The dreaded HBW 50

[Fnagelmann]

Engine and prop shaft are all good. That said I am only getting about 1 or 2 knots regardless of engine speed. Might be transmission disks -- any other theories?

 

[Ed Valente]

Possibly the thrust bearing as well. Are you experiencing a loss of forward motion as you add power? If so, we may be in the same boat.

 

[Loren Beach]

Engine and prop shaft are all good. That said I am only getting about 1 or 2 knots regardless of engine speed. Might be transmission disks -- any other theories?

What model boat and engine model?
Yeah the little clutch surfaces in the transmission can wear and lost their grip, according to other owners. While our former Hurth 50 was working fine when we swapped out the whole drivetrain, it was also (just one more) reason to replace rather than rebuild the OEM 1988 drivetrain.
As noted by others, the viscosity of the trans oil can also make a difference. The last decade with it, I had changed to synthetic ATF, but it always stayed clean when changed, and I really do not know if that change made any difference.

More info and also even a photo will help others help you.

 

[Dave G.]

Products : Harbor Marine

Since 1979, Harbor Marine has been servicing the Pacific Northwest's boating and recreational needs.

www.harbormarine.net

 

[Fnagelmann]

Possibly the thrust bearing as well. Are you experiencing a loss of forward motion as you add power? If so, we may be in the same boat.

Adding power does not increase speed. Not sure about loss of forward motion.

 

[Fnagelmann]

What model boat and engine model?
Yeah the little clutch surfaces in the transmission can wear and lost their grip, according to other owners. While our former Hurth 50 was working fine when we swapped out the whole drivetrain, it was also (just one more) reason to replace rather than rebuild the OEM 1988 drivetrain.
As noted by others, the viscosity of the trans oil can also make a difference. The last decade with it, I had changed to synthetic ATF, but it always stayed clean when changed, and I really do not know if that change made any difference.

More info and also even a photo will help others help you.

Boat is 1970 e29 with m3-20 and HBW 50.

 

[Mr. Scarlett]

In my experience, a drop in replacement wasn't much more than the quote for a rebuild. Keep in mind that if one direction is failing the other one may not be far behind if the cause is improper use - going from fwd to reverse without pausing in neutral, or while the RPMs are up or sailing with the transmission in neutral (or in gear, I can never remember which is correct).

 

[G Kiba]

A quick check. Visually check the prop shaft rotation speed at idle. Give some throttle and check to see if the shaft speed increases. When my transmission was the issue, I could reverse fine but the boat would only go forward at idle speeds.

 

[Mr. Scarlett]

That was the major indicator for me too. Thankfully it was slack tide.

 

[Fnagelmann]

A quick check. Visually check the prop shaft rotation speed at idle. Give some throttle and check to see if the shaft speed increases. When my transmission was the issue, I could reverse fine but the boat would only go forward at idle speeds.

So presumably you rebuilt or replaced the transmission?

 

[G Kiba]

So presumably you rebuilt or replaced the transmission?
Well, I decided to forgo either of those for the moment but know that is likely in my future. In another post, I described what I did under the recommendation of the previous owner. I replaced the transmission fluid with 30wt motor oil. It's been working for over a year now and it works great... So far.
I figured that i would replace the transmission at some point anyways. So I gave it a try. The previous owner told me that his friend did this on a Catalina 30 and the boat has since has gone through 2 more owners without mishap. I told this to friend that is a heavy construction equipment repair technition who also owned a Catalina 30 with this problem. He said he wished he knew to try it. He took his transmission apart and shimmed the friction disks like he would on construction equipment. He didn't think the 30wt would cause any problems. I suspect that the seals may be incompatible with the oil. So i watch for leaks and save money for the replacement. Meanwhile, I get to sail my boat.

 

[Fnagelmann]

Possibly the thrust bearing as well. Are you experiencing a loss of forward motion as you add power? If so, we may be in the same boat.

That does seem to be the case. Increasing engine speed seems to slow the shaft (from observing in the dock so no verification from knotmeter)

 

[Fnagelmann]

In my experience, a drop in replacement wasn't much more than the quote for a rebuild. Keep in mind that if one direction is failing the other one may not be far behind if the cause is improper use - going from fwd to reverse without pausing in neutral, or while the RPMs are up or sailing with the transmission in neutral (or in gear, I can never remember which is correct).

What did you replace it with?

 

[Mr. Scarlett]

Technodrive TMC 40 gearbox 2:1 ratio.
If I remember correctly it was $1180 CAD and came with a bracket for the shift cable.

Note: the shift lever is on the Port side of the unit, and to go into forward the shift lever moves aft. In my case this meant re-routing the cable and reversing the linkage on the shift lever. The output shaft has a 3mm height difference but I can't remember which direction. It made no difference in my situation as I replaced the engine mounts at the same time - alignment was done from scratch.

Not sure what boat you have, but if the engine is coming out to do this, a few "while you're in there" things come to mind. Like tidying up wiring and plumbing, and cleaning/painting the space. Maybe even insulating it too. But slapping in a new one and going sailing is way more fun. Good luck!

 

[Mr. Scarlett]

Oh, and start spraying the coupler with your favorite penetrating oil now!

 

[Rocinante33]

But whatever you do, don’t get that penetrating oil on the rear seal of your transmission because that stuff eats up seals. Especially PB Blaster.

 

[Fnagelmann]

turns out the transmission was dead. Found a used one and a great mechanic to replace it. Now back in business!

 

[Ed Valente]

Curious to know where you managed to source a used transmission and which one.
I just had my ZF10M rebuilt and will be reinstalling it this weekend.
Glad to hear you’re up and running again!

 

[Fnagelmann]

The mechanic happened to have an HBW 50 so didnt have to make any modifications. Just a stroke of good luck. Hope your reinstall went well.