Propeller impact damage resulting in broken gears and bent propeller
Old cracked seal that are 15 plus years old.
Shifter updates so shifter will moves with 2-5
1988 to 1993 V6, V8 counter rotating large hub 4-1/4 inch lower unit.
Common replacement components are:
First off this drive is not common and can be damage buy using a Cobra bearing carrier puller when changing the seals.
Propeller shaft is only 12 inches long and part of the bearing carrier unit.
This outdrive should only
be service by a marina that stock the parts to repair it.
OMC King Cobra
King Cobra 1987 to 1989 V8 for 7.4 and 7.5 liter engines with hub size of 5 - 3/4 inch.
Please note: the true
King Cobra lower unit should only be used for the 7.4L (454) and 7.5L (460) motors.
For the 5.7L (350) and 5.8L
(351) motors, use the standard OMC Cobra lower unit gear-case parts.
Used parts that may not be listed here are the lower gear case, gears, clutch dog and propeller shafts.
Please contact order desk for used parts availability.
Cobra outdrive transom parts drawing
Cobra transom mount diagram
Common replacement components are: Shift cable need replacement every 4-5
year unless shifter update has been installed in lower unit, if so then about every 15 years.
Broken or cracked u-joint
bellows and exhaust bellows that are 10 plus years old.
Gimbal bearings that have not been grease every 50 hr. or
1 a year.
Cobra-SX Volvo Penta upper gear case layout with both new and used parts
Yoke and drive shaft
Seal kit upper
Manifolds and elbow illustration Ford-Chevy
400 / 800 Series and OMC Cobra manifolds for use with Ford or Chevy engines
Engine exhaust failures with
over heating problems can sometimes be traced to the exhaust systems.
However before manifold unit or engine is replaced
check the water pump flow to the engine.
Test is done by testing the time to fill a 2 gallon container at idle speed
of 550 rpm to 650 rpm.
Most common boat repair is a crack or gasket leak inside the manifold that allows engine exhaust
pressure as high as 100 lbs to enter the water jackets of the manifold. This reduces or stops the 20 to 30 lbs water pump
Volvo Penta SX
Cobra SX Volvo Penta parts layout lower unit gear-case
Common replacement OMC outdrive parts are:
propeller shafts form impact damage
Cracked seals that are 15 plus years old.
Cobra SX and Volvo Penta transom parts
Common replacement parts are:
Shift cable need replacement
every 7 to 10 years.
Broken or cracked u-joint bellows and exhaust bellows that are 10 plus years old.
Gimbal bearings that have not been grease every 50 hr. or once a year.
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 all rights reserved
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 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
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.
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
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.
T.C. Electronics/Marine (416) 751-7326 Copyright 2002 to 2021 all rights reserved