into an item growing faster than the national debt!!!! THANKS A LOT!
Just looked it up. It's Mr. FlyWright's fault for starting the thread....WE are not amused...

I've only been towed twice in 50+ years on the water (outboards excepted) and damper plate was the cause both times. They can fail w/o warning.

I urge you to look at the plates that PMI sells. No springs to rust & rattle and a "get home" feature.

When I rebuilt my BW tranny 6 years ago I replaced the damper plate because it was exposed and easy to do. At $120 from ADC is was a no brainer.
The plate looked like it was in good shape still at 3700 hours behind a Ford Lehman 120.
I sold the old one for $20 and bought some beer.

Brooksie said:

I urge you to look at the plates that PMI sells. No springs to rust & rattle and a "get home" feature.

Click to expand...

PM&I damper plates;

Catlog: Marine Damper Plates - Damper Plate Marine:

Or here:
-- PYI Inc. Max-Prop PSS Shaft Seal Seaview Radar Mounts R&D --