Changing Pump Rotation on a Velvet Drive
By Chris, Hale Marine · 40+ years rebuilding Velvet Drive and ZF transmissions
Step by step
- Loosen and remove the bolts around the pump.
- Tap the pump loose. There's a little appendage on the pump that's a good spot to hit. On an old transmission you might have to hit it several times.
- Rotate the pump 180 degrees, so the cast arrow on the pump points to the same direction the engine turns, the opposite side from where it started.
- Reinsert the bolts. The transmission is now set for the opposite hand rotation.
What pump rotation actually changes
This is the part that trips people up: changing pump rotation only changes which side of the pump the fluid gets pumped to, matching the direction your flywheel turns. It does not change which shift-lever position (forward or reverse) drives the boat forward, and on a standard 71C/72C it does not change the output shaft's rotation direction either. Before doing anything else on a cast-iron unit, bump the starter and watch the flywheel direction, then check the arrow on the pump. If they don't match, you'll get no line pressure and the transmission's not going to move.
One exception: on the 1.88:1 and 1.91:1 reductions, the output turns opposite the input by design. Every other 71C/72C in-line ratio, including the 2.10:1, turns the same way as the input. On a 1004/1005 V-drive it's set when the unit is built: a gear drive turns the output the same way as the engine, a chain drive the opposite way. Re-indexing the pump never flips any of that; it only sets which engine rotation the pump can pull from.
Why the pump direction matters at all
The pump has a crescent-shaped piece inside it. As it turns, fluid comes around the crescent, gets forced out of the gears, and pushes into the forward/reverse adapter and on through the passage to the selector valve and the rest of the transmission. That's why the arrow on the pump needs to go the same direction as the flywheel. It has nothing to do with which shift position the boat moves forward in.
Why getting this wrong is expensive
The shift lever has to be in the forward position to go forward. If you run it in the reverse position to make the boat go forward, you'll cook your transmission. We've torn down a 1017-004 that had been run this way: it melted and destroyed the gears in the planetary, and ate the drum. Flipping pump rotation won't change which lever position is forward, so if yours feels backwards, give us a call before you run it.
A cast-iron 71/72 isn't bi-directional. It only drives the boat forward the way the engine turns it, in the forward lever position. It only works by following the engine rotation. If the boat backs up with the lever in forward, flipping the pump won't fix it, and running it in reverse to go forward will cook it. Call us before you run it.
Paragon transmissions: different procedure
Paragon transmissions use a different plate to access rotation. Take the two recessed bolts holding the plate off, one on top and one on the bottom. Do not touch the bolts that hold the pump on. When you lift the plate off, hold the input shaft down at the same time. Pulling the plate up on its own can drag the input shaft with it and break the sealing rings. For Ford applications, Chris doesn't remember Paragon ever making one that ran opposite of automotive rotation.
ZF and 5000-series note
ZF transmissions and the 5000-series Velvet Drives work differently. They only work behind an engine that turns counterclockwise at the flywheel. Velvet Drive calls that a left-hand engine; ZF's paperwork calls the same engine right-hand turning, so read carefully if you're cross-shopping the two.
You still get either propeller rotation out of a 5000 or Liberty. There's no pump to flip. Reversing which way the boat goes is set at the shift cable, in how you rig which lever direction is forward. Asked directly whether you reverse a 5000 that way instead of at the pump like a 71/72, Chris confirmed: yes.
Questions about your setup before you start? Call (804) 333-3677, Monday through Friday 9 to 3 Eastern, or email sales@halemarine.com.
Related guides
Common questions
Does changing pump rotation change which way my propeller shaft turns?
No. It only changes which side of the pump the fluid is directed to, matching the engine's flywheel rotation. It doesn't change which shift lever position drives the boat forward or how the output turns relative to the engine. On the 1.88:1 and 1.91:1 reductions the output always turns opposite the input; that's built in, and re-indexing doesn't change it.
Can I re-index the pump on a CR-2 or a 2.10:1 in-line unit?
No. Velvet Drive's installation manual says both must stay at their factory pump setting. On the 2.10:1 the planetary parts are different for each rotation, and the factory doesn't cover failures from re-indexing one. Call us before you touch either.
How do I change rotation on a Paragon transmission?
Remove the two recessed bolts holding the rotation plate (not the pump-retaining bolts), and hold the input shaft down while lifting the plate to avoid breaking the sealing rings.
Sources
Public documents we used for this page. Links open other websites in a new tab.