Anyone upgraded from ZF10 or HBW100 to larger hurth/ZF?

[sgtPluck]

Hi,
After 2000 ICW miles burning through 2 ZF10s, I see the spec sheet online ..

http://www.marinepartsexpress.com/pr...07/ZF_10_M.pdf

and it shows that it is not rated for 'continuous duty' with a 25hp engine

Has anyone upgraded to a ZF12/HBW125 ? The ZF12 dimensions look slightly larger, but I'm not sure if I'd need to adjust my shaft or re-prop.

[Jim Cate]

Originally Posted by sgtPluck

Hi,
After 2000 ICW miles burning through 2 ZF10s, I see the spec sheet online ..

http://www.marinepartsexpress.com/pr...07/ZF_10_M.pdf

and it shows that it is not rated for 'continuous duty' with a 25hp engine

Has anyone upgraded to a ZF12/HBW125 ? The ZF12 dimensions look slightly larger, but I'm not sure if I'd need to adjust my shaft or re-prop.

Well, my inspection of the data indicates that it is just fine for 25 hp. The table shows that the tranny is rated for 37 hp continuous. Don''t quite see where you have a rating problem.

FWIW, we have ZF10 on our 43 HP Nanni, and I feel that it is marginal. Had to replace it just after we bought the boat, and had I known about the ZF12 I would have used one. Now have 2500 or so hours on it, and it is hanging in there. Fingers crossed!

Cheers,

[sgtPluck]

Hrm, am I reading it wrong?



It appears to show a range of 19hp to 27hp for continuous duty.

The ZF12 shows 25 to 37hp.

I think my usage over the last few months can be defined as continuous... came from New York to the Bahamas on the ICW, the longest motoring at one time being 29 hours straight.

[Cal_Pir8]

Pitch ZF. I had to send a new one back to them twice because it would leak. After it started leaking again as soon as it was installed, I pulled it apart and sealed it myself. Voiding the warranty, of course. 3 years later and it still hasn't dripped a drop. I am working aboard a gaff-rigged ketch and she has a twindisc transmission that has been moving our 100 tons for years. It seems to be bulletproof. Here is the pdf for the Twindisc model I think is the ZF-10 replacement. http://www.twindisc.com/Downloads/pd...IONS/MG340.pdf

[Jim Cate]

G'Day again SgtPluck,

Re the link in your first post, it shows ratings of 50 bhp for "pleasure" usage down to 37 bhp for continuous. The link in your second post didn't work for me... said I should go home... so I can't comment on it. But, I can't see where your numbers are coming from.

I do note that those ratings were at 5000 rpm. I suspect that they should be downgraded for lower speeds, since higher torque would be required to reach the hp figures. Undoubtedly there are folks with better knowledge lurking here on CF to comment on that.

Cheers,

[sgtPluck]

Hi,
It says 50 bhp for "pleasure" usage down to 37 bhp for continuous on the table at the top of the page on the first link, but if you scroll down a bit it has a more detailed table that seems to say something different. It appears to say that at 1800 rpm it is only rated for 19hp and at 2300 rpm 24hp - if I'm reading it correctly.
It looks like I'm going to stick with a ZF10 for now, because I'm not in a place where I can get the modifications to change gear type, and I'm in bit of a hurry - never a good thing!

[Jim Cate]

G'Day yet again,

Well, whaddya know? I hadn't tried scrolling down that link... sorry 'bout that!

So, it appears that my guess about RPM was on the right track. Anyhow, from their definitions of duty categories, it's a bit hard to define your usage as "heavy", unless your boat is one of those rare "Cape Dory tug boats. Their definitions are a bit arcane, but looking at them subjectively it seems like motoring your sailboat down the ICW would be somewhere between pleasure and light duty. You haven't told us what kind of engine you have, or at what RPM you cruise, but you might check your engines HP vs RPM curve and see just how many hp you are actually delivering at your cruise speed. It is likely less than you might think, and may well lie inside their specifications.

Meanwhile, I would also consider the possibility of misalignment or a bent shaft putting awkward loads on the tranny as another possibility for your problems.

As I said, our ZF10 has now got around 2500 hours on it, coupled to a 43 hp Nanni, and so far (touch wood) it's holding up ok. If your engine is only 25 hp it seems that the tranny should be ok in its ratings.

Good luck, and let us all know how it works out.

Cheers,

Jim

[sgtPluck]

Thanks,
I ordered a new ZF10, and I will treat it like a new-born child and hope that it holds up. I hope to get the old one rebuilt if and when I get to the DR so will have it aboard as a spare.
The alignment is perfect, so that's not the problem. It could easily be something else though.
The engine is a 2008 Universal 25, I usually cruise at 2200 rpm. It hadn't occurred to me that there was a power curve to consider.
If another one goes on me (and I use up the spare) I'll put a bigger ZF or a different kind of gear on the engine.

I'm not sure exactly how to interpret their (ZFs) definition of continuous duty, but it is this:

"Continuous operation with little or no variations in engine speed and power"

The longest straight run I did with it was 29 hours, but was doing 8 hours a day non-stop in general.

[Jim Cate]

Sgt,

One final thought -- when we were having our first signs of difficulty with the original zf10 I did some googling. Found a forum devoted to such trannies, and on it there were strong advisories touting frequent lube changes (at least every time you change engine oil) and the exclusive use of Dextron III grade ATF. We have followed that advice with the replacement gearbox, and it has indeed lasted. I have no idea if the procedures have anything to do with its survival!

Again, good luck.

Cheers,

Jim

[AquatiCat]

We had 1200-plus hours on one engine and 1300-plus on the other when we bought our catamaran last year. We had to replace the starboard transmission first, and then the port side tranny thrust washer went bad (port transmission would only deliver power in reverse). Both were ZF 10M 2Rs, purchased from Foley engines at the same time years ago by the previous owner. Amazing that they went bad within two weeks of one another (but at very different engine hours, because of differences in usage by the previous owner), but almost exactly what the Foley site says about "dollar an hour transmission" -- it costs around 1200 dollars and lasts around 1200 engine hours. Anything more than that is apparently great good fortune.

I'll let the forum know how long this pair lasts, but thank you for the recommendation on ATFs. I didn't want to have to dig it out of the Dr Diesel site again :-)

[delmarrey]

One thing not mentioned was heat. If the engine room get above 100º F you may want to install a blower. I had one with my old ZF and with a hose that blows right on the tranny.

Also use the Dexron VI oil

[Mirar]

Hello, It seems to me that matching any diesel with a "marginal" gear size is asking for trouble. It is becoming a common issue in our local harbor with the failure of these small ZF gears, and it appears that it is poor marketing practices to flog these little quirky units as something that will stand up to years of hard use. I guess it keeps the price competive on engine packages at the boat shows.
I helped diagnose one issue with a ZF10 after two early failures of the trannies on a friends boat. It turned out that the clutch linkage was not quite in adjustment , so when switching gears, it was never snapping into the proper detente. Over time this caused the gears
to fail (glazing on the plates)
That being said, I have put a ZF on my new boat, but it is rated for 200 hp more than I am plugging into it.
I agree about the twin-disc gears. Pricey, but literally last for ever.
cheers,Greg