Outdrive lower unit changes years 1967 to 1993 1967 to 1977 Electric shift with oil pump 8 bolt swivel 1970 to 1977 Electric shift 10 bolt swivel 1978 and 1981 Uses hydraulic oil pump 400/800 models (recall unit) 1982 to 1985 straight mechanical shift 400/800 models 1986 to 1993 OMC Cobra and in 1988 the King Cobra (clutch dog unit) By authors Trish Dougherty / Wayne Coll

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1967 to 1970 Electric shift model with 8 bolt in swivel housing the electric shift required 12 volts to stay engaged. In 1970 to 1977 the swivel housing was changed to 10 bolt pattern.



In 1978 completely redesigned the lower unit, this new design called for a sliding clutch dog in the gearcase that would engage the forward and reverse gear with the aid of a hydraulic pump.

This clutch was manually engaged by the use of a shift cable which contained 2 inner cores (one or reverse, one for forward). The new models were called the 400 series for 4 cylinder engines and the



The early models between 1978 and 1981 unit used a hydraulic pump to assist the hydraulic shift cable to engage the clutch dog into gear.

In 1982, engineers redesigned the lower unit once again and the 1978 to 1981 was recalled and designed the sterndrive to shift with a mechanical shift cable. They removed the hydraulic shift assist pump as they found this wasn’t working properly rounding off the forward gear and clutch dog lug.



With some of the new shifting parts the new design called for the outdrive were still called the 400 / 800 series models – but were widely referred to as the mechanical shift models. This version of the 400 and 800 series were produced in Canada and the USA up to the year 1985. In 1977, they discontinued the production and manufacturing of the Stringer electric shift unit. They opted to keep the upper gear housing design the same as with the Stringer model.In 1978 completely redesigned the lower unit, this new design called for a sliding clutch dog in the gearcase that would engage the forward and reverse gear with the aid of a hydraulic pump.This clutch was manually engaged by the use of a shift cable which contained 2 inner cores (one or reverse, one for forward). The new models were called the 400 series for 4 cylinder engines and the OMC 800 series for the straight 6 cylinder, V6 and V8 engine.The early models between 1978 and 1981 unit used a hydraulic pump to assist the hydraulic shift cable to engage the clutch dog into gear.In 1982, engineers redesigned the lower unit once again and the 1978 to 1981 was recalled and designed the sterndrive to shift with a mechanical shift cable. They removed the hydraulic shift assist pump as they found this wasn’t working properly rounding off the forward gear and clutch dog lug.With some of the new shifting parts the new design called for the outdrive were still called the 400 / 800 series models – but were widely referred to as the mechanical shift models. This version of the 400 and 800 series were produced in Canada and the USA up to the year 1985.

will show unit no longer used the poorly designed ball gear system and used the modern u-joint style drive system.



Outboard Marine Company re-engineered their OMC boat sterndrive in 1986 and introduced the Cobra gearcase. Their new modern boat parts manufacturing facility was located in Lexington, Tennessee. These new models were available in a variety of OMC boat motor options; including a 2.3 liter Ford 4 cylinder years 1986 to 1987, 3.0 liter Chevy, 5.0 liter – 5.7 liter – 5.8 liter Ford and Chevy small block V8 engine ’s and the monster 7.5 liter 460 Ford big block V8 years 1987 to 1988 King Cobra. The new OMC King Cobra parts drawing will show unit no longer used the poorly designed ball gear system and used the modern u-joint style drive system. The early Cobra models did have some technical design flaws which caused some problems when shifting. The original clutch dog had a 3 degree undercut on the top of the tooth; this angle wasn’t sufficient enough to keep the clutch engaged into the gear in certain instances. The clutch was updated to a 5 degree undercut; and a shift interrupter switch was added.



Along with an updated design in 1992 for the shift detent parts these changed did help with some of the shifting issues the drive may experience. One major difference with the Cobra models compared to the Mercruiser was that when the upper housing and lower gear case were mated together – the oil cavities were connected and an oil reservoir was not needed. The outdrive needed to be filled from the bottom fill plug until the oil reached the dipstick in the top cover of the upper housing.



Another difference was that the water pump assembly and impeller were installed in the upper gear case instead of lower unit. In 1993, Outboard Marine Corporation along with Volvo entered into a joint venture and produced a hybrid model knows as the Cobra SX. This new design was all Volvo engineering with the transom being the original design. This hybrid model is also referred to as the ‘cone clutch’ model; the shifting components are heavier duty and no longer used the clutch dog system.



Outboard Marine Corporation including the Johnson/Evinrude outboard line officially went out of business in 1998 when Volvo purchased their rights and their manufacturing facility in Lexington. OEM parts are still being manufactured through BRP (Bombardier Recreational Products). Many OEM parts are still interchangeable with Johnson/Evinrude outboards; and some outboards still use the identical lower housing as the Cobra sterndrive model. Rumors have it that the 2 stroke 150 hp Johnson/Evinrude outboards had high repairs cost do to engine carbon build up at low speeds was all-so a factor.