How to Test Evaluate Velvet Drives ???

Natchamp · Post by **Natchamp** » Wed Jul 20, 2011 9:02 am

Gents,

I'm looking for advice on how/what to service on my velvet drives. The boat is on the hard and hasnâ€™t been run in a couple of years. Iâ€™m about ready to fire the engines up for the first time (for me). Iâ€™m trying to ascertain what, if anything, needs to be done to the drives.

From searching and reading posts it appears these drives are generally pretty strong and dependable with the disks being the main components that might need attention? Is there a simple way I can test the shape of the clutch discs? I think I read somewhere that one way is to start the motor and see if the propeller spins while the tranny is in neutral. If it does then you might need new disks, is this true?

Should I take the trannies out and replace the disks to be sure? Any other bearings or seals to look out for? I donâ€™t want to crack them open if I donâ€™t have to but the last thing I want is to rebuild this whole thing, put it in the water only to find out I have a problem with the drives!

Please advise.

BobCT · Post by **BobCT** » Wed Jul 20, 2011 9:27 am

that's a tough one w/o really being able to get them up to temp and test under load. I think I would rig up a few hoses, one for the engine (assume you've got that covered) and one for the cutless bearing.

Then, run each side in gear for a while. You can get up to around 1,500 RPM's on the hose for 5 mins at a time, you can idle all day. The rebuild kits aren't that much and extremely easy to do from what I've been told.

Some rotation in neutral is ok but it should be very low, like you could almost count the revolutions. Realize you won't have the resistance of the water on the prop. You should be able to easily stop it with your hand. Any more than that and new clutches might be in order.

Yes, these are pretty solid transmissions and are probably good as long as they weren't run low on fluid or got water in via a bad "U" cooler.

Bob

wowzer52 · Post by **wowzer52** » Wed Jul 20, 2011 11:27 am

These trannys are pretty bullet proof. It has been my experience that sitting doesn't harm them. If it did there would be thousands of them being changed every year, not counting the ones that sit on shelves. Is there a reason why you would think they could be bad? Smelling the oil will give you an idea of the condition and changing the oil is always good. Also, if you have doubts, have a marine transmission mechanic check them out. If you did put the boat in the water and had a trans problem, most transmissions can be pulled with the boat in the water. Then again, if you do run the boat out of the water you will have to cool the cutless bearing and packing while supplying water to the raw water intake. Good luck.

Natchamp · Post by **Natchamp** » Wed Jul 20, 2011 11:34 am

Thanks guys, much appreciated. I don't have any reason to think they need attention, just trying to cover all my bases. cheers.

prowlersfish · Post by **prowlersfish** » Wed Jul 20, 2011 1:13 pm

Chances are you will be ok some rotation in neutral is normal , some do it some don't .