ZF sail drive/Hurth transmission issue

[Ostinato]

I have two ZF SD 10 sail drives on Nanni engines - essentially a Hurth transmission mated to a sail drive shaft as I understand it.

When I put the starboard sail drive in reverse with the engine shut down it stops the prop from turning as I would expect but port sail drive does not. The prop just keeps turning. (Earlier it did do this but not anymore.)

Both sail drives have about 2200 hours on them and have had their oil changed in them routinely. The oil in both looks clear and there appears to be no discoloration. I have not felt any obvious slippage with the port sail drive in reverse or forward. I have folding props so, as a work around, I have been able to get the port prop to stop spinning long enough to get blades to fold by putting the drive into forward.

Having experienced a Hurth transmission failure in the past I expect this issue with the port sail drive does not bode well.

Does anyone have any thoughts about what is going on and what I should do about it?

[oldcal46skipper]

First, check your linkage. Have someone you trust steer and shift while you are down below observing the shifter. If it does not go all the way in gear, it will cause slippage and eventually wear the clutch plates. Be careful of moving parts.

Second, have you heard of Dr. Diesel? If not he often presents good tidbits from Foley. Dr. Diesel says, in a Down east accent, " Thems about a dollar an hour transmission. They cost about $1,500 to $2,000 and last about that many hours."

We do not rebuild them anymore as parts are $$$. If someone brings one in, we sell them a new transmission.

[Ostinato]

Checking the linkages was a good suggestion. I was able to get the port sail drive to lock in reverse by hand turning the linkage and then I made a small adjustment to the linkage arm on the transmission. Now it is back to where I first noticed an issue - that is the transmission lever has to be are beck as it will go to get it to lock.

Do you know if I can just replace the transmission or do I have replace the entire sail drive assembly on a ZF?

[oldcal46skipper]

You should be able to replace the trans without changing the saildrive. If you have maintained the zincs and changed the oil as needed, the sail drive should be okay. Assure there is no water in the saildrive oil. The lower seals on the saildrive should be changed at the reccommended interval, otherwise they will allow the oil to leak out when underway and water to enter when stopped.

[Ostinato]

That sounds promising. There is no indication of water in the sail drive at this time. So since I am in the Med, I guess it would be best to find a dealer here. Can this be done in the water or do I need to do it while the boat is out? ( I know stabilizing the drive would be best done while the boat is on land.)

[oldcal46skipper]

We have changed the gearbox out while in a calm anchorage or marina, but with great care. If it is time for your regular haul out for a bottom job, it could be done there.

Hurths, ZF's are built in Germany, Italy or Spain, so there should be dealers around the Med. Good luck. Glad I could be of assistance.

Tom

[Ostinato]

Thanks. Appreciate your advice.