Shifting problem on CD 31 ZF-10M-R Hurth Transmission

[jen1722terry]

Hello fellow CDers!
A problem appreared with our transmission just before haul-out. It is an almost new Hurth ZF-10M-R trans installed in 2012 on our original Universal M-25-5421 engine.

The problem is that the trans will not quickly shift into the forward gear. It seems to hesitate and can take as much as 15 seconds to shift. The problem seems to be worse when the engine is cold and usually goes away when the engine is well-wamed. The Trans fluid is at the normal level and shaft alignment appears fine.

We ran the engine a lot this summer coming from NH over to Nova Scotia and, on a few occassions, started the engine in forward or reverse. Any ideas?

Many thanks, in advance.

Jenn and Terry

[Steve Laume]

When I had shifting problems with my transmission a few years back. I talked to the rep at the Mystic Wooden Boat Show and the first thing he told me to do was change the fluid. The first thing I would check in your situation is that the lever is fully engaging the transmission. You could pull the cable right off and try shifting it with just the lever to rule that out as a problem. If it does not fully engage it will wear the clutches and create serious problems. My transmission was engaging all the way but the clutches had worn in 20 some years. I got through the season by changing the fluid as suggested with a bit of sluggish engagement but no complete failure. Then I had to pull the thing and have it rebuilt during my winter haul out. On my Universal, you had to pull the engine to take off the bell housing to get at the bolts on the inside to remove the transmission. Not a great design. The clutch plates are only a couple of inches in diameter and are the first thing to go.

I hope you just find that you need to adjust your cable and all will be well, Steve.

[Phil Shedd]

Late this summer my transmission started to slip or would not go into forward when shifted or was slow to engage. Because of this I decided to rebuild the tranny.

The whole process was interesting to stay the least. I disconnect the shift cable ,cooling hoses ,remover heat exchanger, disconnected the shaft and oil pressure block. Then I jacked up the engine( by using threaded rod and square tubing) so I could get at all the bell housing bolts to get it off. Once all the bolts were out the bell housing and tranny came out through the port locker. The unit is not heavy as it is all aluminum.

I cleaned the housing and transmission exterior then drained the oil . The oil was black a good sign things were not right . The rebuild did not take long about four hours. Important to have a wheel or bearing puller. Was able to get the repair kit in the states at Hales . The kit is for a number of transmissions so for the #50 you only use half of the bands. Before putting the unit back in boat I gave the boat a real good cleaning as there had been a oil spill a number of years ago and there was a lot of gung under the bell housing.

Then put the unit back in boat with out too much trouble. The only problem is getting this older large body into smaller lockers and into the engine compartment .LOL

SO now the unit is back in and every thing is back . I have started the engine to winterize it but have not shifted the transmission until it is in the water next spring. Was worried that the bearing might get hot with out water. So we will see in spring but do not think there will be a problem.

If the oil is starting to get dark you may be having band slippage .

Phil

[Jim Walsh]

I applaud your efforts to remove and rebuild the tranny. You make it sound relatively routine but I know it must have been trying at times. Good on ya.

[jen1722terry]

A belated warm thanks for the info, guys.

I'm hoping I don't have to pull the trans, as it is only a few years old. Before we leave the boat at the Nova Scotia yard for the winter and head back to the New Hampshire home, I plan to crawl in there and drain the fluid and check to see if the cable is slipping or otherwise damaged. Then I'll fill the trans completely with new fluid for storage and drain it down to the correct level in the spring.

I have to get an exact measurement of the shift/throttle cable anyway so I can order new ones back in NH. The present ones are not anywhere near new.

Thanks again, and y'all have a pleasant T-Day,

Terry