Transmission issues???

R

Redhook98

Member
GOLD Sponsor
Aug 28, 2008
937
Colonial Beach, VA
Boat Info
2007 Sundancer 40
Engines
Cummins QSB 380
I have only had the new (to me) 340 out for a few small trips so far. One thing I noted is that the Port shaft will turn even in neutral. I have had this happen with other IBs that I have owned in the past, but not like this.

It has the Velvet Drive 1.52-1 trannies. When in neutral, the Port shaft will spin, and you can't stop it with your hand. The other IBs I have had you could stop it with your hand (simple viscous reaction). Not so with this one. Tried playing with the position of the shift levers, no joy.

I changed the transmission fluid when I first noticed this after coming back from a short trip. It barely registered on the dipstick and came out almost black. It slipped a few times on that run also. Yeah, not good.

Seems to be shifting great now and does not slip at all. Any ideas?
 
Yes, you have warped forward clutch-plates, due to slippage at sometime in the past, possibly a low oil situation and powering up or possibly the lathe cut rubber rings are getting hard and cannot seal. its a problem that is not going to cure itself and ADDITIVES wont help and will only aggravate the problem and cause more damage.
to explain what exactly is happening, you've lost the .018 to .035 forward clutch clearance and the clutches are touching the steels and dragging.
to give you an idea of the cost of the repair on the bench, not R and R at my shop is around 850.00, dont let anyone hit you for more than that or they will be taking your money. thats what we get for a complete overhaul with a 1 year warranty
 
now you know how i chose my screenname, no pun and sorry to hear your having problems, but with transmssions on boats its easy to get burned....i hear many, many stories
 
Thanks for the input. I have a few questions for you. First, can the tranny be pulled while the boat is still in the water? I realize you would have to be careful about he shaft sliding, but am condient I could secure it. Second, is throwing a clutch pack into one of these that difficult to do myself? I have been rebuilding engines and auto trannies all my life so I know my way around a wrench. These trannies were rebuilt a few years ago. I spoke with the PO and did NO maintnenace to them, nor did he ever check them. Doh!

I also looked around and have found good tested used units from anywhere between $400 and $800. I need the 1.52 gear ratio model and believe it is a 71C or a 72C (?)

Now for the really dumb question...... Are the clutch packs resident in the forward larger area of the tranny, or the rear, smaller area? (not talking about the nose cone.)

What would be the harm in using it as-is for awhile? It's not so bad where it is "clunking into and out of gear and does not spin any faster when revved up in neutral. Not making any wierd noises either.

Thanks! And I figured your name was for that reason when I saw it. Lol!
 
yes, the trans can easily be pulled in the water, and the forward clutch pack is in the front section of the trans, my first 2 tranny's this year were from customers that had them rebuilt or tried rebuilding themselves...my high for one year, because i mark them on my board as re-runs was 14, not mine but the same as above...some guys can breeze thru them without a hitch. it all depends on your mechanical skill level and understanding of hydraulic transmission theory. btw, while its out you should also thorw a new damper plate in
 
and a real good time to do some alignments with the boat in the water, eliminate one major cause for transmission failure. in your case i would microscope the pump also, it sounds as if the trans has been running low on oil for quite some time.
 
I cant condone you using the boat for a while because of safety issues, i can only speak for myself, yes i would until you can get a window to repair. the plates lost thier ability to hold and they may get to a point where they will weld together and then when you put into reverse it will stall the engine...then its over
 
Yes, I believe it was running low for awhile. It was black when it came out. !!! Yikes !!!
So I am staright in the head here, I would have to remove everything from the back of the engine block back, right? Will the engine balance on the mid mounts by itself alright (with the xhaust balancing it)? What all should I order? I am thinking a new damper, the clutch pack kit (which appears to have all needed gaskets). How would I micro the pump? Lol! Am I getting ino ver my head? I have always had that mechanics talent that allows me to figure things out successfully like this and have never really had issues, but I am a little unfamiliar with the way boat trannies are made up.

Better off buying a good used unit at this point?
 
stuckinforward said:
I cant condone you using the boat for a while because of safety issues, i can only speak for myself, yes i would until you can get a window to repair. the plates lost thier ability to hold and they may get to a point where they will weld together and then when you put into reverse it will stall the engine...then its over
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Yikes! Is there any warning before that happens? And is the tranny still able to be rebuilt after that? It is still very very smooth when switching from farward to reverse and vice-versa...... Just not sure when I will be able to do this....
 
One more question for you. How do I know if the damper is bad, and can I replace it with the engine still installed? By looking att he various websites, they say I can only replace iwht the engine out of the boat.. ??

I have a mechanic buddy who has done rebuilds before. He is going to do the rebuild for me. Thanks for all the info and advice!!!
 
simply remove the bellhousing and starter and one trade secret no one will tell you is leave the damper loose and pilot the transmission then reach in thru the starter hole and tighten the bolts, this will automatically center the damper for you eliminating any side loading the input bearing....dont fall for the 400.00 damper plate from Merc, call me if you like and i will get you one for 96.00, 330-273-8291
dont even second guess the damper! replace it, if its not bad now usually they will go bad in 5 more hours. lol....cheap insurance
 
Thanks again. Just ordered the kit from EBasicPower. I will us eth eboat for the weekend and probably pull the tranny on Sunday. Just looked at the trannies and they are the 72C/10-18 units. Still not sure on replacing the damper. It goes in and out of gear silently and the transissue I am experiencing now is recent. I don't think I was using/abusing the trans long enough to affect the damper. I will check it for loose springs, ect though.

The one question remaining is this: Does the engine just balance on the two motor mounts left after the tranny is removed? Or does it need to be blocked?
 
it needs to be blocked, or supported, you can put a bottle jack between the stringers and exhaust manifolds,
look for cracks on the damper plate, you'll regret someday not changing it.... your gonna say, "i shoulda changed it when the trans was out...there only 100 bucks
 
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