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1992 40hp Johnson Powerhead transplant to 1987 bottom sections

M

Mr. T

New member
I fell into the trap of thinking powerheads were portable to lower units on smaller Johnson outboards. I'm trying to marry a 1992(?) 48hp powerhead to a 1987 midsection and lower unit, and I'm having fits. I had to customize the shift crank and shift shaft to get the gears to shift. Then I realized the drive shaft wasn't turning. It just makes a clicking sound as you turn the flywheel. The lower unit bolts up firmly, so I know the drive shaft is in as far as it will go, but it still isn't engaging the crank. I know Johnson changed to a 17 spindle crank in 1993, but I can't find out if they changed the length of the shaft in 1989-1992 before they changed the spindle in 1993. I have a 1987 shaft, and I suspect it has the right spindle arrangement for the 1992 powerhead, but it is simply too short. I need to prove this theory before I have my shaft lengthened and ruin it if I'm wrong.

Also, I'm guessing the year of the powerhead because powerheads have no model number or year stamped on them. They just have a serial number, and Crowley Marine says it indicates I have a 1992 48hp J28ESLENB model based on that number. The number is G3193145.

Help with crankshaft lengths and spindles, please!!

Mike T in Arlington, TX
 
The spline in the 92 crankshaft is a bigger diameter.----The 87 small spline driveshaft will NOT work ! ----And did you correct the shift rod travel ?-----I believe the 92 shifts to forward with a DOWN motion of the shift rod.
 
Last edited:
racerone said:
The spline in the 92 crankshaft is a bigger diameter.----The 87 small spline driveshaft will NOT work ! ----And did you correct the shift rod travel ?-----I believe the 92 shifts to forward with a DOWN motion of the shift rod.
Click to expand...
Thanks very much for the info. Yes, I corrected the shift shaft by modifying the linkage a little and lengthening the shift rod by 5/8". I just realized today that there is no realistic crankshaft option and the botton cowling won't fit with the configuration of the 1987 transom mount.
I'm going to sell the 92 powerhead and try to find a 87 or 88 powerhead in good condition. This is a backyard project for me and not just a way of avoiding buying an intact motor.
Thanks,
Mike in Arlington TX
 
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