ZF Transmissions 63IV vs 68IV

Gary Hill

Member
Mar 30, 2009
375
Holland, MI
Boat Info
2008 40DA
Engines
8.1 SHO
Hello All,
First I wish all in the hurricane area the best of luck. Looks ugly. I have not posted for a while due to another love in my life known as a 1969 Mercury Cougar which takes up all my time.

Anyway, for the second time my 2008 40 DA lost the port transmission. The first time it was under warranty and ZF replaced it with a rebuilt unit, OK fair enough. Last Saturday the rebuilt unit blew up. So now I was out of warranty and being in the spline and gear business and understanding these transmissions I decided to pull it my self and rebuilt it myself but parts cost more than a new one.

It is somewhat known about ZF 63IV's when installed on the port side having issues. From my investigation it is more prevalent then they admit. I did not want to install another problem waiting to happen.

So in my investigation I found out that ZF came out with a beefed up version called the 68IV which is basically the same as the 63IV but with a stronger case. I purchased the 68IV and it arrived yesterday and will be installing tonight. However, the bigger picture is that this new case is considerably beefed up. Especially where the counter shaft bearing pockets are. The ribs on the outside are about twice as big and they cover the counter shaft bearing pocket.

I did a search here for ZF 68IV and got no hits so I thought I would post up this experience for my fellow SeaRay owners. The take away here is that you have better options if you loose a 63IV especially on the port side.

Regards, Gary
 
Any idea if your alignment was good on the port prior?

Why is the port more susceptible to failure? Rotational direction?
 
Alignment checked at .002". I check both sides every spring after launch.

My understanding is rotational stresses in the opposite direction to starboard. 68IV is in and running fine. Install went well.
 
Gary if you still are around....I'm just curious .....what broke in the 63 transmission? Was it the shaft/gear or plate failure? Did the first 63 fail for the same reason?
 
I too have noticed a bunch of boats with the port trans replaced.
My port always had a whine since the day I got it 4 years ago. Never got better, never got worse. I wish It could be quiet like the starboard.
 
Gary if you still are around....I'm just curious .....what broke in the 63 transmission? Was it the shaft/gear or plate failure? Did the first 63 fail for the same reason?

Hello I decided to lurk and found your query. Sorry for my delay. FWIW now, the short answer is gear failure that lead to the input shaft shearing into two pieces. I'm sure the gear was first then the shaft sheared. On my first warranty covered trans, I found a chunk of gear tooth in the oil filter and am sure it was the same thing (due to warranty I didn't get to open the case and look). The gear teeth go bad due to the bearing pockets of the shaft deflecting and allowing the centerline of the shaft to move. This in turn changes the centerline distance between the gears, no good.

Douglee25, Its still working fine.

Regards,
Gary
 

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