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Location: New Albany, Ind. | i have a 85 merc 175hp black max, will changing the gear ratio in the lower unit from 2:1 to 1.87;1 hurt my motor in any way or tear it up. i do realize it will change performance, should take off quicker and be little slower on full speed i believe. any help would be appreciated. thanks ron |
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Posts: 1663
Location: Kodiak, AK | As long as your rpms are up where they should be and you're not bogging the motor down too much, should be OK. Why are you swapping? |
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Posts: 49
Location: St. Croix River, Mille Lacs, | You might be better of playing with props a little more VS changing the gearing. Your local Mercury Dealer should be able to provide you with several blue demo props before you buy one, if not contact Mercury and they will fix you up. |
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Posts: 1663
Location: Kodiak, AK | I was thinking the same thing, which is why I asked why he was swapping....props are a bit easier to work with and swap and there's so much more in the way of variety. |
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Location: New Albany, Ind. | the reason i am changing is my old lower unit it needs to be replaced, hit a stump. the guy that is fixing it happened to have a good lower unit on a 150 hp black max, and he give me a good deal on it. the new one is 1.87;1 where as my old one was 2;1. just want to make sure it wouldnt hurt my motor, dont much care if it slows me down a little, like it better because it comes out of the hole alot faster. thanks ron |
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Posts: 3480
Location: Elk River, Minnesota | Hiya,
If you stay with the same prop pitch and diameter you have, I would bet your hole-shot will be slower....the reason: Your motor will be working harder to turn the prop. Granted, you are not dropping much, but when you hit the throttle, your motor is turning 1.87 times faster than the prop shaft is rather than 2 times faster than the prop. So...you will have lower RPM's across the entire throttle range with the same prop. Much of this is also dependent on your load, but overall, when you go down with the first number in gear ratio, your motor will have to work harder to turn the prop...
You might get lucky and not see anything significant, and depending on the load in your boat, you may see a slight increase, although I feel you might see a decrease overall.
Tough call, but if the lower unit fits, you shouldn't hurt anything at all mechanically..
Steve
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| Have you tried contacting Mercury directly to talk the matter over with them?
http://www.mercurymarine.com/utility/contact/index.php |
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