Way back when I was a lot younger, ZF used to make the best transmissions and transaxles for sports car racing. There were none finer. I always thought ZF made a high quality product. Even now they are on the cutting edge of transmission technology, having recently come out with 8 and 9 speed automatics for the car business.

Personally, I think the problem is not with ZF, it's inherent in the original design of the transmission which was Hurth's. Compared to the cost of the engine though, these transmissions are mighty cheap.

From what I read heat is the major problem that you can do something about though not much. Foley offers a cooler for them, small water cooled box that mounts on the side of the trans. They also recommend using synthetic lube, which I do, currently using Amsoil. It can stand far more heat than conventional lubes will and has much better lubricity. In both our boats changing to synthetic oil cut the "rattle" noise down (did not eliminate it though) as well so I view that as a good thing.

I follow the original manufacturer's recommendations for storage (fill the case full) and change duration which in our case is yearly or about 50-75 hours running since we don't motor anymore than we have to. I also am quick to get the revs up over 1100 when in gear whenever possible.

Our engine/trans are just below 1100 hours, so maybe we are getting near the magic "buck an hour" mark?

Was curious after reading these posts so checked yesterday; my transmission is the ZF Hurth, must have been replaced with the original engine by the PO. I assume atf levels would be really important, but since the fluid is clear, it is almost impossible for me to judge the level, other than atf shows on the dipstick. Any danger in overfilling? Any atf I've used in a car usually has a red tint making it easier to see on the dipstick.. Can't wait until I try to change the fluid.

Paul, it is red, you just can't see it on the dipstick: [url]http://c34.org/bbs/index.php/topic,5139.msg31528.html#msg31528[/url]

I've learned to read the level by rolling it on a paper towel.

Not a good idea to overfill, so just be careful when refilling.

Here's more transmission info: [url]http://c34.org/bbs/index.php/topic,6417.0.html[/url]

Thanks Stu,
Great information! Answers to questions that I didn't know I needed to ask.
My fluid is definitely clear which concerns me a little. Guess the next project is to change it so I know for sure what is in the transmission.

Though I haven't personally seen it for awhile, there was a very light green automatic transmission fluid on the market, no idea of the brand. would be about the color of automotive antifreeze when wiped on a paper towel, but looks clear on a dip stick. I was in the automotive transmission business many moons ago and was surprised by the green fluid when the mechanic drained the tranny of a customer's car.

One thing to note when checking the fluid is to smell it. Burning clutches have a horrid smell, one that I don't miss at all from my days in that business.