Petra20
New member
Hello, I am rebuilding what I believe is an OMC Cobra Lower Unit.
The image is of the ID plate that is attached to the Upper Unit.
The parts in the lower unit included:
Pinion Gear: 337524 14T
Forward Gear: 987820 26T 1979 possibly
Reverse Gear: 910994 1982 - 1989 V6 V8
Clutch Dog: 914716 Sierra 18-2383 Sliding Clutch 1990 - 1993
Prop Shaft: 395209 1-3/16" Propeller Shaft Found on OMC Cobra & Johnson Evinrude 1984-1990
The unit would not stay in reverse and on inspection it was found that the dogs of the reverse gear and clutch were badly rounded.
Looking at the part numbers it appears that both the clutch dog and reverse gear had been replaced previously.
However the Shift Cradle and Lever had significant ware, which I suspect caused the damage to the dogs due to the amount of slop in the system.
I have acquired a new set of gears as listed below and a new Shift Lever and Cradle.
986656 — GEAR SET (INCLUDES FORWARD & PINION) 0987670 - Gear Set, Forward & Pinion
914726 — GEAR, REVERSE 1990 - 1993
914716 Clutch Dog: Sierra 18-2383 Sliding Clutch 1990 - 1993
Also the retainer plate was seriously distorted, but I have sourced a good used item plus circlips.
Re-assembly has been going OK until I came to torque up the propshaft bearing carrier.
At about 4Nm the propshaft becomes resistant to turn and I suspect the forward and reverse gears are pinching the thrust faces of the propshaft.
My question is, am I on a hiding to nothing trying to fit these gears to this Lower Unit or do I need a thinner thrust washer under the reverse gear?
I am considering trying some Plastigauge between the bearing carrier and the circlip to gauge the point at which the propshaft begins to bind and calculate the correct thrust washer thickness and allow for a little end play.
The forward gear and pinion appear to be OK judging by the contact pattern.
Any help gratefully received.
The image is of the ID plate that is attached to the Upper Unit.
The parts in the lower unit included:
Pinion Gear: 337524 14T
Forward Gear: 987820 26T 1979 possibly
Reverse Gear: 910994 1982 - 1989 V6 V8
Clutch Dog: 914716 Sierra 18-2383 Sliding Clutch 1990 - 1993
Prop Shaft: 395209 1-3/16" Propeller Shaft Found on OMC Cobra & Johnson Evinrude 1984-1990
The unit would not stay in reverse and on inspection it was found that the dogs of the reverse gear and clutch were badly rounded.
Looking at the part numbers it appears that both the clutch dog and reverse gear had been replaced previously.
However the Shift Cradle and Lever had significant ware, which I suspect caused the damage to the dogs due to the amount of slop in the system.
I have acquired a new set of gears as listed below and a new Shift Lever and Cradle.
986656 — GEAR SET (INCLUDES FORWARD & PINION) 0987670 - Gear Set, Forward & Pinion
914726 — GEAR, REVERSE 1990 - 1993
914716 Clutch Dog: Sierra 18-2383 Sliding Clutch 1990 - 1993
Also the retainer plate was seriously distorted, but I have sourced a good used item plus circlips.
Re-assembly has been going OK until I came to torque up the propshaft bearing carrier.
At about 4Nm the propshaft becomes resistant to turn and I suspect the forward and reverse gears are pinching the thrust faces of the propshaft.
My question is, am I on a hiding to nothing trying to fit these gears to this Lower Unit or do I need a thinner thrust washer under the reverse gear?
I am considering trying some Plastigauge between the bearing carrier and the circlip to gauge the point at which the propshaft begins to bind and calculate the correct thrust washer thickness and allow for a little end play.
The forward gear and pinion appear to be OK judging by the contact pattern.
Any help gratefully received.