Different gear ratios?

76Red18 · #1 10-30-2007, 05:55 PM

Motor- 99 Johnson 150
I had to replace my lower unit last summer due to the repeated

unsuccessful attempts at removing my froze in propshaft bearing carrier to replace bad bearings & seals. I tried to run a 19 pitch prop with that lower unit, but it made the motor run to tight so I put the 17 pitch prop back on and stowed the 19 for a spare. The only noticeable difference in the replacement unit was a 50-75 rpm increase(chalked up the rpm increase to the new bearings) and the white paint. I have the charcoal color scheme. I spun the hub on my 17 yesturday, so I put the 19 on till I re-hub the 17. The motor seems to handle the prop with no problems now. Are all OMC lower unit the same ratio or did I get a lower geared unit? I don't see any specs on ratios in my Seloc manual. Anyone out there knows the answer to this, feel free to respond. thanks, Richard

Fr. Frank · #2 10-31-2007, 10:32 AM

Quote:

I tried to run a 19 pitch prop with that lower unit, but it made the motor run to tight

What does "too tight" mean?

76Red18 · #3 10-31-2007, 02:53 PM

Slow to plane, slow to reach wot under load, slow throttle responce.

Fr. Frank · #4 10-31-2007, 03:50 PM

So, with no other changes, the motor with a new lower unit went from not being able to turn a 19, to now being able to turn if just fine? Or was the old lower unit not able to turn the 19, and the new one does it just fine?

76Red18 · #5 10-31-2007, 04:55 PM

The 19 seemed like too much prop with the old unit. The new unit turns it alright. 3-4 seconds to plane(15 to 18mph), probably 8-10 seconds to full speed (42mph @5500)

eggsuckindog · #6 10-31-2007, 06:49 PM

I'm pretty sure all were the same