Transmission replacement

kh3412 · October 26, 2018, 11:16:34 AM

Well the next winter project is here. A little something I picked up at the boat show.

Ron Hill · October 26, 2018, 03:01:26 PM

kh34 : Depending on which engine you have and which transmission it is - is directly proportional to how difficult your winter project is!!!!

A Big Thought

kh3412 · October 26, 2018, 05:06:04 PM

Ron that's not nice ruining my day. How hard could it be to pull the engine, take the bellhousing off, disconnect the transmission. Then find the motor stringers are wet, the motor mounts are worn, the prop shaft has a groove by the seal, what could go wrong. Oh yeah I forgot about getting grease all over the Admirals galley.
It looks like it will be a big project, but it is a long winter and will make me trust taking the boat out of the dock without hitting my dockmates.
With this site and all the help that has gone down this path already it WILL be ok. (I Hope)

But feel free to Rain on My Parade I got a new transmission today.

Jim Hardesty · October 27, 2018, 05:41:46 AM

QuoteHow hard could it be to pull the engine, take the bellhousing off, disconnect the transmission. Then find the motor stringers are wet, the motor mounts are worn, the prop shaft has a groove by the seal, what could go wrong

Kudos on you excellent attitude.
Jim

Phil Spicer · October 27, 2018, 05:55:39 AM

I'm still at Deep Water if you ever need an extra hand.

Stu Jackson · October 27, 2018, 10:56:03 AM

Congratulations on your "find." You most like have an M25XP in your boat. Care to share the make and model number of your new "toy?"

All the best during your installation.

Ron Hill · October 27, 2018, 01:11:52 PM

kh34 : I'm not trying to "rain on anybody's parade". I would point out that if you mentioned your Hull # or your engine model and the transmission model - the readers of this message board could give you some tips!!
You mentioned some of the things that you will run into. Just mentioning that you have to remove the "Bell housing" tells me that you probably have an M25 or a M25XP engine??
I might add to your list of things - that if your new transmission is a ZF 10 (Hurth 100) you are going to have to shorten your drive shaft. You might also want a new damper plate and with the engine removed you might also consider some new sound insolation.

I hope you read some of my Mainsheet articles, as I removed the old engine twice for repair and then removed it for a M25XPB replacement.

A few thoughts

Bill Shreeves · October 27, 2018, 02:39:57 PM

Congrats! Nothing like new equipment. I replaced my ZF5 with a ZF10 Spring of 2017 on my '87 C34. Make sure you compare the new gearbox length and shaft offset to know what you might be up against regarding the geometry. BTW, I didn't need to remove the engine or the bell housing. Be sure to replace your damper plate while in there. Its removable with the bell housing in place. Still have the ZF5 in my basement of anyone else is interested, needs a rebuild....

kh3412 · October 27, 2018, 04:28:58 PM

Ok
First, Ron take no offense at my warped sense of humor.
Second, yes I have a M25XP
Third, boat is a 1988 hull#618
Forth, the new trans is a TwinDisc TMC 40p, 2.00-1 ratio the ratio was picked by working from the prop back so the ratio fits the prop to desired engine speed, with an eye to boat weight.
Fifth, new damper plate is in the box as well as a flex coupler who's name I can't recall at this time.
Finally, I appreciate all the knowledge from this site. This is the greatest asset in having a c34

Just got back from tenting it up for the winter not sure if I will start this year or wait for spring.

kh3412 · April 07, 2019, 06:00:32 PM

Well the weather is getting better so I started the process of replacing the transmission. Pulled the floor out of the galley so I would have someplace to set the motor. Disconnected hoses and wires removed exhaust and cables. Set a beam across the companionway and pulled the motor forward into the galley. Shaft was already disconnected so as to size for replacement. Removed bell housing from engine, transmission from bell housing and used bell housing with new transmission to fit where I would need to trim engine stringer. Had to trim about 3/4 of an inch about 3 inch from rear port stringer.

Bobg · April 08, 2019, 06:58:41 AM

Going to love following your project, Just curious, but why did you feel like you had to change your transmission, was it slipping? or clunking or leaking?

kh3412 · April 08, 2019, 08:34:20 AM

The reason was:
1. Peace of mind. The hurth transmission has a history of failure
2. Starting to slip in forward
3. Unknown hours or maintenance on this unit.
4. The price vs repair favored the twin disk, and we use twin disk PTO's at work and have few problems.

pablosgirl · April 12, 2019, 04:55:22 PM

KH3412,
I have an 88 with the M25XP also, where did you buy the flex plate from? I have a noisy output shaft bearing and this is in my future. I suspect when the PO had the cutlass bearing replaced that they used a slide hammer to take the prop and shaft out and hence damaged the bearing. No slippage in forward though just a little noisy.

kh3412 · April 12, 2019, 05:31:29 PM

The flex plate came from beta marine Stanley over there is super to work with. Don't have a number as it all came together with tranny and flexible coupling.

kh3412 · April 12, 2019, 06:13:17 PM

Cleaned up the bell housing and drilled a new hole for the Port rear motor mount. This is the mount that is right by the shifter and cut out I made in the engine support stringer. As my supports are narrow and the outside holes on the bell housing are to far out I added a hole in between them. This still put the mount over the center part of the support but moves it forward a few inches. Also started working through the shift linkage. The linkage will be pointing down so as the shifter on the pedestal operates as it has in the past. Did not want to go through a learning curve over which way a move the lever to go forward or reverse.