Bravo 1 Built With Wrong Gears?
05-04-2018, 10:46 AM
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Bravo 1 Built With Wrong Gears?
I have a 1995 Hallett 240 with a 525SC and a 0F5 Bravo One. The entire power package is bone stock, 465 hours. 3 seasons ago, the bronze shift ring on the reverse gear fell off and left me stuck in reverse. I cleaned it, applied new adhesive and pressed it back on. Last season, it fell off again (end of Labor Day weekend so not too bad). Apparently, the rings stretch, and there's no press-on replacement. So I'm buying a new Merc gearset. My drive has 1.50R stamped into the decal on the port side. About to spend $2000 so I double check the ratio by counting the gear teeth. 27 pinion, ok. 29 driven. Count teeth 3 more times. 29. That makes my drive a 1.36 ratio. What? I break out the folder full of service receipts dating back to 1998. No major drive service mentioned, just routine maintenance.
Is it possible Mercury assembled the drive with the wrong ratio? Anyone ever seen that before? Maybe someone swapped the gears, but I thought they moved away from the pressed shift rings shortly after my drive was built... anyway, the boat has always been a bit sluggish out of the hole, so I'm thinking I will change to the 1.50 gears (XZ) anyway. I know that will stress the lower a bit more, but I'm more worried about tower flex.
Oh, and I know my gears are the older, thin floor ones because I mic'd the shims at .094 as is stamped on the upper. Any comments would be appreciated.
Is it possible Mercury assembled the drive with the wrong ratio? Anyone ever seen that before? Maybe someone swapped the gears, but I thought they moved away from the pressed shift rings shortly after my drive was built... anyway, the boat has always been a bit sluggish out of the hole, so I'm thinking I will change to the 1.50 gears (XZ) anyway. I know that will stress the lower a bit more, but I'm more worried about tower flex.
Oh, and I know my gears are the older, thin floor ones because I mic'd the shims at .094 as is stamped on the upper. Any comments would be appreciated.
05-04-2018, 12:01 PM
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My drive said 1.5 too. Both my mechanic and I had the drive off at various times and it wasn’t until I cleaned it up for painting that I found someone scribed 1.65:1 on it. You never know what people do but it sure did explain my terrible slip numbers.
05-04-2018, 02:22 PM
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Haha, you just reminded me of the conversation I had with BBlades.... something like 7% slip? Must have a tacho problem!
05-04-2018, 05:27 PM
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I've been running a Hydromotive Quad 23P but that's a prop that prioritizes top-end speed over holeshot. The boat came with a Merc Bravo 1 24P that had been re-pitched to 23. That one worked ok I guess. A heavy, single engine, deep vee boat will never be a dragster, but I always felt for 500+hp it was working hard to get up and run, especially with props in the early 20s range. When I plugged in my numbers to a prop calculator, I used the 1.50 ratio the drive is labeled with, which explains why I was getting impossibly low slip numbers... the prop was actually turning much faster.
As far as the pairing being common... I would have no idea about that. I'd imagine Merc would assemble any combo a builder asks for. I guess my question is, would my Hallett benefit better from a 1.50 gearset? From what I've been reading, turning a larger prop slower is more efficient that turning a smaller prop fast.
As far as the pairing being common... I would have no idea about that. I'd imagine Merc would assemble any combo a builder asks for. I guess my question is, would my Hallett benefit better from a 1.50 gearset? From what I've been reading, turning a larger prop slower is more efficient that turning a smaller prop fast.
Last edited by esteinbrenner; 05-04-2018 at 05:30 PM.
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05-06-2018, 12:02 AM
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05-07-2018, 11:44 AM
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I've been running a Hydromotive Quad 23P but that's a prop that prioritizes top-end speed over holeshot. The boat came with a Merc Bravo 1 24P that had been re-pitched to 23. That one worked ok I guess. A heavy, single engine, deep vee boat will never be a dragster, but I always felt for 500+hp it was working hard to get up and run, especially with props in the early 20s range. When I plugged in my numbers to a prop calculator, I used the 1.50 ratio the drive is labeled with, which explains why I was getting impossibly low slip numbers... the prop was actually turning much faster.
As far as the pairing being common... I would have no idea about that. I'd imagine Merc would assemble any combo a builder asks for. I guess my question is, would my Hallett benefit better from a 1.50 gearset? From what I've been reading, turning a larger prop slower is more efficient that turning a smaller prop fast.
As far as the pairing being common... I would have no idea about that. I'd imagine Merc would assemble any combo a builder asks for. I guess my question is, would my Hallett benefit better from a 1.50 gearset? From what I've been reading, turning a larger prop slower is more efficient that turning a smaller prop fast.
I also run 1.36s, I have been told that a 1.50 setup can be faster but I have never personally seen actual proof of this vs the 1.36 - main thing to me is prop selection and I have no problem finding the props I want or need for my setup in the 24-26p range. In my opinion it is all personal preference.
