Velvetdrive less propulsion on one side.

[91Veteran]

Question about Velvetdrives.

I have a 1983 Carver 3207 with Velvetdrive transmissions, Model 1017-007 as shown on the plate. I believe these may be considered 71C's.

I was cruising a few days ago and seemed to lose forward propulsion on one side. After a bit of fiddling around, checking, etc., it appeared the upper control for that side was not fully engaging in forward. Reverse seems to have expected thrust similar to the other side.

The reason I am thinking the upper control was not adjusted properly is from operating the upper control and watching the transmission, going to neutral, then operating the lower control and watching the transmission. The lower control seemed to fully engage forward with proper thrust.

I adjusted the upper control and thought I had everything fixed. We went out and cruised with what appeared to be good propulsion from both sides. After some swimming, we headed back to the marina, but again it was acting up and seemed to have less thrust than the other side.

While under way back to the marina, I looked at both shafts, and both were rotating as expected, but the one with less thrust appeared to be spinning slower than the other. Of course, this was just eyeballing it.

Oil levels in both was good.

Any thoughts on this? Could the lower controls also need adjusting to allow the upper control to fully engage forward? Could there be an adjustment of the linkage at the transmission that would allow the upper control to fully engage forward? Is there some other reason why that side appears to have less propulsion in forward than the other side?

Are these drives similar to a hydraulic motor where a little oil flow allows the motor to operate, but less fast than at maximum oil flow? Or do they operate where if they are forward or reverse, they just operate?

[bud37]

Welcome.....try disconnecting the cables at the trans and than shift the trans manually each way ( F / R ) and note the deflection amount then reconnect the cables and watch to see if they are restricting the travel and adjust as needed. The trans have clutches, is the fluid still a nice pink color ?

That is what I would try first.....there should be some other suggestions from some more experienced with these trans.

[km1125]

You need to check out how the cables are run. Do the upper station controls go to the lower station controls and then a single cable down to the engines/trans, or does each station have a cable all the way down to the engine/trans. You can tell just by looking in the engine compartment at the carb and the trans linkage. Are there two cables on each or just one? (posting pictures helps folks understand your situation better!). If the controls "daisy-chain" (the upper controls go to the lower controls and then to the engine/trans), then you'll have more "slop" in the upper controls. Still manageable, but might need to spend more time on adjustments. You could also have some stretch in the control cables that will cause even more 'slop' and might need to replace them at some point.

The trans are operated by hydraulic clutches. They should be "full on" or "full off" and nowhere in between, or that means there's slipping. Slipping could be caused by low hydraulic pressure, or by worn out clutches. If it slips for too long then the fluid will be burned (and could potentially boil out of the housing). It will start turning a darker color. If the fluid has lost viscosity over time then the pump might not be able to build sufficient pressure...when was the last time the fluid was changed?

There is also a screen (filter) in the return cooling hose into the base of the transmission. That could get clogged up which could also cause a loss of pressure. Too much fluid in the case can also cause it to foam and lose pressure... is the oil the correct level?

You should be able to compare the port and starboard sides and look at the transmission shift lever. Put each station in each gear (F, N, R) and see where the transmission shift lever ends up. The engine does not have to be running to do that test.

[91Veteran]

Source of the post Welcome.....try disconnecting the cables at the trans and than shift the trans manually each way ( F / R ) and note the deflection amount then reconnect the cables and watch to see if they are restricting the travel and adjust as needed. The trans have clutches, is the fluid still a nice pink color ?

That is what I would try first.....there should be some other suggestions from some more experienced with these trans.

Thanks for the response. I plan on doing this next to see just how far forward it should go. The fluid is a little darker than the other trans.

[91Veteran]

Source of the post You need to check out how the cables are run. Do the upper station controls go to the lower station controls and then a single cable down to the engines/trans, or does each station have a cable all the way down to the engine/trans. You can tell just by looking in the engine compartment at the carb and the trans linkage. Are there two cables on each or just one? (posting pictures helps folks understand your situation better!). If the controls "daisy-chain" (the upper controls go to the lower controls and then to the engine/trans), then you'll have more "slop" in the upper controls. Still manageable, but might need to spend more time on adjustments. You could also have some stretch in the control cables that will cause even more 'slop' and might need to replace them at some point.

