Transmission Replacement

[Bill Shreeves]

So... my, new to me last Spring, 1987 34 appears to need the transmission "fixed" and I would like the opinion from those that know more about this than I do which, probably includes everyone that's a member of this great org...  I say that because this is my first boat since I sold my 16' Hobie 30+ years ago so, I have much to learn.  I've sailed occassionally with others and been on a 2 week cruise on a Gulfstar 52 in the Abacos 25 years ago and a 2 week cruise in the Virgin Islands on a Hunter 42 15 years ago so, the love of sailing has always been there.  Just needed the time and resources to get one of my own.

Following paragraph is the lengthy background.  To get to the question, skip to the next paragraph 

The boat was re-powered 10 years ago by a PO with a M25XPB / ZF5M transmission.  I bought it with 450 hours on it.  Yes, had it inspected and nothing reported about the tranny.  Not having any previous experience as an owner/skipper, I didn't notice that the "feel" when shifting in to fwd was different than rev. Kind of slide in to fwd, firm engagement when going to rev.  That came to mind when I wondered why it didn't begin to move fwd when I shifted to fwd after backing out of my slip mid-season a couple times.  I began to do some research and looking and I believe the tranny is toast or nearly toast or the following reasons.  A big oversight on my part was not checking tranny fluid right after buying.   I did the oil, fuel filters and everything I could think of for the engine but neglected the tranny.  Well, when I checked, no evidence that the fluid had ever been changed.  Factory paint undisturbed.  Checked dip stick and no fluid.  Drained and found thick burnt fluid to no surprise.   I filled with new fluid, ran to get to get it warm, shifted a few times then changed again.  Tranny shifts a little better but, I don't think I can trust it.  I'm open opinions on this.

So, my research shows it'll be little savings to rebuild the ZF5 and likely far better to go with a brand new ZF10M, if I can get one since they are recently discontinued, or go with a ZF12M.  I'm not going by the inflated price for the 10 on CatalinaDirect.  I'm inclined to go with a 12 but the ratio gives me pause.  Going from 2.05 to 2.14.  Am I making much ado about nothing?  BTW, I'm aware the 10 is about an inch longer than the 5 and the 12 about 1-1/2 inches longer than the 5 so, I'm assuming I should probably have the shaft shortened to accomodate either instead of asking more of the Cutlass bearing which also must be replaced while the boat is on the hard for the winter.


Thanks in advance to everyone for your input on this and for all the great info I've obatined from this group!!!

-Bill

[Stu Jackson]

Bill,

Welcome (again?)   

Good analysis.

Have you considered that it may only be the damper plate(s) that need to be replaced?

I know the C36 skippers have written up at lot on this, not so much here.  My recollection is that there are two damper plate replacements and one was found to be far superior to the other.  Let me know and I'll go look for links there. 

[Bill Shreeves]

Stu,
Thanks for the feeback.  An observation I made, but neglected to include earlier, indicates the tranny slips when put in to fwd.  I carefully watched the shaft while shifting between fwd & rev after I changed the fluid twice.   I was able to see, several times when shifting in to fwd, the shaft rpm would increase after a few seconds.  I would expect it to turn a constant speed immediately after shiftng in to fwd as it appears to when shifting in to rev.   It wasn't drastic but, definately notcable.  If it can be seen with the naked eye, I'm sure it would be significant with a tach.  So, I think this is an indicator that the clutch plates and or thrust bearing(s) are severly worn.  After what I've read about the 5M not being very durable if not well cared for, this would be no surprise if neglected like mine appears to have been.

I welcome your or others thoughts if there's some holes in my logic knowing I'm not a mechanic by trade and new to this.  I'm surely not trying talk myself in to a new tranny.  I'd much rather put that money elsewhere on her.

That been said, I'll read through what I can find on the 36 site on the Damper Plate since I plan on replacing mine.

[Noah]

I know absolutely nothing about transmissions, except thankfully mine still works, but a search for Hurth damper plates got me to this:
http://forums.sailboatowners.com/index.php?threads/very-distressed-transmission-and-damper-plate-failure.169509/

It may help?

[Ken Krawford]

There's a pretty good write up on damper plate replacement on the C350 web site - http://www.catalina350.com/phpBB3/viewtopic.php?f=11&t=685

There's also a pretty good write up on damper plate replacement on the C350 web site - http://www.catalina350.com/phpBB3/viewtopic.php?f=11&t=685


Bill,

Welcome (again?)   

Good analysis.

