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[Junpu]

I need to replace the Hurth HB50 transmission on my ’86 Catalina 34 Mk I. Catalina Direct offers a ZF 12M transmission and calls it a “very close replacement” to the Hurth HB50. The ZF transmission is slightly larger than the Hurth. It’s 37mm longer and requires the engine to be raised 10mm. Raising the engine 10mm won’t be a problem, but I’m concerned about the addition length. Although Catalina Direct won’t guarantee that the ZF will fit my C34, they said that it “should” fit.

Has anyone replaced an original Hurth HB50 transmission with a ZF 12M on a Catalina 34? Also, I’ve heard the PRM 60 transmission is another “drop in” possibility for the Catalina 34. Any thoughts?

[KWKloeber]

@J

I don’t know which engine you have, but this thread discusses both the ZF and PRM.
Note the explanation how a new shift bracket is needed.

https://groups.io/g/Catalina30/topic/81005942?p=,,,50,0,0,0::Created,,Transmission,50,2,0,81005942

[Ron Hill]

Jun: I replaced my old Hurth 50 with a Hurth 100 .  I believe that the ZF 12 and the Hurth 100 have the same outside case. 
I believe that I cut about 1.5" to shorten the shaft.  But then I had a Vetus flex coupling so the keyway loss made no difference.

Hope this helps   A few thoughts