Torsional Vibration

[Pair A Dice]

Has any one heard of this phenomena??

I recently purchased a pair of Yanmar 8SY engines. They are to repower my 53C (stetched 50C). I paid my down payment in Nov 06 and got delivery on April 10th 07. The initial technical evaluation was to repower and us my existing zf bw165 transmissions. The engines were delivered with no mention of a concern about the bw165 boxes!! In fact I was told that the bw165 would be OK. Now on completion of the repower when I am ready to sea trial, Yanmar now informs me that they have a concern about the bw165 transmissions as to excessive torsional vibration. What are they talking about and who should pay the cost of purchasing and refitting th new zf 350 transmissions that they recommend?

Do I need a lawyer as well??

[jim rosenthal]

I would think that depends on whether you have any documentation of the claim that Yanmar said your old gears would be fine. If you do, then you probably have a case. If you don't, then I would think you do not. Unfortunately.

This doesn't sound like maritime law to me; it sounds like contract law. Isn't it basically a contract dispute?

Also, where is your Yanmar dealer through all this? Didn't he know what you were going to do and check out the install before the money changed hands?

I would look up the specs for each gear on the boatdiesel.com site, or through ZF, or ask ZF for the specs, and ask Yanmar to describe formally and in writing what their objections are. You can also suggest that you have Yanmar engineers and your own observers along on the sea trial and strongly suggest that if they have a concern about torsional vibration they bring along, at their expense, instrumentation to measure same.

I think I know what they are talking about- the coupling between the gear and the engine contains a vibration dampening device. It sounds like they may be worried that it isn't robust enough, or can't absorb the vibration that's going to occur.

I ran into something like this when I bought engines for Blue Note. The gears that were in my boat (ZF IRM220As) are also recommended for the Cummins 370D engines. That didn't stop the Baltimore Cummins guys from trying to sell me new gears, despite the fact that the ones I had only had 450hrs on them, or something like that, and had been carefully maintained and not abused at all. I told them I'd see them in hell first. I said I was willing to change the dampers out if they needed it, but that a ZF gear ought to last a lot longer than 450 hours and if they thought my gears were worn out, they had a lot of nerve trying to sell me the identical item, only new and $3500 each. If they thought the gears were so fragile then why were they pushing them in the first place? They mumbled something about having "fresh gears" and backed down. I also checked with the dealer to make sure that the Cummins warranty would apply to the engines if I used my original gears. Of course it would, they said. As long as they sign off on the application at the sea trial, it has to.

So are they just trying to sell you a set of gears, or do they have a legit concern here? I'd look at both scenarios.

[Pair A Dice]

Many thanks for your insight and advise. The local Yanmar dealer did the technical survey which included all details of the bw165 transmissions. What I am peeved about is that it took them 5 months to raise their concerns after I have spent in excess of $ 10,000 installing the engines. And will now have to spend another approx. $ 10,000 putting the new ones in -- not to mention the cost of the new gears. Surely if they are unsuitable now they would have been unsuitable back in November when they did the survey.

Anyway I am writing to the dealer and meeting with them to see if we can resolve the issue.

[Brian Degulis]

Did you do your own install or the dealer or a third party? I would think whoever did the install would be responsible to see that everything was compatable.

Brian

[AquaNav77]

Looks like someone didnt do his homework here on this issue. Every time that
a repower is contemplated and the same existing marine gears are going to be utilized for the new engines, a torsional analyzes must be performed in
order for compatibility. This analyzes is done by the engine manufacturer by request of the dealer. The analyzes not only looks at the capable input of the marine gear in terms of horsepower, but also will make a conclusion as to
whether a torsional coupling will be needed. Having said that, there are two
makes that are very prevalent on the market today, that is the Vulkan and the Centa Coupling. ZF prefers to use the Centa and Twin Disc actually has used both, however favoring the Vulkan. All this work is done at the very beginning of the project so that there are no surprises at the stage that you are at now. Furthermore, it is the action of the downward spikes of the con-
necting rods upon the crankshaft that causes this torsional vibration. The marine gear is on the receiving end of this situation. If these were brand new
marine gears, both ZF & Twin Disc would demand that this torsional analyzes be included in order to warranty their gear boxes. If this is not done and their gears are installed and destroyed because of an absence of these couplings you would be denied any warranty coverage. Hope this is good information for you.

AquaNav77

[Boss Lady]

You may also want to look at best industry practices. Repowers are done all the time and there is certain level of engineering due dilligence required by the engine and gear manufacturers. If this dealer is in the "business" they have to have on hand the requisite check lists for this survey from the manufacturers and they will require this to be done to ensure that their brand reputation is protected. I just love the way that some people try to put boat owners in a pressure situation to try and extract more money. It is unfortuneant that we find this tactic being used on a regular basis in the marine industry. Most people just pay, but I think there are only two reasons that something like this happens, incompetence or greed, and neither are good. If you get nowhere with your installing dealer, go up the food chain to Yanmar and leverage them, I would also let them know that you regularly communicate to over 1500+ yacht owners through an owners forum and that we are all watching what happens with your situation to see how this turns out. Keep us informed and good luck.

[Boss Lady]

Here is a good link, just in case you can't get good answers. http://www.vulkan24.com/vulkan.de/in...id=10012&pid=3