Remove and Replace Z10 with Z12 Transmission

[Luana]

Good Afternoon, it appears that I have been forced into the ZF 10 transmission breakdown group.  SV Graylin is a 2004 Catalina 34 Mk2. It has an M35B Universal engine.   I understand that the new replacement ZF 12 is a more robust transmission.  I am wondering if anyone has changed out the Z10 with the Z12 with the same engine as Graylin.

I have reviewed many of the Message Board comments but can't seem to find the same Catalina Model and engine combo for the Z12. From the internet it seems that there may be a need to raise the engine.  The Z12 is a somewhat larger transmission and I am wondering if I will need to shorten the shaft to accommodate the larger transmission or if there will be sufficient room. The gear ratio seems to be a bit different and wonder if a new prop would be required in the process.  At the moment, it seems that the transmission can be pulled without pulling the engine but not certain.

I contacted the Beta Dealer in Victoria BC thinking that they may have a transmission that would work.  He was confident that any of their transmissions would require "a lot" of adapting and suggested the ZF12 might be the best bet. 

Has anyone swapped out these transmissions on a M35B?  I would be most interested in your thoughts/ideas. Many, many thanks.

Rod MacDonald

[Breakin Away]

I'm going to sound like a broken record here, but you've outlined the reasons why you would be much, much, MUCH better off rebuilding your current transmission. The PO of my boat had it rebuilt about a year before I bought it (would have been sometime around 2015), and I am so glad he did. From what I recall of the repair records, it looks like it was removed without having to remove the engine.

I know that the original Hurth transmission has been discontinued, but not sure whether the rebuild parts have been discontinued. Hopefully a good transmission shop would know of alternate parts if needed.

Just a question: You didn't put synthetic ATF into it, did you? If so, and you're having severe slipping, you might have an easier fix available to you.

[Breakin Away]

Quick comment: I did some searching. There are rebuild kits available for ZF10M/HBW100. There are various kits depending on how comprehensive the rebuild needs to be. So it does appear to be an option for you.

Like I said before, if you are experiencing slipping, have a close look at your transmission fluid to make sure it is the right stuff. My transmission was slipping during my first year of ownership, which I couldn't understand since it had just been rebuilt a year ago. I changed the fluid annually with the proper DexronIII fluid, and it gradually got better over a few years. Now, 7 years later, it works perfectly. I don't know what PO had put into the transmission, but in retrospect I suspect it may have been synthetic ATF, which is known to cause slippage. Presumably it took a few refills to fully eliminate any adsorbed traces of it from the interior surfaces. If you are having slipping problems and suspect you have synthetic ATF, I'd suggest a few refills with the correct Dexron fluid, with a few hours of use in between each refill. Much cheaper and easier than a rebuild or replacement.

[pbyrne]

Quick comment: I did some searching. There are rebuild kits available for ZF10M/HBW100. There are various kits depending on how comprehensive the rebuild needs to be. So it does appear to be an option for you.

Like I said before, if you are experiencing slipping, have a close look at your transmission fluid to make sure it is the right stuff. My transmission was slipping during my first year of ownership, which I couldn't understand since it had just been rebuilt a year ago. I changed the fluid annually with the proper DexronIII fluid, and it gradually got better over a few years. Now, 7 years later, it works perfectly. I don't know what PO had put into the transmission, but in retrospect I suspect it may have been synthetic ATF, which is known to cause slippage. Presumably it took a few refills to fully eliminate any adsorbed traces of it from the interior surfaces. If you are having slipping problems and suspect you have synthetic ATF, I'd suggest a few refills with the correct Dexron fluid, with a few hours of use in between each refill. Much cheaper and easier than a rebuild or replacement.

I don't have this issue, but this is a great tip.   

BTW, what is the recommended ATF, and is there a particular brand that people favour?

To the OP, having been upside down a lot in that compartment lately, (with the bruises to show for it) I have my fingers crossed for you that a fluid change will sort out the issue.

[Luana]

Quick comment: I did some searching. There are rebuild kits available for ZF10M/HBW100. There are various kits depending on how comprehensive the rebuild needs to be. So it does appear to be an option for you.

Like I said before, if you are experiencing slipping, have a close look at your transmission fluid to make sure it is the right stuff. My transmission was slipping during my first year of ownership, which I couldn't understand since it had just been rebuilt a year ago. I changed the fluid annually with the proper DexronIII fluid, and it gradually got better over a few years. Now, 7 years later, it works perfectly. I don't know what PO had put into the transmission, but in retrospect I suspect it may have been synthetic ATF, which is known to cause slippage. Presumably it took a few refills to fully eliminate any adsorbed traces of it from the interior surfaces. If you are having slipping problems and suspect you have synthetic ATF, I'd suggest a few refills with the correct Dexron fluid, with a few hours of use in between each refill. Much cheaper and easier than a rebuild or replacement.

I'm going to sound like a broken record here, but you've outlined the reasons why you would be much, much, MUCH better off rebuilding your current transmission. The PO of my boat had it rebuilt about a year before I bought it (would have been sometime around 2015), and I am so glad he did. From what I recall of the repair records, it looks like it was removed without having to remove the engine.

I know that the original Hurth transmission has been discontinued, but not sure whether the rebuild parts have been discontinued. Hopefully a good transmission shop would know of alternate parts if needed.

Just a question: You didn't put synthetic ATF into it, did you? If so, and you're having severe slipping, you might have an easier fix available to you.

Thanks for your response.  No, I have not used synthetic ATF.  You are correct about the availability of rebuild kits for the ZF 10.  I have contacted one marine shop and a transmission shop, both are willing to inspect and rebuild, once the transmission has been removed - which hopefully will be on Monday.  I am nervous about rebuilding the ZF 10. I have heard many comments that the rebuild kits may not be of the same 'quality'.

In my ongoing investigation of alternate transmissions I came across one called Technodrive TMC 40P.  This has been used for years in Beta engines.  Before knowing about this transmission, I called the Beta dealer in Sidney and he claimed that he didn't have any transmissions in the lineup that would fit my situation. However, this transmission is reported to be a very simple change out with minimum modifications.  I have specs for both the Technodrive and the ZF 10 and the main difference is about 4-5 mm in transmission length, (the Technodrive being longer.)   My neighbor replaced his ZF 5 with the same Technodrive transmission in his 25 HP Catalina 30 a few years ago and he claims it is a smooth and robust replacement. 

I am currently searching for this particular transmission.  I will contact the Beta dealer again on Monday to see if he has one available.  If he doesn't, I may have to purchase it state side, if it appears to be as good as the claims.  If anyone  has heard reports on these transmission, I would appreciate any feedback.

Thanks again Breaking Away for your comments.