[C320-list] Hurth to ZF10 replacement

[Warren Updike]

I considered this a few years ago vs rebuilding the Hurth. As I recall, the ZF10 is slightly longer fore/aft than the Hurth with the Perkins engine. The choice was then replace or adjust the shaft; or, live with the shaft further extended between the strut and prop. As a rule-of-thumb, the space between the strut and prop should not exceed 150% of the shaft diameter (1.5in for our 1 inch shaft.)

If you want the ZF10, you might consider cutting the shaft to accommodate the longer length, replace the cutlass bearing, and install a new flex coupling. The flex coupling will dampen vibration and tolerate mis-alignment better on the assumption you can never have a "perfect" alignment. You might also consider replacing the shaft with stainless steel (check the archives for more on that.)

As I stayed with the Hurth and had it rebuilt by a Hurth certified shop near Annapolis, I have been very happy since. Rebuild was about half the cost of a new tranny. 

Warren and Pattie Updike
1994 C320 "Warr de Mar" #62

-----Original Message-----
From: Brian Behler [mailto:bbehler at yahoo.com] 
Sent: Monday, July 13, 2015 11:17 PM
To: c320-list at lists.catalina320.com
Subject: [C320-list] Hurth to ZF10 replacement

Hello
Our Hurth HDW50 has ceased operating and I have a ZF10 ordered and on the way.  My question is whether anyone has done a replacement without hauling the boat.  We are in North Idaho and services are very limited.  We have Hull #166 Simpatica and the engine/tranny had but 800 hours.  I am not planning on replacing the cutlass bearing as no unusual shaft play or vibration.
Thanks for the help fellow members
Brian BehlerSimpatica 166