Upgrading Transmission to ZF10

[lbertran]

Our 2003 ZF5 transmission with only 400 hours on it is slipping in Forward gear. Suddenly, there are metal particles in the transmission fluid. Our mechanic is advising the removal and disassembly of the transmission to see whether a rebuild makes sense or whether we need a new one. I did a search on this site yesterday that turned up some folks that feel the ZF5 is not beefy enough for a Universal M-25XPB. Some of you have upgraded to the ZF10. I'm thinking that if I have to pay for removal and reinstall of my transmission anyway, it might make sense to save the rebuild dollars and invest in the beefier ZF10. I have a question for folks who have done this upgrade, were any modifications necessary to accomodate the larger ZF10? Thanks!

 

[mherrcat]

I have been investigating this as well, and from what I can tell from the documentation on the ZF website, the ZF5M (discontinued), ZF6M and ZF10M all have the same dimensions. Unless I am missing something...

The ZF6M and ZF10M can both be had for basically the same price.

Actually, just spoke to someone at MER Equipment about this and it turns out that the ZF5M/HBW50 is slightly smaller than the 6M and 10M which are both the same size. The difference in the distance between the input and output shafts of the 5M and 6M/10M is about 1/8" and the total length of the 6M/10M units is about 1/4" longer. So the engine would have to be raised 1/8" and the prop shaft moved back 1/4". But that all seems like it would be within the adjustment range of the engine and the shaft.

I think the ZF6M is also being discontinued in favor of the ZF10M.

 

[mherrcat]

Just did some more checking and it seems like the length is actually 1" longer for the 6M/10M and the dimension from the center of the shaft to the outside of the shift lever is +3mm.

All of this can be found online by searching for "ZF5M marine transmission" or "ZF marine transmissions"

 

[Rocinante33]

I did this mod

You are correct. The ZF10 is about 1" longer than the HBW50 (ZF5). Therefore, you lose an inch of open prop shaft. On mine, I will have to pull the prop shaft next time the boat is hauled and will cut the prop log shorter by an inch or two. I cannot slide the packing gland up far enough to change the packing as it is now with the new ZF10. That is the main modification required in this swap. Other than that, just motor mount adjustment to re-align the engine/trans to the propshaft. See my earlier post about it. I did the swap with the boat in the water, but it was not easy. Good luck!

 

[Captron]

Trans swap

I did the swap on Kismet our E-38 with a Universal 5432.

In order to provide clearance for the new ZF-10, the mechanic had to move the engine forward 3/4 of an inch.

This required modification of the forward engine bunk and moving the Racor fuel filter which had been mounted on the starboard engine compartment bulkhead. It fits but just barely. I have a PSS Shaft Seal on my E-38 also. This means that I might have about an inch of exposed shaft showing.

I also added the gearbox cooling apparatus but it fits on the port side of the trans and doesn't take up much room.

I'm not real happy about the notch taken out of the forward engine bunk but I wasn't there when it was done so I didn't have any choice in the matter. The old Racor fuel filter did not conform to ABYC specs so moving it out of the engine compartment made good sense. It's now in the starboard lazzarette and is more accessible there anyway.

By the way, moving the engine forward that much did not cause any cabinet changes although everything JUST clears including the K&N air filter I have on the intake.

All things considered, if I was doing it myself, I would have likely used the smaller tranny with the cooler option. It probably would have only saved a couple of hundred bucks on a $4500 job.

On the other hand this installation works fine so what am I complaining about? It's only the engine anyway.

 

[lbertran]

Thanks to All

My plan to upgrade to a ZF10 transmission was nearly derailed by the fact that these transmissions are on a nationwide backorder with an optimistic delivery date of late October and possibly later. I should say that while I would have had to sacrifice the remainder of this sailing season, I would have been willing to wait for the ZF10 rather than rebuild my ZF5. But after a nationwide search for a ZF10, my mechanic located one today. We'll need a short haul to modify the shaft but are hopeful that we'll be back to sailing our boat in a week or two. Thanks to all for the helpful info.

 

[Dan Morehouse]

Interesting. My mechanic told me the same thing about ZF10 transmissions being on back order til October. Then he told me the ZF15 was actually a more proper replacement for the HBW100 that just failed in my boat. It's also about $400 more than the ZF10. And an e-mail exchange I had with someone at ZF suggested that the ZF15 has less of a dimensional difference from my old tranny than the ZF10, which didn't make much sense. I'm going to bite the bullet and install the ZF15. Being a heavier unit appears to negate the need for a cooler option. Incidentally, my current junk transmission was a rebuilt unit installed by the previous owner, who had the work done at a yard in San Diego. That was only four years and less than 500 engine hours ago. I'm not impressed.

Dan Morehouse
1981 E-38 "Next Exit"

 

[Dan Morehouse]

My transmission replacement is now complete. I had the mechanic replace the bad one with a ZF15. He did it with the boat in the water and was able to get the old one out and the new one in without even moving the engine...and the alignment was perfect. After all I've read, that surprised me. This ZF15 turned out to be virtually a carbon copy of the original. And we tested it by finishing the delivery to SF from Morro Bay, a total of about 40 hours of motoring. No excess vibrations or other problems. Murphy must have been on vacation. Total job cost just under $3000.00.

Dan Morehouse
1981 E-38 "Next Exit"