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Speedmaster#3 Gear ratio for 38' Coyote

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Old 03-20-2007, 11:38 AM
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Default Speedmaster#3 Gear ratio for 38' Coyote

Hi All,
We were in the process of doing some general maintenance and noticed some milky colored fluid coming from one of the drives.
We decided to take the drives off for pressure testing to find out if the lower seal was leaking.
Upon further inspection after removing the drives we noticed that one of the teeth on the upper gears was broken on the port side.
So, we now are going to replace the gear but we also have the option to switch the gear ratio on both drives but I'm not sure what the overall performance will be. I thought maybe some of you would have some additional advice on what the best gear ratio will be for our setup.
Right now we are running 1.68
So we can replace the one upper back to original of 1.5 or change both uppers to 1.35 giving us a new ratio of 1.5.
I have been told that with the new gear ratio we will get better top end but getting on plane will take a little longer. I have also been told that normally with the 1.68 gear ratio was made for heavier boats with not enough horse power to more easily get on plane.
We have twin stock 496 hos staggered 18 OC. running 3 blade 14x26 cleavers.
Right now our top end is 55mph I have been told that with the setup we have we should be somewhere in the mid 70mph range?
Your input is greatly appreciated.
Thanks
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Old 03-20-2007, 12:22 PM
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if you are in your correct rpm range, then a gear change will not help your top speed. and I am biased, I have a 1.5 upper gear set for sale? do you have the 1.35 gear sets?
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Old 03-20-2007, 12:48 PM
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Bigyellowcat,
I am at the correct rpm range only because I am running the wrong props is my guess. my rev limiter hit when I try to trim the motors and I feel like I'm making a whole lot of noise and not going anywhere.
Think there is to much prop slip...
If I decide to go with the 1.5 upper then I will only need 1 for the side that has a broken gear. Maybe you could send me a pm or post how much you are asking for your set?
Thanks.
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Old 03-20-2007, 04:15 PM
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If you could get the props to hook up, they would probably be the right pitch for the 1.68 ratio. 5000 rpm would equal about 70 mph. You would be doing good to go that fast with that small of engines. Most people running Speedmasters are running 4 blades of about 16 inch dia.
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Old 03-21-2007, 06:56 PM
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I would think you could use more prop diameter to decrease prop slip. I was running 17.5" x 24" props on an 18" centers with #3's & 1.62 ratio in a 34' Coyote. Boat ran 71 mph at 5450 RPM in flat water.
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