No Forward but Reverse Works: Velvet Drive Causes

Velvet Drive Pressure Port Location

Check these first

• Fluid level and condition. Low fluid, the wrong-weight oil, or a blocked oil-inlet screen can all cause weak pressure in both forward and reverse rather than one alone.
• Pump rotation. On a cast-iron unit, the pump has to be indexed to match your engine's rotation. Get that wrong and you can lose line pressure entirely. See changing pump rotation.
• The shift cable. Disconnect it at the transmission and move the lever into forward by hand. See checking the shift cable.
• The damper. A completely failed damper plate can leave you with no drive in either direction while the engine still revs fine. Asked exactly this, Chris answered: "Damper is most likely the problem if you don't have Forward or Reverse." See damper plate noise in gear.

Why forward goes before reverse

In Chris's experience forward needs more pressure to hold than reverse, so it's the first thing to act up when something starts leaking internally. On a 71C or 72C there's no separate external tap for the forward clutch either: in forward, line pressure is clutch pressure, so a drop between neutral and forward points straight at a forward-clutch leak.

Pressure test

Put a gauge on the mainline tap and read neutral, forward and reverse. For actual numbers by series, see Velvet Drive pressure specs. What matters here is the pattern, not one number: pressure that's low everywhere points at the pump, the oil or the regulator; pressure that drops specifically going into forward points at the forward clutch circuit.

Common causes on the bench

• Pump indexed for the wrong rotation, low or no oil, a jammed regulator valve, or a bad pump. Any of these can show up as no drive in either direction.
• An internal leak: a hardened O-ring or a worn sealing surface. Asked what causes low pressure with no obvious external leak, Chris pointed to exactly this.
• Scratches in the selector valve bore. Hone the bore and replace the valve; if the bore won't clean up, the transmission needs to be replaced. See low transmission pressure.
• Warped or dished forward clutch plates. Asked about a rebuilt unit creeping into forward, Chris said that's usually the cause, and there's no break-in period on a rebuilt unit that would explain it away.

Velvet Drive Selector Valve white Spring

When it's not the transmission

After a repower or any relinking of the controls, check that forward at the helm actually lands in forward at the transmission's own shift lever. It's an easy thing to get backwards during a reinstall, and from the helm it looks exactly like a transmission problem.

When to call

If you've checked the cable, the pump setting and the fluid and you're still stuck, call (804) 333-3677, Monday through Friday 9 to 3 Eastern, or email sales@halemarine.com.

Related reading: lost reverse, low transmission pressure and the full troubleshooting guide.