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-   -   Changing gears in Number III's (https://www.offshoreonly.com/forums/drives-lower-units/271287-changing-gears-number-iiis.html)

bigboat28 02-23-2012 12:19 PM

Changing gears in Number III's
 
Anyone have an idea what it would cost to change my gears from 1.33 to 1.50?

RMPRam 02-23-2012 01:11 PM

It depends what ratio upper gears you have combined with your lower gear set. You may have a 1.18:1 upper set combined with a 1.125:1 lower( you multiply the ratios to get the final ratio of the drive) to get a 1.33:1 drive or you could have a 1.33:1 upper with a 1:1 lower for a 1.33:1 drive.
The best combination would be the 1.18 upper because then you only have to change it to a 1.31:1 upper ( whic.h I have in a straight cut forged gear)
to make a 1.48:1 drive. The original Mercury 1.33:1 uppers are not as strong as the new forged gears that I have.
Gary
612-247-7081

FIXX 02-23-2012 06:51 PM

fixx
 
wouldn't it be cheaper to change the trans ratio?

RMPRam 02-23-2012 09:42 PM

I don't think that is advisable/possible. All the Velvet Drive transmissions that I have seen used with the SSM drives, whether they are # 3, 3A, 4 or #5 drives have all been 1:1 ratio. I don't think you want to mess with the gear ratio in the transmission.

dereknkathy 02-25-2012 01:23 PM

you CAN'T change ratio in a velvet drive. you CAN add a reduction gear to the back of it like every inboard shaft boat has. but then you have to move motors forward 4 to 5 inches and find a nonexistant coupler to the outdrives.


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