Transmission slippage on a Catalina 28 mark 11?

Sep 18, 2019
2
Catalina Catalina 28 mark II Brockville
I own a 2004 Catalina 28 mark 11 second year of ownership. This year I've experience , what I believe to be forward gear "slippage" I have a M 25XPB with a Hurth ZF 5 M transmission. When I back out of my slip and then go forward , any throttle other than idle speed seems to disengage forward. I have to reduce throttle put in neutral and try again. I've replaced transmission fluid, (it was reddish brown). I've read where allot of Catalina 30 owners had issues with Hurth transmissions. My mechanic friend asked me to check the cables and they appear to be fully functional (all the way back for forward and all the way frontwards for reverse). I've been asking other club members and so far the census is worn clutch plates. I'm to remove and sand them if they are too smooth.
any suggestions? anyone else have this issue?
 
Feb 8, 2014
1,300
Columbia 36 Muskegon
The Hurth gear boxes are prone to slipping when the clutch plates wear. A poor design. It needs rebuilding, but the rebuild kits are hard to find and expensive, somewhere around $500, of you can find one. If you rebuild it, you'll eventually have to do it again.
I recently replaced my HBW5 with a Newage PRM 60D. It's a nearly drop in replacement, the only difference is the shift lever is on the other side and goes forward for forward instead of aft for forward. You can reverse the shift lever direction at the trans if you can't do it in your control lever. Mounting interface and shaft coupling are identical. Uses cone clutches like the Kanzaki on a Yanmar. Much more robust and reliable. Cost was only about $600 from ASAP Supply in the UK. The only adaptation I needed to do was fab a new cable bracket, and that was just a piece of 1/4" steel with some holes drilled in it. I've got probably 100 hours of pretty heavy use on it, and it's preformed flawlessly.
 
Sep 18, 2019
2
Catalina Catalina 28 mark II Brockville
The Hurth gear boxes are prone to slipping when the clutch plates wear. A poor design. It needs rebuilding, but the rebuild kits are hard to find and expensive, somewhere around $500, of you can find one. If you rebuild it, you'll eventually have to do it again.
I recently replaced my HBW5 with a Newage PRM 60D. It's a nearly drop in replacement, the only difference is the shift lever is on the other side and goes forward for forward instead of aft for forward. You can reverse the shift lever direction at the trans if you can't do it in your control lever. Mounting interface and shaft coupling are identical. Uses cone clutches like the Kanzaki on a Yanmar. Much more robust and reliable. Cost was only about $600 from ASAP Supply in the UK. The only adaptation I needed to do was fab a new cable bracket, and that was just a piece of 1/4" steel with some holes drilled in it. I've got probably 100 hours of pretty heavy use on it, and it's preformed flawlessly.
Yes I've heard that most Catalina 30 owners are replacing their transmission's with the PRM60. Thanks for confirming my suspicions.
 
Jul 7, 2004
8,402
Hunter 30T Cheney, KS
I thought "slippage" is only caused by the clutch between the flywheel and the propshaft fitting. Not internally. My Kamakazi on my Hunter is this way. I had to pull everything once to replace the tooth ring on the flywheel. Are the Hurths different?
 
Feb 8, 2014
1,300
Columbia 36 Muskegon
They are different. Disc clutches rely on manual pressure to hold the plates together. As the plates wear the system no longer supplies enough pressure and they slip. Cone clutches like in the Kanzaki or PRM pull themselves together when they are engaged. (Very simplified description.) The more power transmitted the harder they pull together. Takes a lot more wear to open the tolerances to make them slip. Probably the engine would be worn out before this happens.
 
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