How to Read a Velvet Drive ID Tag

1017-001 Bushing Style Case

Where the tag is

On a cast iron 71C or 72C, the tag is on top of the transmission, on the left-hand mount. On a Liberty or 5000, it's on the mounting boss instead. "Velvet Drive" sits at the top of the tag, the model number is below that, the ratio is off to the left, and the serial number is off to the right. Cast iron tags also carry a few patent numbers.

What each field means

The model number tells you the family. Anything starting 10-17 (we write it 1017) is a 71C in-line. 10-18 (1018) is a 72C in-line. 10-04 is a 71C V-drive, 10-05 is a 72C V-drive, and 10-06 is a 73C. 10-13 and 10-14 are CR-2 units built on 71 and 72 internals.

One catch on older units: the Warner Gear identification chart lists 10-04-000-022 through -035 as 70C in-line transmissions, not V-drives. If you're looking at an old tag that starts 10-04, get the full number before you call it a V-drive.

Even and odd numbers

The last part of the assembly number tells you which way the pump was set at the factory. Odd-numbered "C" units are built for a clockwise-turning input; even-numbered "CR" units are built for counterclockwise, viewed from behind the transmission looking forward. That's only the factory setting, though. If someone re-indexed the pump later, the tag won't match what's actually in the case.

AS numbers and suffixes

Older tags carry an AS number instead of, or alongside, the 10-17/10-18 number. The 1988 service manual's front table cross-references them: AS1-71C is 10-17-000-001, on up to AS20-72CR at 10-18-000-014. The 1.88:1 reductions don't get an AS number at all, they're just 10-17-000-108 and 10-18-000-106.

Suffixes carry their own meaning. CR marks the opposite-rotation version of the same unit. AS7 and AS17 mark counter-rotating reduction units, which cover the 1.88:1 and 1.91:1. CB and CBR mean a heavier reverse-duty build, usually behind a diesel.

A quick 72C tell

Every 72C runs its reverse ratio about 10% deeper than forward: 1:1 forward pairs with 1.10 in reverse, 1.88 pairs with 2.07, 1.91 with 2.10, 2.10 with 2.31, and so on up the line. On a 71C, forward and reverse are the same number. So if a parts listing or an old invoice shows a reverse ratio about 10% deeper than forward, you're looking at a 72C.

The 1.88:1 and 1.91:1 reductions also turn the output opposite to the input. Every other in-line 71C/72C ratio, direct drive included, turns the output the same way the input turns.

5000 and Liberty ratios

The nominal ratio printed on a 5000 or Liberty tag isn't always the actual ratio cut into the gears. -001 is nominal 1.00, actual 1.054. -002 is 1.25 nominal, 1.303 actual. -003 is 1.50 nominal, 1.586 actual. -004 is 2.00 nominal, 2.040 actual. -005 is 2.50 nominal, 2.454 actual (the Liberty owner's manual prints "2.45" for this one). -006 is 2.80 nominal, 2.800 actual. So if you've seen "2.00," "2.04" and "2.45" all used for what looks like the same transmission, they can all be right, depending on whether the source is quoting the nominal number or the actual gear ratio.

No tag? Measure it, count it

Casting numbers won't help. As Chris puts it, "the number you giving us is the casting number not the model number." Casting numbers are stamped all over these cases and don't identify anything on their own.

What does help is a tape measure. A 71C runs about an inch shorter than a 72C at every configuration: 10.50 in versus 11.44 in on a direct drive, 16.89 in versus 17.79 in on a reduction, bellhousing face to output flange.

You also can't turn what you find into something it isn't. Chris has answered this one more than once: bolting a reduction unit onto a 1:1 71C doesn't make it a 1.88, because "input shaft and clutch packs are the same but not the reverse planetary assemblies. Cases are different also."

One more myth to drop

The 71/72 line isn't bi-directional. Chris: it "only works by following the engine rotation," so forward only comes out of the F position. On the 1.88:1 and 1.91:1 reductions specifically, a left-hand engine (Velvet Drive's term for an engine that turns counterclockwise at the flywheel; ZF's paperwork calls the same engine right-hand turning) pairs with a right-hand propeller. Don't carry that rule over to the rest of the line.

Still not sure?

Call us at (804) 333-3677, Monday through Friday 9 to 3 Eastern, or email sales@halemarine.com. Tell us what's on the tag, or send photos, and we can usually get you the rest of the way.

Related reading: identifying your transmission and ratio, the Borg-Warner cross-reference, and the Velvet Drive glossary.