Driveline COUPLER parts question

[swatski]

Yamaha stated they made changes to the mounts and (driveline) couplers for noise reduction. So, as a part of the sound proofing package they refer to as "quiet ride", Yamaha " introduced a new coupler material in the link between the engine and driveshaft".

I have been looking to identify the relevant parts of this "package" in order to see what if any could be retrofitted into older boats. This has been confusing, to say the least, but I think I have the listings for the relevant parts and prices, as below (from yamahapart.com).

Looking at these parts, quite a difference I would say. For example, the new flange coupling appears a lot bigger (heavier?). I could see this having a substantial effect on vibe/noise reduction and transmission through the pump and the hull.

Does anyone know anything about these parts? can they be seen anywhere, even just pictures? Could anyone with Yamaha contacts comment on the materials? Are these cast or billet, etc., what is the approx weight? Is rubber a different compound?

Here are the relevant 2016 Parts (as listed for 242LS E) equipped with "quiet ride" technology:

Intermediate bearing side (aft):
#1 Rubber Shaft Coupling: 6AP-4581J-10-00 $113.87
#12 Flange, Coupling 1: 6AP-45593-00-00 $116.14

Engine side (fore):
#12 Flange, Coupling: 6AP-45813-00-00 $76.69



For comparison only, here are the 2012 Parts (as listed for boats NOT equipped with "quiet ride"):

Intermediate bearing side (aft):
#1 Rubber Shaft Coupling: 6AP-4581J-00-00 $133.10
#12 Flange, Coupling: 6S5-45593-00-94 $57.04

Engine side (fore):
#13 Flange, Coupling: 6S5-45813-01-94 $108.32




The question is: how much real difference in reducing the overall vibration and noise in new boats can one attribute to these new couplers?

(Please, please, please, I know... about soundproofing the hatches and sealing compartments, and I can crank the stereo and ignore the noise..., etc. - that is not what I am asking).

 

[Julian]

I can't comment on these parts. All I can say is that when I discussed with Yamaha why they hadn't put the noise reduction in all their boat models for the 2016 year (something we were hoping they'd do), the response was - "this wasn't a single change, but a slew of changes throughout the boat to achieve this effect". Also, our Yamaha contacts are all about selling new boats, and although they use the forum to get ideas on what to do, they have less than zero incentive to clue us in on how to achieve these results in older boats (they want us all to buy a new one!).

That said, I'll bet this coupler would make a difference, and the problem you face is just how much! No one will know until such time as someone gives it a go by spending the money on the parts (if anyone ever does). The best approach might be to spend a ton of time crawling all over a new boat to eyeball any obvious changes (sound proofing material, engine mounts, couplers, hull/wall sealant etc).

It sure would be cool to have a kit that provided a set of stuff that would get an owner there....if anyone were to do that, it would be @JetBoatPilot !

 

[swatski]

The new parts can be sourced fairly cheaply, powersedge.com the whole 3-piece coupler set runs little over $200, so the issue is primarily the install - pulling the engine? though it may be possible to swap the coupler by just sliding the engine forward.

I never heard of a driveline coupler failing in a boat. (Skis - that's a different story.) So - the only reason I can think of for Yamaha to redesign that part must have been to combat unwanted vibrations and noise. I wish I had a Yamaha engineer friend on speed dial.

 

[swatski]

So, not sure how I missed it, but apparently the new 2016 190 series (SX/AR and FSH190) are all equipped with the new coupler pair (Rubber Shaft Coupling: 6AP-4581J-10-00 and Flange Coupling: 6AP-45593-00-00)! That new coupler seems to be the only part of the new "quiet ride" technology Yamaha uses in the 19'ers. They carry the same hull as 2012-current, when the 190 was first introduced. The articulating keel is a modification of the ride plate part (not used in twins), not the hull. Please correct this information, sourced from secondary suppliers here.

I will have to hitch a ride somewhere to see what it does! (probably not in FSH, as the cockpit configuration is different enough to change the acoustics).

And, here is the puzzler: the 2016 AR192 uses the old style coupler (6AP-4581J-00-00 and 6S5-45593-00-94)... as do all new SVHOs and other supercharged skis.

Together, this indicates the new couplers where not introduced to combat stress/fatigue of the materials. I am really curious about their contribution to the "quiet ride", but at this point am going to wait until I can get a ride in one of the new 190s .

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[CrankyGypsy]

these couplers are the exact same design as the rear wheel dampers used in sportbikes. the only purpose is to prevent the torque from breaking the hub during initial power delivery, not to silence anything.

the rubber is completely isolating one side from the other, so there is no way for any substantial noise to originate from these three parts. the noise has to be coming from the pumps (impeller rattle) and resonating back through the shafts ...which would explain why everything is quieter/muffled when in the water, being buffered.

 

[swatski]

@CrankyGypsy good points, no argument here. Some time ago Vibratech couplers were produced and used in skis, recommended as one of the Group K mods for racing boats, not so much for noise reduction but to preserve crankshafts. However, they were found to reduce vibrations and harmonics aside.
https://jetboaters.net/threads/fluid-balancer-driveline-coupler.8172/
Our engines have extremely low mass / inertia moment, for the power they generate. If the new couplers have more rotational mass, that would help.

From what I understand, with fancy name "quiet ride", Yamaha might have changed the material to manufacture the damper (rubber part).
What made me think about, a quote about the "quiet ride" in boattests or such:
http://www.personalwatercraft.com/m...nnovations-in-its-sport-boat-lineup-1283.html
(Yamaha is) " introducing a new coupler material in the link between the engine and driveshaft".

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[CrankyGypsy]

hmmm, I can't imagine how the damper material makes much significance. once the driveshafts torque up against each other, the cushion essentially becomes irrelevant.

I have been thinking about the "update" to the coupler assembly. the new halves appear to contain less total metal material. so lighter, yet stronger due to the outer rim.

I would think LESS rotational mass would be desired as that would reduce the shaft deflection inertia, and therefore less pump rattling.

 

[swatski]

One usually thinks of lightening rotating mass for added accelleration etc, but... it comes at an expense of lot more vibration and prop shock.

Compared to our engines, your standard V8 engine will have twice the crankshaft piston and rod weight, heavy steel flywheel etc, all which add a huge amount of weight to the rotating mass of the engine, makes the engine a little slower in getting to peak RPMs and horsepower, which can be a good thing, reduce the shock in the system that breaks parts.

I read somewhere that the Sea-Doo rotating mass is more than 10 pounds heavier than the 1.8l Yamaha engine and you can apparently feel and hear the difference (I don't have any personal experience - but I would like that!). And R&D sells a billet coupler with added weight that supposedly helps with the cavitation issues as well... who knows.