OMC Cobra Stern Drive Tech Info Part 1

Written by Stuart Hastings
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Introduction and History


     When some critical Volvo patents expired, Outboard Marine Corp. redesigned their stern drive product and named it the "Cobra." This stern drive was mated to many different engines, and was routinely installed on a wide variety of boats. The first Cobra shipped in 1985.

     Everyone agreed the new Cobra drive was an improvement over the predecessor "stringer mount" drive, including many existing boat manufacturers that owned large inventories of the now-obsolete drives. Since these manufacturers didn't want to get stuck with un-salable stern drives, they pressured OMC into limiting Cobra shipments until they could clear out their existing inventories. Thus, the Cobra didn't ship in volume until the 1986 model year. Thanks to Carl G. Craver for this tidbit.

     Some early Cobras ate their gearsets. OMC initially thought the clutch dogs were disengaging due to insufficient "bite" (interference cut) on the clutch dog teeth. OMC increased the bite angle from two to five degrees, and all subsequent Cobra clutch dogs have five-degree teeth. All known Cobra owners got a letter promising warranty coverage if any gearsets failed.


                       OMC Recall


     Unfortunately, the five-degree clutch dogs did not solve the problem, and in the following year, OMC re-diagnosed the trouble as sticky shift cables. Cobra owners got another letter, inviting them to deliver their boats to an OMC dealer for a free redesigned cable. OMC would replace any cable that failed for free, and if a cable failure destroyed a gearset, OMC would replace the gearset too. The last time I checked (1997), a Cobra gearset was almost US$1000 (labor extra).

OMC finally ended this extended warranty in early 1994.


     I believe the redesigned cable has truly fixed the problem. Alas, many people in the marine business clearly remembered the gearset troubles, and forgot (or never heard of) the subsequent cable recall and resolution. Many of these folks are "still around," and they have contributed to the Cobra's (undeserved) troubled reputation today.


     The Cobra was produced until 1993, when OMC redesigned it to use a cone-clutch shifting mechanism originated by Volvo-Penta. I don't know if OMC purchased gears and etc. made by Volvo, or just copied Volvo's design. OMC was having financial difficulties at that time, and sold a 50% stake in their stern drive business to Volvo-Penta. This new stern drive is available with one prop ("SX") or dual props ("DP"). The new SX/DP drive retains many of the original Cobra castings.


     OMC has since been taken private by another company, and sold their remaining interest in the stern drive business to Volvo. OMC and Volvo have agreed to supply parts to each other, but OMC has left the stern drive business. OMC continues to purchase SX and DP drives for boats produced by OMC subsidiary companies.


     OMC went bankrupt in December 2000. Bombardier has purchased the outboard business and the Evinrude and Johnson brand names. Bombardier is supplying Cobra stern drive parts, with some price increases.

     My understanding is that OMC still exists as a legal entity, but they've closed their business, and sold off the rights to their products. I gather they still own their Waukegan headquarters, mainly because they polluted it badly and it's now a Superfund site.



Part 4 How To Adjust Your Cobra Shift Linkage

Part 3 OMC Cobra Stern Drive Tech Info

Part 2 Problems with the Cobra

Part 1 OMC Cobra Stern Drive Tech Info


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Recreated with the permission of the Author for CBOC



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