Velvet Drive Control Valve

[SoWhat]

In the process of rebuilding my velvet drives. I took some photos and ginned up some power point slides. If anybody has any experience rebuilding the control valve I would like to receive feedback before releasing them to the world.

Thanks

-Gary

(Note: hyperlinks won't work until I figure out how to change default hyperlink text color in Adobe 9)

 

[Larry M]

No experience here, but a nice job. Once you release it, it would be a nice addition to the Trawler Forum Library.

 

[diver dave]

Looks very nice. I've rebuilt a couple, they didn't have the water damage. Be nice to see the O ring size??

 

[kchace]

Looks very nice. I've rebuilt a couple, they didn't have the water damage. Be nice to see the O ring size??

The correct size for a 71 or 72 is 210.

Ken

 

[sdowney717]

When I rebuilt my Velvet drive, I used garden hose water pressure applied to the port to get the clutch piston out. Popped right out of the bore.
I had no air compressor then.
I have rebuilt 4 auto trans and these velvet drives are real simple. It helps to buy the book.
White vinegar removes rust. The PDF shows a lot of internal rust, did not see that on mine. The heat exchanger leaking?

Reason I rebuilt mine, I had a leak, leak was on the forward gear housing seal to the case, something about rust on the cast iron surface had forced the seal, it was a slow leak. Clutches were perfect condition, actually I could have just cleaned it all and reassembled, but I replaced all seals and clutches. I kept them for another rebuild of the other side in case. And now I think other one has a slow leak where the gear reduction bolts to the main case.


the hardest thing was getting the drive up out of the bilge.

 

[diver dave]

A bit beyond the original question about the spool valve, but I find dissasembly of the drive gear/ring gear was not obvious in the book. It took some solid drops of the assembly onto the end of the shaft to break apart. My wooden work bench has some sizeable dents due to this, and that didn't work. Had to bang the shaft end against some "soft" aluminum plate, sitting on concrete. The end of the shaft was ok, and the thing does come apart.
It is very typical after running with low fluid (due to HE leak) for the clutches to overheat and warp. Warp is evidenced by a slow spinning prop in neutral, for those that don't know.

 

[sdowney717]

A bit beyond the original question about the spool valve, but I find dissasembly of the drive gear/ring gear was not obvious in the book. It took some solid drops of the assembly onto the end of the shaft to break apart. My wooden work bench has some sizeable dents due to this, and that didn't work. Had to bang the shaft end against some "soft" aluminum plate, sitting on concrete. The end of the shaft was ok, and the thing does come apart.
It is very typical after running with low fluid (due to HE leak) for the clutches to overheat and warp. Warp is evidenced by a slow spinning prop in neutral, for those that don't know.

That sounds like a pain.
Mine is the old style gear reduction with the bolt on rear plate.
I don't recall anything being difficult to separate.

When you examined the parts, did they all fit smoothly together?

I suppose warped clutch plates and discs would grab and cause some friction. If it is cold and the fluid is thick, your going to get some small movement of the prop shaft in neutral.

 

[diver dave]

The older units had a bolted on output flange assy. I have the complete service manual in .pdf for those that need it.