ZF-10 Reluctant Reverse?

[AndrewIC]

I have a ZF-10 gearbox (HBW100 replacement), and for the last few days it has been reluctant to engage reverse gear. Forward is fine, but when putting the lever into the reverse position either nothing happens at all, or there is a delay of ~1-2 seconds then the usual "clunk" as it engages. Once engaged reverse works fine. Forward gear works fine.

 

The gearbox ATF level is fine, and is changed according to the schedule in the manual, and I have changed it again today to no apparent effect. The problem seems to be worse in the morning (when cold??) and improves - that is, reverse engages promptly and every time - as the day goes on.

 

The movement of the actuating lever on the box looks ok, although I have yet to try disconnecting the cable and operating it by hand. The box has done approx 470 engine hours from new.

 

Anyone have any ideas? The only thing I could come up with was cable stretch, as reverse is the "pull" direction.

 

Andrew

[eightpot]

Could be cable stretch. IIRC the "throw" of the actuator arm should be 35 degrees from neutral in both directions.

[pete.i]

Hi

it could be cable stretch or the cable out of adjustment. Both of those adjustments should be faily simple to carry out.

 

http://www.bukh-bremen.de/files/346/upload/Hersteller/ZF/Reparaturanleitung%20u%20Ersatzteilliste%20ZF3M%20bis%20ZF30M%20mechanisch.pdf

 

That is a link to the manual for that (and other) Hurth gearboxes. I haven't looked all through it but I'm sure the measurements you need are in there. I had a similar problem with my Hurth ZF 10 gearbox although mine was in forward. I did all the settings from that manual to no avail. My problem was the clutches. These are replaceable and the bits and pieces are available from ASAP supplies. My problem was that when I got the gearbox apart the bearings needed replacing as well and it. apparently, needed new shims. Also that sort of work was way beyond my capabilities and also the cost of the bits was nearing £300 so I eventually bought a recon unit off Ebay for £350 and fitted that. One day when I can be bothered I might resurrect my old box and have another go.

 

Hope that helps.

 

Pete

 

Forgot to mention that your symptoms sound almost the same as mine. My gearbox would sometimes not engage immediately and would drop in and out of gear for the first 15 minutes or so of cruising. After that it was fine untill the following day, presumably, after it had cooled down.

Edited December 26, 2013 by pete.i

[AndrewIC]

Thanks, I'll take a look. Once in reverse gear it stays in gear. I think I'll try disconnecting the cable in the morning and see if it operates consistently by hand. I hope it's not he box

[AndrewIC]

Disconnected the cable and operated it by hand - same result Checked the cable travel and any slack - all correct :(

 

Not very impressed with the lifespan of this box - the HBW100 it replaced had done ~3000 hours before it gave up the ghost. That one was beyond economic repair!

[pete.i]

Yes the longevity of Hurth boxes is, apparently, not good. having said that my original one was replaced back in the nineties I think and has been okay until my second year of owning the boat. Things like not wanging it back and forth between forward and reverse, and no I am not suggesting that is what you did, and changing the ATF on a more than recomended basis are things that people say will prolong the life of these boxes. They do like to run cool and some ATFs are not recomended for these boxes. In fact Hurth, or whoevefr owns the company now, only recomend one automatic transmission fluid for that particular box. Of course that is the most expensive and the most difficult to obtain. I did manage to get some for my box of EBay. There are some useful maintenance tips here:-

 

 

 

also the name of the ATF that is, in their opinion, the best to use and why.

 

Hope that helps.

 

Pete

 

Had to edit that because it lost the copy and pasted link when I posted so I hope that link, which now isn't a live link, works.

http://www.foleyengines.com/resources/tech-tips/zfhurth-marine-transmissions-six-step-program

 

HHMM okay must be me LOL. further edit to add the correct working link.

Edited December 27, 2013 by pete.i

[BEngo]

Might be worth a chat with Richard of Primrose Engineering - RLWP on this forum. He seems to be quite good with gearboxes. Lots of how it works and what's inside various gearboxes on the Primrose Engineering site.

 

N

[AndrewIC]

Thanks, I'll have a dig when I'm back home on a proper internet connection. I also see that ASAP stock the ZF-10M "as a replacement only", and "strongly recommend" PRM for new installations.