Velvet Drive 71C/72C torque specs (1017/1018)

1017, 1018 bolt torque specification

Table 4: 71C/72C bolt and nut torques (dry)

These values are dry, non-lubricated, and cover the cast-iron 10-17 (71C) and 10-18 (72C) in-line transmissions only. The 1004/1005 V-drive and the 5000/Liberty have their own tables further down.

Output and coupling nuts by unit

The two nuts near the top of that table cover different transmissions, and the manual doesn't spell it out in one place, so here it is:

• Output shaft nut 4775L: 1:1 direct-drive 71C/72C, and early-production 1.523:1, 1.91:1 and 2.10:1 reduction units. 160-260 ft-lb.
• Coupling nut 10-00-149-034 (Hale sells it as 1000-149-034 ($47.46)): current-production 1.523, 1.88/1.91, 2.10 and 2.57/2.91 reduction units, plus the 1004/1005 V-drive box. 220-260 ft-lb. This one is not for a 1:1 direct drive; the factory uses 4775L there.

Hale sells the direct-drive nut as 4775L ($42.50); nothing in the manual calls it obsolete. A 5000 or Liberty uses the same 10-00-149-034 nut on its output flange, but torqued to a different number: 225-275 ft-lb, with a nylon insert. Don't merge the three ranges into one "coupling nut torque" figure; the unit determines the range.

Reduction preload and spacers

Current-production reduction units use a solid spacer to set bearing preload. Before bolting the reduction unit to the transmission, check rolling torque: 5 to 30 in-lb. Over 30, go to a longer spacer; under 5, go shorter. That gives 0 to 0.005 in of end play. Solid spacers come in 11 lengths, .820 to .857 in, and the bearing cup and cone are a matched pair, so don't mix an old cup with a new cone or the other way around.

Some late-1970s and early-1980s units used a collapsible spacer instead of the solid one. Don't reuse that one; running an impact gun on it a second time crushes it further and leaves a sloppy back end. See collapsible vs. solid spacers for the older preload numbers.

V-drive and 5000/Liberty differences

The 1004/1005 V-drive shares most of Table 4 above, plus a few of its own: the studs use 7/16-20 lock nuts at 50-55 ft-lb, the bearing cap goes to 125 in-lb, and its 3/4-14 pipe plug is 10-20 ft-lb (lighter than the cast-iron unit's 25-35).

A Liberty's coupling flange bolts torque to 25-43 ft-lb and its drain plug to 20-25. On a 5000, the coupling bolts go to the engine or boat builder's own spec rather than a Velvet Drive number, the drain plug is also 20-25, and the clutch-pack bolts take 16-18 lb-ft with Loctite pre-applied at the factory.

What's not in the table

Transmission-to-engine mounting bolts aren't in Table 4 at all. The manual sends you to the boat or engine builder's own torque spec and warns not to overtighten. The cooler-return line fitting is 25-35 ft-lb, but that number lives in a different table, not Table 4.

One more thing worth knowing before you go shopping for a torque wrench: identify these fasteners by part number and location, not by the thread size printed next to them. The manual contradicts itself on one bolt's length (10-00-183-021 is listed as both 5/16-18 x 1 and 5/16-18 x 1-3/8 in different spots), and it prints "3/8-18 x 1-1/8" for another, which isn't even a standard thread. Part number and where it sits on the case are the reliable way to match a bolt.

Related guides

• Output nut backing off
• Collapsible vs. solid spacers
• Don't paint the coupling face
• How we rebuild a marine transmission

Questions about a bolt or nut we didn't cover here? Call (804) 333-3677, Monday through Friday 9 to 3 Eastern, or email sales@halemarine.com.