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Thinking about making good TRS lower gears and shaft.. Any interest.

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Old 05-22-2015, 09:11 AM
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Originally Posted by VoodooRob View Post
If you do them right, there is no shortage of customers. I have to replace upper and lowers on starboard this year. Replaced entire port drive last year. Boat has 300+ hrs, can't be mad but life would be better if I knew the new parts were better quality and durability.
We've been making gears for almost 50 years so I know we will get that part right. What breaks first on the XR uppers or lowers? and is it case deflection breaking the gears or the gears themselves?
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Old 05-22-2015, 10:18 AM
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Sounds like you are on your way to becoming a rich man....lol Seriously though, deflection does play a part in some cases but the most significant factors I see (and I'm not a drive expert but I am an engineer) are the physical gear size AND material composition / forging process. The breakage seems to be somewhat dependent on several factors such as hp, tq weight of boat, # of prop blades, and drive heights to name a few. The upper gear sets are more expensive and since now the lower gear ratio determines the overall drive ratio, I would probably start off making the standard XR upper 15/19 gears if it was me. Their are some guys on here that have done a lot of testing and some gear analysis maybe they will chime in.
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Old 05-22-2015, 10:31 AM
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Originally Posted by Cobra100+ View Post
Sounds like you are on your way to becoming a rich man....lol Seriously though, deflection does play a part in some cases but the most significant factors I see (and I'm not a drive expert but I am an engineer) are the physical gear size AND material composition / forging process. The breakage seems to be somewhat dependent on several factors such as hp, tq weight of boat, # of prop blades, and drive heights to name a few. The upper gear sets are more expensive and since now the lower gear ratio determines the overall drive ratio, I would probably start off making the standard XR upper 15/19 gears if it was me. Their are some guys on here that have done a lot of testing and some gear analysis maybe they will chime in.
Good points. I was also thinking, since gear noise is pretty much a non-issue in high horsepower powerboats, my options open up for a stronger gear design that might be a little noisy compared to the stock helical cut gears.
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Old 05-22-2015, 10:44 AM
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XR gears are already straight cut.
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Old 05-22-2015, 10:49 AM
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XR gears are already straight cut.
Ahh okay, TRS are not.
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Old 05-22-2015, 04:41 PM
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If you build a TRS lower, make it a sportmaster shorty style. I'm sure a lot of people would stick with the TRS if they could buy a stout lower and gain some performance with the shorter drive. I know I pry would have!
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Old 05-22-2015, 07:12 PM
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^^^^^ a+
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Old 05-22-2015, 07:27 PM
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PArt of the gear problem, I believe is this:

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In the gearing industry, gears are lubricated and cooled by various methods. At low to moderate speeds and loads, gears may be partly submerged in the lubricant which provides lubrication and cooling by splash lubrication. With splash lubrication, power loss increases considerably with speed. This is partially because of churning losses. It is shown that gear scoring and surface pitting can occur when the gear teeth are not adequately lubricated and cooled.
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Old 05-22-2015, 09:13 PM
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Originally Posted by Rbesola View Post
If you build a TRS lower, make it a sportmaster shorty style. I'm sure a lot of people would stick with the TRS if they could buy a stout lower and gain some performance with the shorter drive. I know I pry would have!
+2, I actually really like my TRS drives. 1 failure in 14 yrs isn't to bad, but I now have 2 sets of gears as spares.
Wait, that would hopefully be -2". lol

Last edited by Rookie; 05-22-2015 at 09:16 PM.
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Old 05-25-2015, 09:25 AM
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Well are these ready for shipment ??? I WILL TAKE TWO OF THEM!!!!!!
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