Hurth / ZF M15A Transmission Failures

[Svsilvergirl]

Oops , should never sail with trans in forward our neutral . Should be in opposite direction of travel

[highseas]

I don't particularly like my ZF transmission just stuck with it.First failure was previous owner install problem,second was my own fault.Now on #3,seems ok,but not overly confident.A Paragon gear I believe can be put in it's place,or an improved ZF model,but that will require moving mounts and cutting shaft etc,& more $.

[RBEmerson]

After sorting out an initial problem with a mis-mounted engine (sitting approximately 1/2" too high relative to the prop shaft), a problem repeated (or uncorrected) when gear #2 went in, the current gear has done very well through some Chesapeake Bay sailing and two trips down the ICW to Abaco and back (read "lots of motoring"). I added the cooler "just because", although I suspect it's not needed. Bottom line: once the engine/gear mis-alignment issue was sorted out, the gear's worked just fine.

[RBEmerson]

Originally Posted by Svsilvergirl

Oops , should never sail with trans in forward our neutral . Should be in opposite direction of travel

No. RTFM.

"IV Operation
2. Boat sailing, moving in tow or anchoring
When the engine is off, and the boat sails, moves in tow or is anchored, the propeller may turn with the water current."
ZF Marine HBW Series Operating Manual, pp. 8-9

Lubrication is achieved by oil (ATF) splashing as the transmission turns. There is no engine-driven oil pump (if there were, then the gear should be locked when moving by sail, tow, or anchoring in current).

[BOB FRYE]

We also have a 38 Landfall, had the HBW150V rebuilt 2 years ago and now it slips at 1100 rpms and higher.

Any thoughts?

[Jetexas]

Originally Posted by BOB FRYE

We also have a 38 Landfall, had the HBW150V rebuilt 2 years ago and now it slips at 1100 rpms and higher.

Any thoughts?

Open it up and take a look at the clutch discs. If they still have texture, you need to re-shim the ends of the shafts in the transmission casing, so it can't move forward.

[BOB FRYE]

Thanks for the tip. Will give it a try

[tomj]

Just returned from a 7 month cruise which included down and up the ICW from the Chesapeake to the Abacos (Bahamas)- approx. 400 hrs of motoring, and didn't have one transmission problem.... After our 5th ZF failure , we re-transmissioned with a Twin Disc which bolted right up to the original adapter plate, etc. etc. A relatively easy swap. We are planning on heading to the Abacos again this fall! Our advice (perhaps somewhat biased) is to use the ZF as a kellet for an anchor...

[BOB FRYE]

Where did you get the Twin Disk?

[highseas]

Originally Posted by Machinist Gary

I have rebuilt our Hurth Z drive on our C&C Landfall 38 12 years ago and I noted that there is a thrust washer which assists engagment on the counter rotating clutch shaft. My thrust washer was worn out (800 hrs). If you allow this transmision to freewheel in forward or neutral while sailing, the prop will apply back pressure to this sinter bronzed thrust washer and soon wear it out, resuting in to much play in the clutch shaft assembly and then it becomes no Shifty time. You can rev the motor a bit to get the clutch pack to ramp up tight but keep freewheellin these trannys while*sailing and you will be back to the shop. I carry the spare clutch plates (never needed) and a couple of new washers (2000 hrs and still locks up nice at idle). Once sailing with the motor off, shifting to reverse results in a slight clunk as the clutch ramps lock it up. I now sail with a Max Prop but I still notice it requires a shift into reverse to stop freewheeing even after the prop feathers.
Gary http://www.cruisersforum.com/images/...s/banghead.gif

Same thing my last rebuilder said.Always place in reverse,just to be safe.800 hrs. now without a problem.

[Sailmonkey]

Originally Posted by tomj

Just returned from a 7 month cruise which included down and up the ICW from the Chesapeake to the Abacos (Bahamas)- approx. 400 hrs of motoring, and didn't have one transmission problem.... After our 5th ZF failure , we re-transmissioned with a Twin Disc which bolted right up to the original adapter plate, etc. etc. A relatively easy swap. We are planning on heading to the Abacos again this fall! Our advice (perhaps somewhat biased) is to use the ZF as a kellet for an anchor...

We just returned from the Rio Dulce after replacing the 4th zf10m with a twin disc (and thanks to a major shipping snafu it's one size larger than the one I ordered). The last zf made it close to 200 hours, the new twin disc has over three hundred on it without a bit of trouble!!

[tomj]

I worked with:
David E Richardson
TWIN DIS SOUTHEAST, INC
11700 NW 101 ROAD, SUITE # 19
MEDLEY, FL 33178.

David was most helpful, and we did all the transactions via email. I did the installation myself. Send me a 'private message' and I'll send his email address.

Also, my installation of the Twin Disc trans is documented (sort of) on the Alberg 37 Web site (www.alberg37.org):

Specifically at:
SHEARWATER Receives a New Transmission

[BOB FRYE]

Will I do further damage if I just run at low rpms?

[Sailmonkey]

Originally Posted by BOB FRYE

Will I do further damage if I just run at low rpms?

It is more likely than not still slipping a little at lower revs, you just don't notice it. Any slippage will remove the sintered bronze facing on the clutch discs, and the tolerance is very small for lost material.

[RBEmerson]

Originally Posted by BOB FRYE

Will I do further damage if I just run at low rpms?

Yes. Once the clutch pack starts to go, the gear is done.

Who rebuilt the transmission? Were they ZF-trained or just guys who do transmissions?

FWIW, after all of the problems we had(*), the current ZF gear is holding up just fine. We did two round trips, via the ICW, from the Chesapeake to the Abacos including longer non-stop motors from Ft. Pierce to Fernandina Beach and Fernandina Beach to Charleston, and Lake Worth Inlet to Green Turtle Cay. With all of that and an extended Chesapeake Bay cruise last fall, the gear (knocking on wood) is working as it should.

- - - -

(*) Long story short, after ZF gear #2 crapped out (poor shifting, fried clutch pack, lots of metal in the oil), a ZF tech and I figured out that the engine, from the time the boat was built, could not have been properly brought into alignment (hard to miss a 3/8" mismatch between the prop shaft and output shaft when the mount adjusters and lock nuts are at the bottom of their travel - specs allow for 0.004" of error). Shortcuts to make the adjustments work failed, the engine dropped, and two gears died. After lowering the engine a full inch (modified the motor mounts), the engine and shaft could be brought into alignment. More importantly, the engine hasn't moved significantly since then.

Gear #1 was the factory original Hurth gear, Hurth gear #2 was installed by Zanhiser in Solomons, MD. ZF techs replaced gear #2 with ZF gear #3. Neither the factory (well, duh...) or Zanhiser spotted the alignment problem. ZF's tech found it and Central Marine in Deale, MD modified the motor mounts.

DISCLAIMER: I have no connection with ZF, Hurth, or any other company mentioned, save as a customer.