The trans are operated by hydraulic clutches. They should be "full on" or "full off" and nowhere in between, or that means there's slipping. Slipping could be caused by low hydraulic pressure, or by worn out clutches. If it slips for too long then the fluid will be burned (and could potentially boil out of the housing). It will start turning a darker color. If the fluid has lost viscosity over time then the pump might not be able to build sufficient pressure...when was the last time the fluid was changed?

There is also a screen (filter) in the return cooling hose into the base of the transmission. That could get clogged up which could also cause a loss of pressure. Too much fluid in the case can also cause it to foam and lose pressure... is the oil the correct level?

You should be able to compare the port and starboard sides and look at the transmission shift lever. Put each station in each gear (F, N, R) and see where the transmission shift lever ends up. The engine does not have to be running to do that test.

I believe the cables go from upper to lower with a single cable to the trans. If the upper is moved, the lower moves with it and vice versa. I did notice if I put the upper full forward, then have the lower pushed forward, it seemed the upper might move just a little more. I saw only one cable going to the trans.

I believe the fluid was last changed when it was out of the water over the winter. I just bought the boat recently.

If the screen filter was clogged, would that cause problems in both forward and reverse? The fluid did seem to be the correct level.

[bud37]

Source of the post

Source of the post Welcome.....try disconnecting the cables at the trans and than shift the trans manually each way ( F / R ) and note the deflection amount then reconnect the cables and watch to see if they are restricting the travel and adjust as needed. The trans have clutches, is the fluid still a nice pink color ?

That is what I would try first.....there should be some other suggestions from some more experienced with these trans.

Thanks for the response. I plan on doing this next to see just how far forward it should go. The fluid is a little darker than the other trans.

Dark smelly fluid can indicate clutches wearing...

[km1125]

Source of the post
I believe the fluid was last changed when it was out of the water over the winter. I just bought the boat recently.

I'd be VERY suspicious if the fluid was changed just before I bought a boat!! Normally, that's one of the FIRST things you should do when you get it, so you have known good fluid in there (applied to all fluids).

Source of the post
If the screen filter was clogged, would that cause problems in both forward and reverse? The fluid did seem to be the correct level.

It might, but also might not be as noticeable, as you usually don't develop the same torque in reverse and also the reverse clutches probably don't have the same wear as the fwd clutches have.

[91Veteran]

Source of the post

Source of the post
I believe the fluid was last changed when it was out of the water over the winter. I just bought the boat recently.

I'd be VERY suspicious if the fluid was changed just before I bought a boat!! Normally, that's one of the FIRST things you should do when you get it, so you have known good fluid in there (applied to all fluids).

Source of the post
If the screen filter was clogged, would that cause problems in both forward and reverse? The fluid did seem to be the correct level.

It might, but also might not be as noticeable, as you usually don't develop the same torque in reverse and also the reverse clutches probably don't have the same wear as the fwd clutches have.

I plan on changing the fluids this weekend. Attached is an image of something I modified that should help. Attach my little shop vac to the gray PVC and insert the tube in the fill hole for the trans and suck it into the bucket.[img]

IMG_20230606_101414.jpg

[/img]

[km1125]

Source of the post ....
I plan on changing the fluids this weekend. Attached is an image of something I modified that should help. Attach my little shop vac to the gray PVC and insert the tube in the fill hole for the trans and suck it into the bucket. ...

I made something similar to that and it works great. One BIG addition I added was a speed controller for the vacuum. When the vacuum is on full there is so much suction and "activity" inside the bucket that you end up sucking a lot of oil mist into the vacuum and making a mess. With the speed controller you can reduce it so that there's enough suction to pull the oil, but not enough to make a mess in the vacuum. You could get the same result if you put some baffles inside the bucket before the gray PVC connection.

[91Veteran]

Source of the post

Source of the post ....
I plan on changing the fluids this weekend. Attached is an image of something I modified that should help. Attach my little shop vac to the gray PVC and insert the tube in the fill hole for the trans and suck it into the bucket. ...

I made something similar to that and it works great. One BIG addition I added was a speed controller for the vacuum. When the vacuum is on full there is so much suction and "activity" inside the bucket that you end up sucking a lot of oil mist into the vacuum and making a mess. With the speed controller you can reduce it so that there's enough suction to pull the oil, but not enough to make a mess in the vacuum. You could get the same result if you put some baffles inside the bucket before the gray PVC connection.

I was thinking maybe a trash bag liner to help keep things clean. The tube in the bucket goes to the bottom, so I hope that help keeps down any mist.