ZF63A port side transmission spins in neutral w/engine running

[Cliffm]

Source of the post This has nothing to do with the reverse gears, but is a transmission issue. There could be a seal bad in the valving or some clutch disc issues.

I would venture to say it's a clutch disc issue, as you noted that the shaft was hard to turn during haul-out. That indicates to me that something is staying engaged, if only partly.

As Denpooch noted, this could be a $5K issue, in having the trans pulled and rebuilt, or replaced. If you can't bargain with the whole price or having it fixed before closing, I wouldn't be too discouraged. Depending on your capabilities, you could have it corrected for less, or much less. When I purchased my boat it had a bad transmission. I was able to remove it, get the parts, and rebuild it over the winter for about $200. It's been working in the boat now for 25 years.

I intend to get the "old" trans as it only has 217hrs and the control valve has no wear... and do the clutch pak rebuild myself, to keep for the future. I'm hearing the clutch paks are Ford C4 style, I've rebuilt many Ford trans, manual and auto... for now, getting it up and running, without dragging someone off the dock is the goal! Gotta practice driving this "twin screw" setup...which everyone is telling me si so much easier!

[Cliffm]

Source of the post This has nothing to do with the reverse gears, but is a transmission issue. There could be a seal bad in the valving or some clutch disc issues.

I would venture to say it's a clutch disc issue, as you noted that the shaft was hard to turn during haul-out. That indicates to me that something is staying engaged, if only partly.

As Denpooch noted, this could be a $5K issue, in having the trans pulled and rebuilt, or replaced. If you can't bargain with the whole price or having it fixed before closing, I wouldn't be too discouraged. Depending on your capabilities, you could have it corrected for less, or much less. When I purchased my boat it had a bad transmission. I was able to remove it, get the parts, and rebuild it over the winter for about $200. It's been working in the boat now for 25 years.

it is warped steel plates, got too hot according to Gunnar Hatton, which then eliminates the required clearance to "spin freely" in neutral. Needs new steel plates... I plan to keep the pulled trans and rebuild myself, since I hear its basically ford C4 auto drive pack. Done those several times, as well as manual toploaders.

[Cliffm]

Brand new trans installed and maiden voyage yesterday, all is good! But having a bow thruster for backup is even better.

Thanks to all for the insightful feedback.

[bud37]

Good stuff thanks for posting.....it would be interesting when you get the new steels in to see if the clutch pack stacks up well in the accepted tolerance or on the tight side.....I have done a few trans but all mopar 727.....good luck with your new boat.......

[km1125]

Thanks for posting the update!

Keep a careful eye on that trans initially for trans temp. Unless you know how the old one got heated up, you might still have an issue that you need to address. Perhaps it was just due to some low fluid though, or the operator not putting it all the way into gear when under a load.

On mine, the PO didn't realize that the dipstick had popped out and gushed a lot of the fluid into the bilge. He ran for a while and got it so hot that ALL the rubber seals inside (all the o-rings) had melted and ended up as a blob in the bottom of the case. Luckily it didn't do any more damage than that. The case got so hot that it baked the paint so well that it could not be burned off when I went to rebuild it. The shop said they had never seen paint so tough and they had done all kinds of gear boxes and engine blocks.