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Stu Jackson · 26-07-2015, 15:33

1. At only 355 hours you may not have to replace or rebuild it. The transmission fluid was filled up either because the PO was a jerk or he was doing just fine and had filled it, per specs, during the winter and didn't lower it to the dipstick for the season. Yes, you're supposed to do that, RTFM.

2. The C36 and C350 websites have lots of discussions about these transmissions. You might want to spend the time to read them, because I don't plan to retype all the great information that's there. For some reason those two boats have had more issues than our C34s, which have rarely posted about them. The C310 skippers on www.sailboatowners.com also have reported issues, check there, too.

3. Their conclusions are that you can replace the damper plate. There are two makers, one is better than the other.

4. The manual says neutral or reverse, NEVER forward. The Right Transmission Gear for Sailing - C34 You can do a search on just about any boating forum on "transmission position" and get this same input. It's a recurring theme...

5. Here's some more transmission info:

Transmission Fluid 101 Transmission Fluid 101

6. Don't forget to try it manually at the engine and check the slop in your control cable.

Good luck.

Robsocks · 26-07-2015, 16:01

Stu, thanks, sailboatowners.com is a wealth of info.

and yeah, I saw that was in the manual to fill during the winter. the darkness of the fluid and difficulty of getting at the drain plug makes me think it never got changed, maybe just topped up.

what does the damper plate do? I see that it's gotta get changed, but like the rest of the gear (which is pretty mysterious to me), I don't know if it's the problem. wouldn't it be a catastropic issue if it failed? or does it cause slippage as it wears?

Rob

Robsocks · 26-07-2015, 16:01

that's what I'm thinking. glad to hear it works.

Robsocks · 26-07-2015, 17:54

Has anyone ever tried to hook up a ZF 12 on a universal m25xpb?

Stu Jackson · 26-07-2015, 18:10

Quote:

Originally Posted by Robsocks

Stu, thanks, sailboatowners.com is a wealth of info.

and yeah, I saw that was in the manual to fill during the winter. the darkness of the fluid and difficulty of getting at the drain plug makes me think it never got changed, maybe just topped up.

what does the damper plate do? I see that it's gotta get changed, but like the rest of the gear (which is pretty mysterious to me), I don't know if it's the problem. wouldn't it be a catastropic issue if it failed? or does it cause slippage as it wears?

Rob,

You're welcome.

None of us uses the bottom drain plug on the transmission fluid, because, IIRC, it uses a crush washer which needs to be replaced. What we do is suck it out of the dipstick hole. I use a big plastic syringe and plastic tubing, others use turkey basters or hand pumps.

It causes slippage which just gets worse and worse, per the C36 guys. Noodle around there & the C350 forums. They have the experience, I (we - C34ers) simply don't. I have no clue why. I have 2900+ hours on our engine.

Also feel free to wander around our C34 tech wiki, that's where the RTFM sticker came from. We have the Hurth manual there and you can see what the plate does, or at least how it all goes together.

There's a ton of M25 series engine info there, too.

Good luck.

Dennis.G · 26-07-2015, 19:50

Just to say that the ZF (Hurth) transmission is a good as any other, and better than many out there. Best to address the issue with transmission instead of thinking about a trade-out to another brand.

Check linkage first, a common problem and easy fix. Worse case might be fitting with new clutch plates (i.e., a simple rebuild). Not really that hard to do. Of course if paying someone to pull transmission and do a rebuild you will be get a sizable bill.

Damper plates are normally replaced when doing a rebuild, but this is not a requirement, just preventative maintenance. I replaced mine, but could tell it was shot.

Robsocks · 30-07-2015, 02:58

ZF10 it is! Marine Parts Express in Maine seems to be coming through. order placed yesterday, hoping for quick delivery (and no hold-ups at the Canadian border).

I was very close to pulling the trigger on a Twin disc MG360 or MG 340, but frankly it came down to being able to find something in a short time frame and the first one I found was the ZF 10. ..strenghts and weaknesses on both sides from what I'm reading. on the Twin Disc side, I haven't read any horror stories at all, the ZF side is riddled with stories. on the ZF side, a much higher probability of perfect fit. I'm hoping that the bad stories about ZF are limited to poor maintenance. (to my future transmission: I will care for you, I promise)

I'm going to try to get the galley removed before the part shows up so the yard can get right at it. they're planning to lift the engine with the boom, I think.

wish me luck (and let me know if you have any more advice)

Rob

sailalibi · 05-08-2015, 07:56

I replaced my zf10 with a new zf12 on a universal 5424 (closely similar engine) years ago...still crusin!

Tessellate · 05-08-2015, 12:53

That does sound like clutch slippage / not engaging. Can you get into reverse easily? If so the fwd clutch is worn but not reverse.

I'm going through the same issue right now, but with a Hurth 150V (v-drive). A fair bit more expensive, and PRM doesn't make v-drives from what I can tell, so we'll be getting a rebuild for the 150V.

If I were you I'd get it looked at sooner rather than later. Not being able to get into forward gear when you really need it can be a big headache.

Quote:

Originally Posted by Robsocks

sometimes it goes into forward, but increasing the engine RPM's has no effect on the propeller shaft. I gather this is slippage.

Rob M.
Halifax, Canada
1984 Catalina 30 "albatross"

Tessellate · 05-08-2015, 13:03

Quote:

Originally Posted by highseas

Keep in reverse when sailing,neutral also causes wear.

I wouldn't keep it in reverse while sailing. The ZF (Hurth) manufacturer told me to keep it in neutral and not to keep it in reverse or forward. Yanmar (if your engine happens to be Yanmar) also says to keep the transmission in neutral.

Before I heard that advice from ZF Hurth I tried keeping it in reverse under sail one time, and after a couple hours, when our boat speed picked up to 6-7 knots, the prop started spinning (in reverse gear). Might be because the clutch plates were already worn before this point, but this was probably even worse for it than free spinning in neutral, so I stopped that experiment quick.

There seems to be a lot of disagreement on the Internet about transmission position under sail, but I would go with what the people who designed the transmission say to do.

Neutral shouldn't cause actual wear - the ZF transmissions are designed to free spin in neutral. If you don't like the prop shaft noise, you can always get a shaft lock.