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I just purchased a boat with a Bravo One XR Drive,..I am new to the inboard outboard powered boats. The drive says 1:50 ratio on the side. Could the gears be another ratio than the sticker indicates? The motor is a 572 with a blower and I would have thought that a 1:50 ratio would be to small a of a ratio and would need to be at least a 1:36. Its in a 26Mach so its not a huge boat. Also it has an SC lower on it but I cannot find any numbers on it. Does the lower play a part in the ratio or just the upper. Is there anyway to verify the ratio?:D

Any info would be helpful.
 

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DRIVE SHAFT HOUSING
Drive Shaft Housing and Gear Case Separation
Drive Unit Gear Ratio Identification
All drive unit gear ratios are identified on each drive in two places. It is important to note the
ratio of the drive unit before proceeding with any repairs. The first place to look is on the
decal on the port side of the drive housing. It will have a number such as (1.50R) and then
the seal number. The second place to look will be on the universal joint splined yoke. It will
be identified with a letter such as (F). This method is explained in the following chart. This
will be true for new or un-tampered with drive units. A drive unit could have had the gear ratio
changed for high altitude, which would void out any application of the following charts. The
gear ratio then would have to be determined by counting the teeth on the drive gear and the
driven gear in the drive shaft housing and using the following charts for reference.
Bravo One
U-JOINT IDENTIFICATION
RATIO U-JOINT SHAFT MARKING
1.65:1 C
1.50:1 F
1.36:1 H
NUMBER OF TEETH PER GEAR - DRIVE SHAFT HOUSING
RATIO DRIVE DRIVEN
1.65:1 23 30
1.50:1 27 32
1.36:1 27 29
Bravo Two
U-JOINT IDENTIFICATION
RATIO U-JOINT SHAFT MARKING
2.20:1 C
2.00:1 F
1.81:1 H
1.65:1 T

NUMBER OF TEETH PER GEAR - DRIVE SHAFT HOUSING
RATIO DRIVE DRIVEN
2.20:1 23 30
2.00:1 27 32
1.81:1 27 29
1.65:1 27 32
1.50:1 27 29
Bravo Three
U-JOINT IDENTIFICATION
RATIO U-JOINT SHAFT MARKING
2.43:1 N
2.20:1 K
2.00:1 B
1.81:1 G
1.65:1 C
1.50:1 F
1.36:1 P
NUMBER OF TEETH PER GEAR - DRIVE SHAFT HOUSING
RATIO DRIVE DRIVEN
2.43:1 23 30
2.20:1 23 30
2.00:1 27 32
1.81:1 27 29
1.65:1 27 32
1.50:1 27 32
1.36:1 27 29
Bravo XZ
U-JOINT IDENTIFICATION
RATIO U-JOINT SHAFT MARKING
1.50:1 Z
1.36:1 T
DRIVE SHAFT HOUSING
NUMBER OF TEETH PER GEAR - DRIVE SHAFT HOUSING
RATIO DRIVE DRIVEN
1.50:1 27 32
1.36:1 27 29
Bravo XR
U-JOINT IDENTIFICATION
RATIO U-JOINT SHAFT MARKING
1.50:1 R
NUMBER OF TEETH PER GEAR - DRIVE SHAFT HOUSING
RATIO DRIVE DRIVEN
1.50:1 16 19
Diesel Bravo One X
U-JOINT IDENTIFICATION
RATIO U-JOINT SHAFT MARKING
1.65:1 C
1.50:1 F
1.36:1 H
NUMBER OF TEETH PER GEAR - DRIVE SHAFT HOUSING
RATIO DRIVE DRIVEN
1.65:1 23 30
1.50:1 27 32
1.36:1 27 29
Diesel Bravo Two X
U-JOINT IDENTIFICATION
RATIO U-JOINT SHAFT MARKING
2.20:1 C
2.00:1 F
1.81:1 H
1.65:1 T
NUMBER OF TEETH PER GEAR - DRIVE SHAFT HOUSING
RATIO DRIVE DRIVEN
2.20:1 23 30
2.00:1 27 32
1.81:1 27 29
1.65:1 27 32
1.50:1 27 29
Diesel Bravo Three X
U-JOINT IDENTIFICATION
RATIO U-JOINT SHAFT MARKING
2.43:1 N
2.20:1 K
2.00:1 B
1.81:1 G
1.65:1 C
1.50:1 F
1.36:1 P
NUMBER OF TEETH PER GEAR - DRIVE SHAFT HOUSING
RATIO DRIVE DRIVEN
2.43:1 23 30
2.20:1 23 30
2.00:1 27 32
1.81:1 27 29
1.65:1 27 32
 

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the XR drive all of them have the same upper gears 16/19, the lower is the gear ratio factor. 15/19= 1.50, 15/17=1.34, 17/18=1.24. Imco does not stamp the lower unit unless you buy a new complete unit and only sometimes will you find the gear ratio stamped on the trailing edge at the top just below where the upper cav plate would sit. this is only for when they build lowers for stocking and they can know what it is.
 

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Discussion Starter #4
Boat Teck and HulShot thank you for your response that is the kind of information I was looking for. :)devil
 
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