A27 Sport/ Isuzu engine transmission replacement

[Mainer]

I have an A27 Sport with the Isuzu 6BD1 engine and Hurth HBW 360A transmission.

The transmission has failed and I have purchased a used ZF63A transmission without the mounting fixtures.

I've quickly determined that the old Hurth brackets that attach to the engine bed mounts are significantly different from what the ZF will require.

My question is:

Is there anyone on the forum who had this same engine and trans and replaced it with the same ZF and can advise how or where to acquire the proper brackets or specifications to adapt to the engine beds?

I have a good friend who is an excellent fabricator and can make new ones, but any help on specifications would be greatly appreciated.

Thanks in advance.

Dick Jones

[TorreyWP]

Sorry to see that we couldn't be much use in this matter Dick. Sometimes these custom jobs require the fabricator friend to take the project all the way.

I'm sure others (and myself included) are interest to hear how you are coming along.

Also, having spent several years apprenticing with a mechanic in the Portland area, I know there are many talented and creative technicians out there. If you interested in a local recommendation, I'm happy to supply one or two.

[Jay Knoll]

These guys may be able to help

https://www.sbmar.com/articles/marine-t ... ing-ideas/

[Mainer]

Torrey and Jay,

Many thanks for your replies. I sure felt alone out in the woods for some time with this project. Obviously this engine/trans combination is not all that common among members of the forum.

Here's the update: Torrey, you were right on with getting my friend to be the lead person and me as helper.

Because the old trans mounts had been holding the back of the engine up, upon removal we had loosened mounts and left the engine supported by 2x4's on either side of the bilge. After removing the engine bay doors, we used jack stands port and starboard and a stout pipe with come along to raise and hold the engine up.

Getting the ZF63A installed was a major effort. The ZF case is noticeably larger and my particular boat has a hard back with doors to the pilot house, so the bulkhead is right where the engine and trans meet - very difficult area. My friend and I worked on mating the trans for at least 3 hours before finally sliding the shaft into the engine. We then (after I was unsuccessful in getting any specs for brackets) started noodling on how to design new brackets. It was then that I discovered just how talented my friend is - he simply set about very carefully measuring everything, then took some pieces of thin plywood, my chop saw, a glue gun and amazing ingenuity, and fashioned a wooden template of the bracket he planned to fabricate. He took the old brackets over to his shop, cut portions off, added appropriate gussets, fabricated the new additions, welded everything together and brought the new mountings to me for paint.

After painting, I installed them, and every measurement, bolt hole and connection was a perfect fit! After tying the shaft in its most comfortable position, I then set about aligning the transmission mount with my prop shaft, which required MANY adjustments, both in height and left to right positioning of the engine, every adjustment a BEAR!. When I finally got the mating perfect (zero thousands difference anywhere along the couplings), and tightened down all of the mountings, I realized that the shift cable needed to be re-routed to position it to shift the transmission in reverse by pushing the shift lever forward, since my prop is a LH turn. Much aggravation and planning finally got that done.

The rest was cleaning up details (reinstalling my dripless shaft seal, reinstalling my golf cart battery tray that sits on the bilge cover and powers my windlass and bow thruster, starting the engine and testing the shift lever for smoothness and proper forward and back positioning, etc.

The boat is now going in the water as soon as the hauler gets a slot after the 4th. Can't wait! I'd love to take my friend out for a spin to demonstrate how all his planning and skilled fabrication skills have worked, but he has a gorgeous Grand Banks trawler in the slip next to me, so my little Albin doesn't have much allure.


My takeaways:

Boating friends are not only great people with whom to share our passions, but invaluable to DIY boaters.

I learned my friend is extremely talented with steel, aluminum, and other metals. His shop is something to behold, and metal fabrication is also a business for him. My wife is helping me plan how to show my appreciation for what he did for my project (It would have cost me 1,000's of dollars to have someone do what he did).

Think long and hard and do lots of research before deciding not to rebuild existing trans in favor of getting a more modern one. In retrospect, I should have simply had the Hurth rebuilt.

Next project I need to remember the phone in my pocket and take pictures that I failed to do on this project.

Dick

[Beta Don]

Think long and hard and do lots of research before deciding not to rebuild existing trans in favor of getting a more modern one. In retrospect, I should have simply had the Hurth rebuilt.

If you're going to keep the boat for a long time, I think you went the right way - There is a world of difference between the old Hurth cone clutch transmissions and a ZF hydraulic unit - You will not regret the time, effort and expense once you start using the boat again

When I repowered my A27, I bought a rebuilt Yanmar 100 HP turbo intercooled engine from a Yanmar distributor. He did not have the matching transmission that originally came with the engine - The engine had been pulled from a sailboat and replaced with a new one under warranty, so the original transmission was still in the sailboat. He did have a pair of brand new ZF-45A hydraulic transmissions laying around from a project that never came to fruition, so he threw one of those in with the deal. That trans is rated for up to 300 HP in a pleasure boat, so it was a bit of overkill for my little Yanmar, but I'm sure it will outlast both the engine and the boat

I had to fabricate all 4 mounts to put the engine/trans in the boat and like your project, it wasn't a simple task. It took some time - I lifted the engine in and out twice before I got everything 'right' - But because I designed and fabricated everything myself, it cost me next to nothing. I made the brackets out of stainless plate and used stainless threaded rod and stainless aircraft hardware. I tack welded everything together and had a friend who is an expert welder do the finish work. He refused to charge me anything

This was the first hydraulic trans I've ever owned or used and what a dream it is when compared to the older technology - Shifts are smooth as glass and if you go from forward to reverse quickly without getting back to idle, it doesn't hurt anything. I know I loved using it and never regretted all the extra work, and I suspect you will feel the same once you start using yours

Don