Transmission wow's

My neighbor has the same boat with the same HO motors. He had to have his port transmission replaced after the 1st season. He had much different symptoms. Sometimes the trans would go into reverse, and sometimes it wouldn't. And, sometimes when it went into reverse, you wouldn't be able to tell it was in gear without giving some throttle because there was no 'positive' feel to shift.

Probably no help, but I just thought I'd pass on the info.
 
Any chance you (your mechanic) could swap transmissions- hook the starboard trans to the port engine and run it - see if the noise goes away?
Just a suggestion.
 
I do not understand why the engine is being brought into this? The engine is doing the exact same thing in forward that it is doing in reverse with no changes to the engine. It seems to me that if the difference in noise is from forward to reverse the issue would be from the trannies and aft. :huh: Since Aft of the trannies has been removed I would focus on the tranny
 
Hans said:
The engines both ran great before and after. No noise until gear was engaged. Most noise in reverse.
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At this point it's becoming very clear that we have only trany to blame. I'm very surprise that submitting all the facts from your findings to the company they still don't find anything wrong with the trany. Ask for a spare to do a proof of concept. I don't see other choice other than send yours back and have them re-test it more thoroughly.
 
Hans said:
I totally agree with you, but ZF keeps wanting to blame the engine.
Click to expand...

If the mechanic gives them official report that all checks off fine and it's time to focus on transmission again, it's hard to deny the facts. So, they'll have to proceed whether they like it or not.
 
Take some video to back up your claims and send it to ZF for review. With the shaft and prop out of the boat, that leaves engine and trans.

Run the video with the trans hooked up and in reverse and forward. Then run the video with the engine in neutral and revving it through the rpm range. That would seem pretty convincing to me that it was the trans.

Doug
 
I can't imagine this being your problem, but I'll pop the question related to the engine, how are your motor mounts? You have fairly new boat, but if for whatever reason your motor mounts are bad it might contribute to the vibration.
 
I think I may have the same problem. Low RPM load transmission noise that goes away at 1000 RPMs.

My Sea Ray mechanic thinks its the pressure plates which are held on by springs. The springs have started to fail so when not under load it vibrates like hell. As soon as a load is put on motors the noise goes away.

Maybe worth looking into this as a possible cause

Good luck
 
I just read your thread. I have diesel and I don't know if we have different transmissions but the transmission mechanic said he has seen a handful of failure with the zf torsional couplings. He is couplings on both engines.
He said that zf has had problems with the cummins/zf combo on the 46 and 48 dancers.
 
You may want to get with the 390 owner. If he/she is ameniable to having the Mech do the same to his boat that he did to yours and the results are the same, you stand a better chance with your Passport Warranty. See if the 390 owner is willing to give you the serial number from his tranny. It may be a bad lot of them between serial # aaa and zzz.
 
Hans,

Good luck, man. New trany has to solve the issue. It's after 3pm, so I hope you're enjoying your fixed boat.....LOL.
 
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