Transmission issues

[Olivia Mae]

Toward the end of this summer we noticed a problem with the ZF15MA transmission on our boat. It may take several tries to get it to go into forward without slipping. It's fine in reverse. This usually happens cold when motoring out of our slip or starting up after being anchored. Once it's in gear it's good for the rest of the day without recurrence. I checked the linkage for the required amount of movement per the service manual. I also changed the fluid (did not look burned). Still having the problem. From what I've read, and a conversation I had with one of the large marine transmission rebuild shops, it looks like I"m going to have to either replace it, or have it rebuilt.

I have it out of the boat now, as we're out of the water for winter. I also removed the shaft, cutless bearing, pss seal, and damper for replacement in the spring.

Anyone else had similar issues? I so, what route did you go for repair? I also have been researching the Technodrive Twin Disc TMC60a transmission as a possible replacement. It looks like that one might fit, though it looks like it is about 7 mm longer, and it's already a pretty tight fit. Has anyone tried this transmission as a replacement and how did it work out?

Thanks for any info.

[wolfe10]

Sorry, can't address your issue directly.

But, I strongly recommend that the transmission fluid be changed at every engine oil change.

Only takes a few extra minutes with an old manual transmission pump.

Do not overfill.

[Olivia Mae]

Yes, we've done that, but we've only had the boat since last fall (so 2 oil changes). No issues earlier this season. The boat had only 690 hours on the motor when we bought it. Has 867 on it now as we did a trip from Lake Erie up the Detroit and St. Clair rivers to Lake Huron's North Channel and back, so more motoring than she's had in a while. Transmission fluid was pretty clean last fall when I changed it, but don't really know much about its history.

[Olivia Mae]

Just a follow up. I ended up getting the transmission rebuilt. Stroke of luck that I found a marine transmission rebuilder in our new home town of Summerville SC.( Chris Jones Marine). Chris is a quasi retired transmission tech from Fl , who is factory trained in all things Hurth and ZF.. He could do this one in his sleep, and convinced me that the ZF transmissions are good ones when rebuilt properly. He charged a reasonable price, making it worthwhile over a new one.

Finally got the boat back in the water a couple of days ago. All is well. Cant believe the difference the new damper plate made. I used the high deflection damper plate from R&D.

FWIW, the new prop shaft JUST cleared the rudder when I put it in without the cutlass bearing in, though it had to be persuaded some and it did scratch the rudder some even though I taped the threaded end first. Still, much easier than dropping the rudder or raising the motor.

[Boz]

Thanks so much for posting, and I'm not sure how I missed this thread, but we were experiencing the EXACT same symptons with our Hurth HBW 150A transmission. I went through the same steps of troubleshooting to no avail. Then just a month ago, our trip to the North Channel was cut short in Killarney, when the transmission began slipping out of forward drive at 1100 rpm. Finding your post has at least reinforced that our further troubleshooting led to the same conclusion...our transmission was just pulled at our marina, where it will be rebuilt by one of our experienced mechanics who has rebuilt numerous Hurths. Parts are about to be signed off on and ordered, just curious if you happen to know, did your rebuilder end up using a master overhaul kit or ordering clutch plates, etc all separately for the rebuild? And you mention the new damper plate, what difference did you notice??

Thanks again, hope our rebuild is as successful as yours!

Andy & Shari
Tradewind
C350 Hull #23
Midland, ON

[Olivia Mae]

Sorry for the late response. Just noticed this

Don't know what parts kit he used. He did replace the clutch discs, but the problem is caused by a worn thrust washer initially. The parts for the transmission are quite expensive. Expect around 1k just for parts.

The damper plate should be done too, unless it's been done recently. The new high deflection damper plate is much quieter at low engine rpm's.

I know project creep is a drag, but it's also a good time to replace the PSS seal (if it's more than a few years old) and do the cutless bearing if there's play in it. That's opening a big can of worms, though.

[Olivia Mae]

Also, if you end up in need of a marine machine shop for shafting work, the closest one to you is in Orillia, On. Don't remember name...universal prop or something like that. They can supply and fit and face a coupling, make a shaft, supply a cutless bearing (likely in stock). Nice people and very good.