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Changing from AQ280 to DP Drive

You need an AQ series 1.95:1 Duo Prop lower unit in good working condition.
The engine determines the over-all drive ratio.... in your case, the 5.7L suggests the 1.95:1.
No other ratio will work correctly, with exception to an extremely small/light weight/fast hull, whereby the 1.78:1 may work!


You'll also need:

  • if the DP is short shaft, you'll need a long vertical shaft spline coupler.
  • a tool suitable for removing the bearing race from the Intermediate housing.
  • the original Duo Prop vertical shaft tapered roller bearing race (try not to mix/match these).
  • a good micrometer, and a good depth micrometer.
  • a hand full of small value OEM shims.
  • the OEM service manual pertaining to dimensions A and B.
  • note that this is a Negative pre-load... not Positive.
  • drive oil now changes to GL-5.
Special note:
If you've been running a LH single prop, I'd encourage you to examine the transmission vertical shaft brass split ring keeper... (aka wear washer).
If this is showing any signs of expansion, it should be changed.
See your OEM manual pertaining to this parts and related clearance spec.

Prop determination uses the same WOT RPM procedure as does a single prop determination.
The AQ series DP for gasoline engines require the "B" (aluminum) or "C" (SS) series propellers. No thru-hub exhaust!


Next.... pick up some neck braces for YOU and your passengers! :cool:

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