Hurth ZF10 Slipping

[sgtPluck]

I have an update on my original problem.
That third new gear I put in started failing after only 25 hours. I finally found the problem on my boat after locating two other owners who had the exact same problem, with the same hull, engine and transmission.
The problem is that the prop shaft is very short.. 18", and this increases the amount of tortional vibration encountered. The solution, as specified by Westerbeke, is to add a Centaflex DS flexible damper plate (which required a special adapter plate) to the engine. Apparently this solution has worked well for the other two owner. I just installed mine this morning. The engine did actually sound better already after installing it, the gear used to rattle a bit at low revs, it doesn't anymore.

[Tynesider]

Originally Posted by sgtPluck

I just installed mine this morning. The engine did actually sound better already after installing it, the gear used to rattle a bit at low revs, it doesn't anymore.

Hope you have finally bottomed out the problem mate and she goes for years now

Since refitting my new ZF 10 box the boat is fine and all appears well, but I have noticed a reduction in speed, I have to add about another 200 rpm to achieve the same knots as before.
My props is 15" and the engine a 27.5 hp, but I do have a longer shaft than you had, I guess about 2'.
The R&D drive/thruster plate is also new and replaced the existing unit.

By the way does yours go in with a 'clunk' when you go into gear?

Talking to people with the same box it seems the secret to long life is mainternace of the gearbox like changing the ATF often, I will change mine at the 60 hrs recommended and every 100 hrs there after.

Good luck
Mike

[sgtPluck]

Thanks Mike,
That's a very clean looking engine bay you have there, and it also looks like you have much better access than I do, I'm jealous.
Yes, my transmission does make a satisfying clunk when it goes into gear.

[Kranich]

Just a quick thanks for all the good info here! I also used the diesel cleaning method successfully after our ZF10M started slipping at 3.5 knots. Cheers!