ZF63A port side transmission spins in neutral w/engine running

[Cliffm]

My Wife and I are in final stages of purchasing a 2006 Carver 36 MY with twin 8.1L and zf63A transmissions, 2.5 gearing.

The idling starboard engine output shaft does not spin in neutral, but the port side does?

Is this issue related to the reverse gearing for port side transmissions to make the port side prop spin opposite direction of the starboard side prop?

Both engines have low hours, but the port side is lower than starboard, 217hrs on port side, and 223 on starboard side? is the higher starboard hours likely due to port trans issues ?

anyone had similar issue with their Zf63A transmission and if so, what was the fix/cost?

thanks in advance for your reply's
Cliff & Beth

[bud37]

That certainly is low hours, for me 217 vs 223 pretty much the same......what does the trans fluid look like, you should have a mechanic look over things just like you got the surveyor. Could be as simple as an adjustment, but definitely needs to be looked at nevertheless......expensive boat well worth the money to make sure......good luck going forward.

[John Easley]

A friend of mine had the same transmissions on a different make and model. He had the same "issue," the port transmission allowed the shaft to slowly rotate when it was in neutral. A mechanic friend advised us to carefully try to grab the shaft while it was rotating in neutral. If we could hold it with hand pressure, then it was probably just the clutch slightly out of adjustment or it was turning by convection current and nothing to worry about. My friend was able to hold the shaft still with no problem. He later sold the boat and the surveyor had no problem with it.

Before anyone who is an actual transmission mechanic jumps all over my comments, I'm not a mechanic and am only relaying what one told us and we tried and it worked. Your mileage may vary.

[Cliffm]

Source of the post That certainly is low hours, for me 217 vs 223 pretty much the same......what does the trans fluid look like, you should have a mechanic look over things just like you got the surveyor. Could be as simple as an adjustment, but definitely needs to be looked at nevertheless......expensive boat well worth the money to make sure......good luck going forward.

had a survey from S3 Maritime, was no mention of shaft spinning in neutral (things that make you go hmmmm?) but had oil samples analyzed ...except that they didn't do the transmissions? Why I asked? because.... they smelled OK (eye's rolling now!)

my hull surveyor caught excessive drag on port side prop...which I went to the broker with, but was then told it was fixed, so we signed papers... only to find out it still spins.... now looking for fixes/trans experts.

[Cliffm]

Source of the post A friend of mine had the same transmissions on a different make and model. He had the same "issue," the port transmission allowed the shaft to slowly rotate when it was in neutral. A mechanic friend advised us to carefully try to grab the shaft while it was rotating in neutral. If we could hold it with hand pressure, then it was probably just the clutch slightly out of adjustment or it was turning by convection current and nothing to worry about. My friend was able to hold the shaft still with no problem. He later sold the boat and the surveyor had no problem with it.

Before anyone who is an actual transmission mechanic jumps all over my comments, I'm not a mechanic and am only relaying what one told us and we tried and it worked. Your mileage may vary.

I heard this.... but having first hand experience encountering a spinning shaft, i'm not attempting.

My hull surveyor pointed out during the haul out inspection that the starboard prop turned easily, and the port prop turned hard, this led to the witnessing the port shaft spinning while in neutral. Pulled shift cable, verified neutral detent position on trans aligned with helm shifter detent/cable position. Started port engine with trans in neutral, shaft spun, shifted forward /reverse, worked, but continued to spin in neutral, with enough force to overcome someone trying to hold a dock line position.

[bud37]

Source of the post My hull surveyor pointed out during the haul out inspection that the starboard prop turned easily, and the port prop turned hard, this led to the witnessing the port shaft spinning while in neutral. Pulled shift cable, verified neutral detent position on trans aligned with helm shifter detent/cable position. Started port engine with trans in neutral, shaft spun, shifted forward /reverse, worked, but continued to spin in neutral, with enough force to overcome someone trying to hold a dock line position.

Based on that alone, further investigation is required.....when people talk about the shaft turning in neutral, it is not to the point to move the boat by itself. You have a v drive setup I think......hopefully enough room around it for work to be done.

[John Easley]

My hull surveyor pointed out during the haul out inspection that the starboard prop turned easily, and the port prop turned hard, this led to the witnessing the port shaft spinning while in neutral. Pulled shift cable, verified neutral detent position on trans aligned with helm shifter detent/cable position. Started port engine with trans in neutral, shaft spun, shifted forward /reverse, worked, but continued to spin in neutral, with enough force to overcome someone trying to hold a dock line position.

Good investigation. Certainly starting to sound like the clutch is out of alignment or needing to be replaced. But, again... not a mechanic.

[denpooch]

If the engine is moving the boat while in neutral then it's not doing what it is supposed to be doing. Tranny rebuilds run in the 5K USD neighborhood. Good luck and proceed with caution.

[km1125]

This has nothing to do with the reverse gears, but is a transmission issue. There could be a seal bad in the valving or some clutch disc issues.

I would venture to say it's a clutch disc issue, as you noted that the shaft was hard to turn during haul-out. That indicates to me that something is staying engaged, if only partly.

As Denpooch noted, this could be a $5K issue, in having the trans pulled and rebuilt, or replaced. If you can't bargain with the whole price or having it fixed before closing, I wouldn't be too discouraged. Depending on your capabilities, you could have it corrected for less, or much less. When I purchased my boat it had a bad transmission. I was able to remove it, get the parts, and rebuild it over the winter for about $200. It's been working in the boat now for 25 years.

[Cliffm]

update:
Had Gunnar Hattaon (ZF trans authorized service center) from Hatton marine diagnose, issue = bad clutch pack. These ZF-63A-2.5 (for gas 8.1L) are identical, with starboard side running forward and port side running reverse, this is done at Morse Helm controls as both trans have identical shifting configurations. To rebuild is +$3K USD and new trans at FredWarner1.net = $2290.00 USD
Why is it bad??? don't know, but it is... so seller agreed to pay replacement fees.
Yacht Performance Center is performing the work which requires port side muffler removal to perform. Tony (owner) says the older carvers were easier as the engine hatch was over both trans & Motor. The newer ones, only uncover motor, trans comes out thru stairwell area, after removing stairs.
Awaiting scheduling appointment to have replacement done. Then back again Dec 10th for Bow thruster install at Yacht Performance Center.