Go Back  Offshoreonly.com > Technical > Drives and Lower Units
Bravo basics in gearing >

Bravo basics in gearing

Notices

Bravo basics in gearing

Thread Tools
 
Old 04-14-2016 | 11:22 AM
  #1  
Thread Starter
Registered
10 Year Member
 
Joined: Oct 2013
Posts: 2,888
Likes: 148
From: SF Bay Area
Default 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.
Baja Rooster is offline  
Reply
Old 04-14-2016 | 12:30 PM
  #2  
Griff's Avatar
Charter Member # 55
25 Year Member
Charter Member
Super Moderators
 
Joined: Oct 2000
Posts: 20,249
Likes: 2,497
From: Omaha/LOTO
Default

The upper gears change the ratio for a regular Bravo
Griff is offline  
Reply
Old 04-14-2016 | 01:24 PM
  #3  
vintage chromoly's Avatar
Gold Member
10 Year Member
Gold Member
 
Joined: Sep 2011
Posts: 2,643
Likes: 18
From: cleveland ohio
Default

Buying a prop will be much cheaper.
vintage chromoly is offline  
Reply
Old 04-14-2016 | 08:55 PM
  #4  
Thread Starter
Registered
10 Year Member
 
Joined: Oct 2013
Posts: 2,888
Likes: 148
From: SF Bay Area
Default

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.
Baja Rooster is offline  
Reply
Old 04-15-2016 | 05:01 AM
  #5  
Registered
 
Joined: Nov 2006
Posts: 1,261
Likes: 2
From: Great Sacandaga Lake, NY
Default

How much Power did you add??
Rattlesnake Jake is offline  
Reply
Old 04-15-2016 | 03:09 PM
  #6  
Thread Starter
Registered
10 Year Member
 
Joined: Oct 2013
Posts: 2,888
Likes: 148
From: SF Bay Area
Default

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.
Baja Rooster is offline  
Reply
Old 04-16-2016 | 04:26 PM
  #7  
BUP
Banned
 
Joined: Jul 2011
Posts: 9,594
Likes: 46
From: Ft. Worth TX
Default

gear ratios go hand and hand for where the highest torque output lands in what rpm range. That range is important for marine apps
BUP is offline  
Reply
Old 04-17-2016 | 02:01 AM
  #8  
Griff's Avatar
Charter Member # 55
25 Year Member
Charter Member
Super Moderators
 
Joined: Oct 2000
Posts: 20,249
Likes: 2,497
From: Omaha/LOTO
Default

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.
Griff is offline  
Reply
Old 04-19-2016 | 09:33 AM
  #9  
Registered
10 Year Member
 
Joined: May 2012
Posts: 127
Likes: 19
From: Lexington, KY
Default

How do you determine what ratio you are running? I have #6's and would like to learn.
kilo is offline  
Reply
Old 04-19-2016 | 10:09 AM
  #10  
F-2 Speedy's Avatar
Platinum Member
Community Builder
10 Year Member
Platinum Member
 
Joined: May 2012
Posts: 11,433
Likes: 3,958
From: Midwest & T-Rock
Default

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.
F-2 Speedy is offline  
Reply


Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

Copyright © 2026 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.