Hurth gear box failures

[jansan]

Having had two Hurth ZF 5 gearboxes fail in two years I am thinking of installing a ZF 10 unit as a replacement

Anybody out there had similar problems ? Anybody installed the ZF 10 unit and what was the result ?

My boat is the 28 MK1 built 1991 with a M 3 -20 Universal engine producing 18 HP

Also considering adding a water cooled jacket to this gearbox to reduce possibility of future problems.

Any comments or views appreciated

 

[Calif. Ted]

There's been a lot of discussion regarding high failure rate of the ZF5, I also have one behind a Perkins 18hp circa '94 that's still working fine (knock on wood). Concensus seems to be replacement with the ZF10 as the best solution, indications are that failure may be due to improper shims on the clutch (sometimes from the factory). Biggest hurdle in replacement seems to be the increased length of the ZF10. I'll attach a link to a discussion from the Ericson owners site that may be helpful.
http://www.ericsonyachts.org/infoexchange/showthread.php?t=6207

 

[jansan]

Hurth gearbox failures

Thanks Ted ------- the link to ericsonyachts was really informative.
Just for interest -------- does your ZF 5 have flexible drive couplings ? And is it water cooled ?
Regards Sandy

 

[Mike G]

Re: Hurth gearbox failures

Sorry to here you are having problems, I just changed the transmission on my boat (270 Catalina) it was not cheap. The shaft on the ZF 10 is 3/4 inches longer than the ZF50. We could not get the new transmission installed with the boat in the water, because the shaft had to be removed and cut. You can buy a rebuild kit but after talking to several deallers they recomended buying new. If you look at the cut-away of that transmission you can see why.
I did as some recomended on this site, is to change the fluid several times untill it comes out clean. It got me one more sailing season but a year later it failed.

 

[Mike G]

While under sail do you keep the transmission in reverse, it was recomended buy the factory to keep the transmission in reverse while under sail. I to asked about running coolling water to transmission but they said it was not needed on a sailboat my size.

The first problem I started having was the gearbox would ingage in reverse but not in forward. While waiting on a new gearbox I took the boat all the way out of the harbor in reverse, I turned a few heads at the club but a least I got to sail.

 

[jansan]

Hurth gearbox failure

Hi Mike

No I have always sailed with the gearbox in neutral ---- as recommended in the boat manual. However I appreciate that leaving it in reverse would save on wear of the propshaft rear bearing . Presumably you would try to have the prop sitting at 12 o`clock--- 6 o`clock ?

 

[Stu Jackson]

This one comes up regularly

Try this: http://www.c34.org/faq-pages/faq-transmission-position-sailing.html

 

[Calif. Ted]

Sandy, I don't have a flexible coupling and I really make sure alignment is always good. We only haul out every three years for paint and I always check alignment when it's splashed again. No cooling on the trans, doesn't really get hot even when motoring, just warm like everything else in the motor box. I've always kept it in reverse under sail, except a few times (who hasn't forgotten at least once) I think there's even a metal tag on mine that says to sail in reverse.
I've had the boat 5 years, it had 400 hrs and now has 880, I change ATF every 100 hrs. and it's always been real clean, guess I've just been lucky.

 

[jansan]

thanks Ted ---------- seems we both do about the same hours per season so guess I`ve just been unlucky. However now that the box is out I shall go down the route of upsizing to the next larger box the ZF 10 and accommodate the extra length with moving the propshaft back an inch. No doubt that will also involve readjusting the tilt of the engine on it`s mouintings to restore allignment. Hey ho.

thanks for the link Stu ---- nothing new under the sun, then.

Really appreciate all replies. Owning an American boat here in the UK isn`t too good when problems arise. Having technical support via the " owners community" has been a good experience