Direct Replacement for ZF 25 MA tranmission

[TrailerCruiser]

I'm wondering if there is direct replacement for a ZF 25 MA transmission that doesn't need a bunch of engineering changes, like shaft length, or engine angle. I have a ZF 25 MA that is slipping, but not sure I want to shell out $2200 for one. I'm just wonder if there is a cheaper replacement. Note I have a westerbeke W 70 (70 hp). Note the ZF 25 MA has a 8 degrees down angle.

[FPNC]

With your engine and application, your at the upper margin for the capacity of the 25MA. My advice is that you move up to the ZF 25A hydraulic, or the Twin Disc MG5005A or the Technodrive TM345a. All of these are similar in geometry to the 25MA. You will not find a 'drop in replacement' for the 25MA.

[TrailerCruiser]

Thank you for the other transmission options that have a 8 degree down angle. Do you happen to know how much re-engineering it will take to put one of these transmissions in. What will it take to bolt these to the back of the Westerbeke W70? Currently the ZF 25 MA has 6 bolts to attach to the motor. I also assume a new arm to attach the shifter cable will be necessary as well. Trying to assess whether a different transmission makes sence, because my old ZF 25 MA didn't seem to last that long, plus it take 3 to 4 months to get one and seem like a lot of money.

[FPNC]

The 25A will have the same input spline and output flange as the 25MA. The face bolt up is the same. It will have about 5 mm more offset so the engine will need to be raised up. It will be about 6 mm shorter fore and aft so the shaft will need to come forward or the engine will need to go aft. Being within 5-6 mm of the original transmission is as good as it gets.

You will need to add an oil cooler. The current 25 MA should have had the block cooler installed but may not. You will need a single pass oil cooler and hoses to connect to the transmission. The shift bracket can be purchased or made of flat bar to fit your engine space. The hydraulic gear shifts much easier than the mechanical.

Be aware that the case size is physically larger. Make sure you have the space. This transmission is more expensive than the 25MA mechanical box. Mainly because it is rated for your engine hp and application. Properly installed, you will not be replacing it anytime soon. Replace your drive plate if it is not like new.

[JDanielBryant]

An option that is cheaper than $2200 is simply buying the rebuild kit (seals, plates and discs) on EBay for about $250 and rebuilding it. You could even just bring both to an auto transmission and have them do the work for a couple hundred. I did mine last year but ended up needing a tranny shop’s gear press to reassemble the primary shaft. Marine transmissions are pretty simple compared to what they are used to...

[TrailerCruiser]

Originally Posted by FPNC

The 25A will have the same input spline and output flange as the 25MA. The face bolt up is the same. It will have about 5 mm more offset so the engine will need to be raised up. It will be about 6 mm shorter fore and aft so the shaft will need to come forward or the engine will need to go aft. Being within 5-6 mm of the original transmission is as good as it gets.

You will need to add an oil cooler. The current 25 MA should have had the block cooler installed but may not. You will need a single pass oil cooler and hoses to connect to the transmission. The shift bracket can be purchased or made of flat bar to fit your engine space. The hydraulic gear shifts much easier than the mechanical.

Be aware that the case size is physically larger. Make sure you have the space. This transmission is more expensive than the 25MA mechanical box. Mainly because it is rated for your engine hp and application. Properly installed, you will not be replacing it anytime soon. Replace your drive plate if it is not like new.

My 25MA isn't plumbed for an oil cooler. If my 25MA didn't have an oil cooler could I go without an oil cooler for this new one?

[TrailerCruiser]

Originally Posted by JDanielBryant

An option that is cheaper than $2200 is simply buying the rebuild kit (seals, plates and discs) on EBay for about $250 and rebuilding it. You could even just bring both to an auto transmission and have them do the work for a couple hundred. I did mine last year but ended up needing a tranny shop’s gear press to reassemble the primary shaft. Marine transmissions are pretty simple compared to what they are used to...

I haven't been able to find anything that cheap. I'm looking for the parts for the clutch and I see there is a clutch and seal kit but it around $1000.

[TrailerCruiser]

Originally Posted by FPNC

The 25A will have the same input spline and output flange as the 25MA. The face bolt up is the same. It will have about 5 mm more offset so the engine will need to be raised up. It will be about 6 mm shorter fore and aft so the shaft will need to come forward or the engine will need to go aft. Being within 5-6 mm of the original transmission is as good as it gets.

You will need to add an oil cooler. The current 25 MA should have had the block cooler installed but may not. You will need a single pass oil cooler and hoses to connect to the transmission. The shift bracket can be purchased or made of flat bar to fit your engine space. The hydraulic gear shifts much easier than the mechanical.

Be aware that the case size is physically larger. Make sure you have the space. This transmission is more expensive than the 25MA mechanical box. Mainly because it is rated for your engine hp and application. Properly installed, you will not be replacing it anytime soon. Replace your drive plate if it is not like new.

I just looked at the specs for the ZF 25 A. I see it has seems to have the bell housing attached. My ZF 25 A doesn't have a bell housing. It is bolted to the engine with the six bolts shown on the diagram with B1 and B2 found here: https://www.performancediesel.com/wp-content/uploads/ZF25MA.pdf. Does the bell housing on the ZF 25 A bolt to a flange on the back of the transmission with a 6 hole bolt pattern?

[FPNC]

Your W70 in a displacement vessel application is over powering your ZF 25MA.

The case cooler for the ZF 25MA does help keep the lube oil cooler and would be a required specification by ZF but frankly the difference would be pretty marginal.

The ZF 25A would absolutely require an oil cooler. No exception.

The ZF 25MA and the ZF 25A do not come standard with a 'bellhousing/adapter plate'. This is a bolt on item and sometimes not required. There are numerous different adapter plates that fit these transmissions.

Both the ZF 25MA and the ZF 25A have the same bolt up pattern. It is a 6 bolt pattern on the input face of the gear.