Cobra sterndrive *800 OMC parts *Mercruiser outdrive videos

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OMC gear ratio tech support *400-800 series

GLM Aftermarket Stern Drive Tech Support for 400-800 Stringer Series

  • GLM aftermarket replacement gears for OMC sterndrives years 1969 to 1985.
  • Please Note that years 1969 to 1972 will require changing the ball gear to the newer type with nut, as older outdrive will have press on ball gears installed on them.

22510 21-16 gear set bearings

22510 21-16 gear set bearings

P/N 22510 21/16 Upper gear case $599.89
OEM 982261

21-19 gear ratio can be changed to 21-20 single engine boats with original gear set of 21/16 that are 24 feet long or with original motor should go with 21-17 gear ratio to make up for compression loss, and weight.


30 Minute free tech help service comes with any OMC upper gear case gear sets sold. Purchaser needing help with shimming or any stern drive related problems please phone 4pm to 7 pm west coast USA time.

We have Tech service illustrations with exploded drawings for the do-it-yourself mechanics new to boat repairs. See 800 / 400 Stringer series upper gearcase drawings and layouts to find parts needed for your stern drive repair.

22590 gears bearing retainer assemble

22590 gears bearing retainer assemble

The following are a list of stern drive parts that you may require to repair outdrive units. They are as follows.

Seal kit # 87650 years 1973 to 1986
Seal kit # 87651 years 1968 to 1972
Plastic shim kit # 23310
Shim kit # 23510 (stainless steel) for driven gear
Shim kit # 23320 (stainless steel) for small timken bearing located at rear of drive case
Loctite aviation gasket sealant # 30517, 680 or 609 Loctite for outside of seals and inside gear shaft to ball gear area.