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800hp through an xr drive

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Old 04-07-2015 | 09:23 AM
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Originally Posted by ICDEDPPL
The truck will never see such scenario yet lets compare the size of the gears in my 3500 vs. a bravo







hmmmm.. one of these is designed to last a lifetime one is not
My point was we are conditioned to think drive failures should be accepted. These are very expensive toys, typically many times the cost of a new truck and there's no reason to accept such shoddy components but we do....
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Old 04-07-2015 | 09:31 AM
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Originally Posted by Smitty
What if there was a gearset available that for most applications up to 800 hp/800 ft lbs. that eliminated the"gear" failure of the XR ?? Would you all be interested in buying a set ??? What would you be willing to pay for them ????

And let's not be ridiculous with your answers about the cost.
i'd be interested,,but would need to know what the cost is gonna be.then whats the next week link,,upper shaft?lower shafts are pretty bullet proof
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Old 04-07-2015 | 11:05 AM
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Reading these post in making me laugh. When I was a performance boat newbie I was running 800 hp through a King Cobra drive without a care in the world. I don't know how the King compares to a XR but it never once gave me a problem.
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Old 04-07-2015 | 11:54 AM
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Man with all this Bravo hate you think a guy could find a Bravo cheap.

I'm worried about my poor little Alpha holding up behind my LS1, I would be as happy as a pig in **** if I could find/get a Bravo assy for a respectable price.
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Old 04-07-2015 | 08:38 PM
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Originally Posted by turbom700
Man with all this Bravo hate you think a guy could find a Bravo cheap.

I'm worried about my poor little Alpha holding up behind my LS1, I would be as happy as a pig in **** if I could find/get a Bravo assy for a respectable price.
The price is driven by demand haha! Lots need them to replace broken ones.
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Old 04-11-2015 | 08:10 AM
  #116  
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Originally Posted by Knot 4 Me
What about the vertical shafts that like to snap like twigs? And what to do about popping the top cap off the case when the drive walks those new gears up thru the roof? Or splitting the case at the top? Or the busted/twisted prop shafts? Then there are the Bravo props that throw blades like Frisbees! It never ends...
You missed the anemic gimbals they are bolted to!
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Old 06-15-2015 | 05:32 PM
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New to chiming in on the forum. I can resonate with all your experiences...especially the car analogy!

I'm an old drag racer who can relate to the rear end carnage in hot rods to serious drag cars. I have broken 12 bolts, 9" Fords,... until I finally graduated to Pro set up after being tired of breaking parts on the street and on the track. Many years later I feel like I'm back in the same RAT race with a heavy boat (13Klbs+) with a Whipple powered 525s (~750-800HP according to TEAGUE) in 2004 Donzi 38ZX Daytona in front of an XR drives!! I've been there and done that with breakage so I know and appreciate all OSO experience boaters comments. Heavy boat, big power means no launching hard and drive it easy out of the hole, and throttle up to planning speed before powering down gradually (grandma style at 90+mph ). I suppose its like driving your slicked up Big Block 871 blown Chevelle with a 10bolt! You gotta know your limitations with your set up. If you want to go big you have to pony up for the more expensive drives.. SCX seems like my next step. In the meantime, drive easy, frequent drive oil changes (trying Amsoil now), and easy on the stick.. Safe boating.
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Old 06-15-2015 | 06:30 PM
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The gears don't fail, the case fails them.

Think of meshing gear teeth like tires on the road, when the tires are loaded under torque you get thrust, when the tires are unloaded under torque you get slippage. Slippage causes excess wear and now it's time for new tires.

How does this relate? On involute gears the mating faces of the teeth ideally have minimal relative displacement, akin to a non-slipping tire. Now when the case flexes, and they do because everything is just bubble gum, the gear to gear relationship changes and the teeth slide across each other outside the typical wear pattern. This is why you see pitting on the teeth faces and once that face is wrecked it's all down hill.

#6 and #8 cases are massive, they're really really stiff compared to a Bravo. Arneson had the right idea, ditch the bevel gears and their crazy associated forces. Imco SC's use Merc gears to achieve better life spans, that displays what an improved case can do for gear life.

Last edited by Cole2534; 06-16-2015 at 06:51 AM.
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Old 06-16-2015 | 06:37 AM
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Originally Posted by Cole2534
The gears don't fail, the case fails them.

Think of meshing gear teeth like tires on the road, when the tires are loaded under torque you get thrust, when the tires are unloaded under torque you get slippage. Slippage causes excess wear and now it's time for new tires.

How does this relate? On involute gears the mating faces of the teeth ideally have minimal relative displacement, akin to a non-slipping tire. Now when the case flexes, and they do because everything is just bubble gum, the gear to gear relationship changes and the teeth slide across each other outside the typical wear pattern. This is why you see pitting on the teeth faces and once that face is wrecked it's all down hill.

#6 and #8 cases are massive, they're really really stiff compared to a Bravo. Arneson had the right idea, ditch the bevel gears and their crazy associated forces. Imco SC, and I believe Bravo Shop B-Maxes, use Merc gears to achieve better life spans, that displays what an improved case can do for gear life.
BMax uppers have massive gears compared to any bravo
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Old 06-16-2015 | 06:51 AM
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I stand corrected on those, will edit.
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