How to Determine Drive Ratio
 

I have a 28' Cat with a 525HP and Bravo 1 XR drive. Is there a way to determine my drive ratio based on drive serial numbers? Or, is drive ratio info normally noted somewhere on the drive or engine? I have the serial #'s, but the boat is currently hundreds of miles away in storage.

The serial numbers can tell you. You have to be able look up service history. Maybe someone on here can access that for you. With your set up I am going to say a 1.5 ratio. What size prop you running at what speed and rpm. That will give us a clue.

Post your serial #

I bought the boat in the fall and have only been out once and I'm not sure exactly where I was as far as RPM's, but I was only topping out at 70 MPH. The boat has a 24" pitch 4-blade Bravo 1 prop, a bit too small for me since I'm not so concerned with hole shot or acceleration. Below are engine and drive serial #'s and max RPM info based on my engine. I'd appreciate any help.

Max Wide Open Throttle RPM: 4,800 - 5,300
Rev Limiter RPM: 5,400
Drive #: W242929
Engine #: OM960795
Transom Assembly #: OW161C63

Your drive ser. # is OW242929 Bravo 1XR 150:1
Transom # is OW161063 not a C
Eng ser.# is correct a 525 EFI
Was reg. 04/18/08 in a Magic 28 model Scepter.
Looks like there hasn't been any warrenty repairs done or fixs needed for your ser. #'s

Your drive was born as a 1:50 and its been almost 4 years so somewhere along the line a gear change could have been done. Hope this info helps you.

Just as an FYI for you if you're interested, If you run the drive or T/A serial number only, you will miss most of the warranty repair work that have been/needs done (etc) to any of the three serial numbers, You always want to run the engine serial number even if you only have the drive or the T/A #'s to start with.

0M960795 has had some work done.;):)

Hope this helps.:)

Just ran drive #, Thanks for the tip

Very helpful, thank you. A gear change was probably never done, the boat only has a bit over 50 hours... I'm going to try a 28" pitch prop and see what I get for RPM's. Thanks again.

i would put it in the water and see what rpm's you get with existing prop. 4 inches is a big jump...