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-   -   Bravo basics in gearing (https://www.offshoreonly.com/forums/drives-lower-units/336389-bravo-basics-gearing.html)

Baja Rooster 04-14-2016 11:22 AM

Bravo basics in gearing
 
I apologize if this has been beaten to death already but I did a search with no solid answers.

My Bravo 1 originally had the 1:5 ratio but the previous owner changed it to 1.65:1. Is the gearing change in the upper, lower, or both? Can I just buy one half with the 1.5 ratio?

Also, does a billet top cap help reliability?

My Baja 272 is currently propped with the 1.65 setup but I just upped the power and figured reverting back to the original ratio would be easier than buying new props as I have a variety for different conditions.

Griff 04-14-2016 12:30 PM

The upper gears change the ratio for a regular Bravo

vintage chromoly 04-14-2016 01:24 PM

Buying a prop will be much cheaper.

Baja Rooster 04-14-2016 08:55 PM

I'll probably just grab another whole drive and keep this one as a spare. Anyone try the billet caps on the B1 with any improvement? I heard that it helps keep the cases from flexing but haven't heard any first hand experience.

Rattlesnake Jake 04-15-2016 05:01 AM

How much Power did you add??

Baja Rooster 04-15-2016 03:09 PM

Unsure yet, but it should be right about 600-650 total. I know a B1 is inadequate but have read everything from people running their 800hp with no problems to blowing them up with the stock 454 mag. I'm just hoping to get through the summer and sort that out next winter.

BUP 04-16-2016 04:26 PM

gear ratios go hand and hand for where the highest torque output lands in what rpm range. That range is important for marine apps

Griff 04-17-2016 02:01 AM

If you added more than about 100-120hp, then the gear change from 1.65 to 1.50 will probably not be enough to reuse the props you have anyway.

kilo 04-19-2016 09:33 AM

How do you determine what ratio you are running? I have #6's and would like to learn.

F-2 Speedy 04-19-2016 10:09 AM

If the drive is off, you can count revolutions of the drive input shaft, compared to the prop. If it is a 1.5 drive, the propshaft will make 1 turn, and the input shaft will make 1.5 turns, or to make it easier to see,, for every 3 turns of the input shaft, the propshaft will turn 2 times.


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