Have you considered that it may only be the damper plate(s) that need to be replaced?

I know the C36 skippers have written up at lot on this, not so much here.  My recollection is that there are two damper plate replacements and one was found to be far superior to the other.  Let me know and I'll go look for links there.

[Bill Shreeves]

Thanks for the links regarding damper plate replacement guys.  Lots of good infiormation and I'm now hopeful that my low RPM vibrations may be reduced after damper plate replacement but, I don't expect that to help with the slipping/engagement in to fwd problem.

I had assumed that I'd need to remove the bell housing to replace the damper plate but, now hoping I might be able to get it out after tranny and tranny mount adapter plate are removed from the bell housing on the 25xpb.

I've read some concerns over the R&D damper plate durabilty vs the Sachs but I don't recall any mention that the design was different.  Assuming there's an option to go with a high deflection R&D on a 25xpb, does anyone have any experience with this?

Also, any thoughts from anyone regarding the ZF10 vs the ZF12 as a replacement for my ZF5?   I know the gear ratio difference between 2.14 (zf12) vs 2.045 (zf10) which is nearly identical to 2.05 (zf5) so, zf12 will reduce my speed prop RPM by about 50 @ 2,500 engine RPM as compared to my zf5.  I'm assuming that reduction in SOG while cruising will not be noticable.

[Craig Illman]

Bill - Are you confident you're completely engaging it in forward? The stainless lever not hitting the binacle guard? (You hadn't mentioned checking the linkage) It seems that if it was the damper plate, you'd get the same symptoms in forward and reverse.

That said, your previous fluid state wasn't a good sign.

Craig

[Stu Jackson]

Bill,

I just ran across this topic this morning: http://www.cruisersforum.com/forums/f54/hurst-transmission-rebuild-177424.html

While he spelled Hurth wrong, it may be worth your time to do a search there on "Hurth" by "Maine Sail" and see what he had to say six years ago.  You may also find some good info on sources from the text.

You said you changed the fluid twice.  Did you fill the entire transmission up, as if planning on a winter layup, or just the small amount for normal use?  Consider filling it up once at least, may help.

[KWKloeber]

Bill

Re questions on plates etc, maybe talk to John Dillon (Marysville Marine / authorized ZF service center) @ (810) 364-7653.
Tell him Ken Kloeber / Weekend'R Products sent you (that might get you a cup of coffee.  LOL) 

If you do end up needing parts I may be able to get some discount off list.

Ken

[Bill Shreeves]

Stu - Thanks for the link.  I'll try and see what I can glean from your search suggestion.  Fluid change and final fill was to the recommended level for operation only.  I didin't think to fill to level for extended storage.  I only plan on being on the hard for 6 months ad they suggest 1 year plus for filling to the top.  I hope to have the tranny issue resolved before I commission her.

Craig - I shifted at the tranny and the lever was significantly farther than the 30 degrees, if I recall from the manual correctly, is needed.  I also had the Admiral confirm the shift lever on the pedestal had clearance.

Ken - Thanks!  I'll try calling them.  I got a price for a new ZF12 for $1,525 from someone in NJ and a rebuild of the 5 for nearly $1,500 because the OEM parts are really expensive now so, it's a no-brainer to go with new and one that is beefier.  I think the 12 price is really pretty good.   I haven't gotten serious about the Damper Plate yet but now starting to research that replacement as well.   I just don't see any value in not replacing it when I do the tranny work.

Also seriously thinking about a tranny cooler since one can be added to a 10 or 12.  Any suggestions?  I'm not even sure where you connect for cooling.  The heat exchanger?

[KWKloeber]

Bill do you know what was the ZF stock # of the quoted 12?   407206? 407205?

-kk

[Bill Shreeves]

Ken, I think the price was good for either however, it wasn't specified in the email.  I think the 407205 is for the A POS 2.136 fwd gear ratio and the 407206 is for the 2.632 forward gear ratio.  I need gear ratio 2.136.

[KWKloeber]

Bill

the 407206 is 2.63, but no matter.
That's a great deal out of NJ -- must be a ZF distributor -- that's just about $100 over dealer cost.

-ken

[sailaway]

The hurth transmission in forward it use clutch pads. In reverse its a direct lockup no clutch pads. My boat lost its clutch pads and had to back it home. rebuilt the tranny good as new. That is why when you sail the transmission should be in neutral or reverse. Charlie

[Bill Shreeves]

Ken, thanks for checking!  Can't complain about $100 over dealer cost.