Hurth ZF 10 M Transmission Problem - Any Advice on Removal ?

[sgtPluck]

We were just about to leave the dock yesterday to start heading south, but forward gear would not engage. Reverse would.

We tried manually moving the lever on the transmission to the furthest forward position with no joy.

I had just replaced the transmission fluid (which was a cloudy murky brown/purple color.) I thought I may have overfilled it, so I tried flushing the fluid out a few more times and making sure that it was at the right level. This seemed (maybe pure luck) to help, in that I could engage forward gear. But, if I rapidly accelerate while in forward gear it doesn't engage properly and slips - with the propshaft jerkily turning perhaps 1rpm. If I gradually increase throttle it works and does not appear to slip.

I've decided to try and remove the transmission (Hurth ZF 10 M, on a Universal 25 XPB - both 2008 models) and bring it for service (or get a new/reconditioned one.)

I'm wondering if anyone has any tips / basic instructions for how to remove the transmission?
I'm also concerned after reading http://www.cruisersforum.com/forums/...ures-8248.html and hearing from the boat two slips up from me who are on their 5th transmission. I believe I am correctly propped (could reach 2900rpm with the prop engaged) and it looks like my shifter cable is working correctly (although I need to make a closer inspection of that to ensure that it is perfect.) The transmission only had 150 hours on it, I don't want to repair it or get a new one, only to find that it also breaks after 150 hours.

Thanks!
-S

[cburger]

Maybe somthing as simple as the damper plate

[sgtPluck]

Thanks, and to get at that all I'd have to do (haha) is remove the bell housing? I suppose the damper plate would have some indications of damage if that's the case?

[cburger]

Don't remove the bell housing. There is usually a Hurth adapter plate bolted to the bell housing, remove the bolts slide the gear back out of the flywheel and slide the damper plate of the gear shaft and iinspect for broken springs, cracked plate etc. Just replaced ours as part of the engine rebuild. Hurths have a reputaion for being a robust drive, I find its usually better to look for the simple issue rather than assuming the worst. That being said the gear requires some maintainance to get long service life. If you find its problems with the plate and want to replace let me know and I can stear you to a good source for replacement plates. There are also companies that will rebuild your gear and offer a guarantee.

CB

[highseas]

If it works in reverse probably not the damper plate.Sounds very similar to my symptoms.I just rebuilt my ZF5M twice,once when I purchased boat,even though it only had 100 hrs.Boat was overpropped and maybe not fully engaging into gear.Rebuilt it again after I unknowingly anchored over heavy eel grass and wrapped it on prop and shaft, stopping shaft momentarily stripping my forward gear off and burning clutches.Seems to be fine now, but I am very careful not to get rope or heavy kelp getting wrapped again.Measuring for line cutter install.Getting good at removing and installing unit, but my engine is in sole so its easy to get at.Who said Hurths were tough?,(I know mine is a bit small,but that's what's in my boat)I hear many horror stories.

[sgtPluck]

At this point I am just trying to figure out how to get it out of there (apart from finding someone very strong who can hold me up by the ankles while I work on it upside down.)

There appears to be 6 bolts on the engine side - one at the top of the starboard/port side and two at the bottom. Does that seem right? The documents I could find on the ZF site and in my Universal manual aren't clear on this.

At the prop side it looks like I have 4 bolts going onto the propsaver/flexible coupling, although manually rotating that to get to the bottom bolt seems like it will be tricky.

[highseas]

I had to undo the rear mounts on engine and raise back of engine about 2 in. to get at the bolts on bottom of bellhousing,6 sounds about right.Removed starter,rotate shaft to undo coupler flange bolts.

[sgtPluck]

Thanks,
It was painstaking, but I managed to get all 6 bolts loose on the engine side of the transmission, but I'm not sure what to do next. If anyone can let me know if I'm on the right track I'd truly appreciate it.

I'm thinking that after loosening the bolts at 1) I may need to unscrew the pegs at 2) and try to slide that back towards the prop?

Sorry if it is a stupid question, but this is my first time and I'm trying to be careful not to do anything I shouldn't!

[Maine Sail]

A likely possibility is the forward thrust washer is worn as well as the clutch plates slightly warped or scored.

I will try and upload some photos of this type of damage later on. This can happen by leaving the gear box in forward while sailing, don't do it! It causes little bits of metal to wear off the clutch plates, drop into the fluid, then when you run it the metallic bits eat away at the forward thrust washer causing the gear box to slip and not engage..

I honestly doubt you have the room to get the gear box off the bell housing by sliding the shaft back. The spline on the input shaft is about 4-5" long and needs to slide out of the damper plate. You may need to slide the engine forward on the stringers and slide the shaft back. The damper plate should be replaced when you do the gear box. As always Murphy will see to it that it goes within 20 hours of replacing the gear box if you don't...

[Maine Sail]

Sorry for the SECOND post but I missed the RIDICULOUS time out for edit window..

Hurth Gear Box Pics:

Badly worn thrust washer that would certainly and did allow slip:


Combine that with burned and warped clutch plates and you have a gear box that needs a re-build:


Always lock in the opposite direction of travel OR allow it to freewheel in neutral. Oh and change the fluid at least yearly. Any metal shavings in these boxes kill the clutches and thrust washers. Even a short period of time left in forward gear while sailing is enough to cause some metallic bits into the fluid so if you do this a fluid change should follow.

[highseas]

I managed to slide my shaft back 1 in. and by tilting engine a bit up I slid it back far enough to separate.Don't undo pegs at 2, just undo 4 coupler bolts at 1, shaft should go back a bit,maybe loosen packing nut first.

[sgtPluck]

Thanks a lot all for the tips, and for the pictures.

Looking at my rudder, I'd say I only have around an inch to slide it back, unless perhaps I turn the rudder all the way to one side then I may be able to slide it out until the prop blade hits the rudder. I'll have to look into how I could raise the engine a few inches to slide the transmission off. It's very tight back there, it took me a couple of hours of wrangling just to loosen the bolts on the engine side.

[mofsubic]

dont worry about taking out. If you cant figure that out you skill might need some help. Also the shift lever is easy to take off, it removes with the side plate. remove 4 bolts. check the end of the shift lever shaft. sometimes the nutral pin gets week and need to be replaced with the sping, the cam on that shaft will always bring it back to nutral but engage will ship if the pin comes out of the nutral grove prior to engaging the clutch

[bryan and wendy]

Good luck, I will also be removing my box soon, it will be interesting to see how your job progresses.
There is a good workshop manual yo can download here

http://www.freedomyachts.org/downloa...e890ce418c7d5a

[mofsubic]

I have already done this 3 times. I have two engines on my boat.
Really it's easy.
Cheers