[C320-list] Hurth HBW50 transmission problem (and solution)

[Doug Treff]

Frank,

This is great information, and thanks for sharing. Maybe you've just saved some other person from the same scare later on when they search our email archive.

Thanks,

--
Doug Treff
doug at treff.us

On Thu, Nov 5, 2020, at 9:55 AM, P.F. Ross wrote:
> I don't recall seeing this issue on the discussion list but thought I would
> post it in case it happens to anyone else.
> 
> Thanks to current travel difficulties, we were far away from our boat and
> it sat in the water unused for about 7 months.  Now back at the boat, I
> went through my typical engine recommissioning tasks and let the engine
> warm up in Neutral.
> 
> To check the drivetrain (boat was still tied to my dock), I shifted into
> Fwd (engine at idle) and the engine immediately died.  I had already
> checked the freedom of the prop shaft, but shifted back to N and checked
> again, still free.
> 
> Checked tranny oil level, color and smell, all good.
> 
> A couple of more attempts and the same thing happened.  Tried Rev and same
> thing.  It was obvious that the engine was being dragged down when tranny
> was shifted into gear.
> 
> I tried again, this time slightly advancing throttle when tranny was
> shifted.  I was able to keep the engine running slowly but now under
> extreme labor.  Quickly shut down engine.
> 
> Checking the discussion list, I was looking at tranny rebuilds or
> replacements for mucho $$$.  Well, darn (ok, worse).  There were several
> online discussions on who to call, with mixed reviews.  One suggestion was
> to call ZF (Hurth owner) directly so that is where I started.
> 
> My experience is mixed when calling large companies for help, but I cannot
> say enough about Juan at ZF USA headquarters in Miramar, FL (direct line
> 954-441-4026).  He listened patiently to my situation and strongly
> suggested that I was not getting enough travel on the Fwd-N-Rev actuating
> lever on the side of the tranny case.  He advised to remove the actuating
> cable and check.
> 
> The owners manual and overhaul manual (both on the 320 website) describe
> minimum +/- 30 mm travel from N when measured at the lower hole (where my
> cable attached).  While this measurement is kind of unwieldy, it is very
> easy to feel the detents when operating the lever manually with the cable
> disconnected.  Overtravel of the lever in either direction is not a problem
> (according to manuals), but you need to make sure you are at least passing
> the detents in both directions.
> 
> It was easy to make sure my actuating cable was free once it was
> disconnected since I was able to push and pull the cable from the engine
> compartment.  I made one very slight adjustment on the cable end threaded
> pin to make sure I had plenty of Rev stroke (it seemed to be biased toward
> Fwd) and reassembled.
> 
> Voila!  All is well and it now shifts normally.  I am not sure what, if
> anything, the long slumber of my boat had to do with the problem, but my
> thinking is that the manual exercising that I did to the tranny lever when
> disconnected from the cable did the trick.
> 
> Hopefully I did not do any damage to the tranny when operating in the
> half-actuated positions, but it does not seem like I did at least so far.
> But it cannot be a good situation and one that it easily fixed, at least
> for me.
> 
> Frank Ross
> "Beta Wave" #206
> Naples, FL
>