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-   -   Bravo 1 behind 750hp? (https://www.offshoreonly.com/forums/drives-lower-units/320283-bravo-1-behind-750hp.html)

offshorexcursion 12-18-2014 10:45 AM


Originally Posted by SB (Post 4236497)
That's where your science is flawed. Max (Peak) torque can only happen when your throttle is wide open.

Cruising at the same rpm your motor makes peak torque at full throttle has nothing to do with each other, other than the rpm.

So, don't let that keep throwing you off.

Yeah my wording last night at 4am wasn't perfect. BUT an overpowered bravo drive at cruise speed is making MORE Torque then the drive can handle. So driving around slow with the boat draggin in the water is STILL wearing the drive out. All while not even enjoying the full potential of the boat! That's where the majority of people spend their time, at cruise speed. You can baby the boat getting on plane, not jump it in the air, and not drive fast often, and you WILL STILL BREAK a bravo based drive. So there must be something more to my statement......

offshorexcursion 12-18-2014 10:48 AM


Originally Posted by SB (Post 4235791)
You guys are wussies.

We used to brake Bravo's for lunch with 502/415hp engines. BTW: Fresh water here. Very fresh.

Common demonitaor between the group of boats busting Bravos - the boats where always packed with people (8+) and the boats where planing when the gears broke. 3 and 4 blade props. No one had the nutz to try more blades.

NONE of my friends nor myself have broken a bravo style drive while getting on plane........

Getting on plane "normal" does not break a bravo drive. Getting on plane super slow, and putting X amount of torque through the drive for two or three times as long could actually be worse.

sutphen 30 12-18-2014 11:03 AM


Originally Posted by CAB (Post 4236450)
5 blade hydromotive p5x 30p with 1,36 and -2 sportmaster

thanks
5 blade 32 pitch full merc prop,1.5 gears and drive shaft 1/2" above bottom of my boat.all ocean driving and not easy on the throttles at all.800-900tq.
I usually break a tooth off a gear(xr) every 50hrs or so.this last time I pushed the spanner nut off the case,,may be stripped out.have to look at it this winter.

r015 12-18-2014 11:20 AM


Originally Posted by CAB (Post 4236450)
5 blade hydromotive p5x 30p with 1,36 and -2 sportmaster

How did that prop compare to a bravo1, sounds like good match?

MILD THUNDER 12-18-2014 11:41 AM

75w90 is too thin IMO for highly stressed gears seeing high temperatures. I been running 75w140 . lost no speed and no more fuzz on magnet between fluid changes.

Most heavy duty applications in automotive , trucking, industrial, have been moving towards the 75w140 gear oils from what I've seen.

cig92 12-18-2014 03:14 PM

if you are set on a bravo there is one other thing you can do to help your situation, use a 4 blade prop instead of a 5/6 blade. the less blades, the less bite. it will save on the "load" that gets put on the drive every time you re-enter the water. slip can actually be a good thing. you will lose in the cruise speed are but most of the time gain in the top end. generally speaking, the less blades, the faster. i know this doesn't apply to all boats but does so with more conventional bottoms (non step, single step)

Velocity Vector 12-18-2014 04:21 PM

1 Attachment(s)
I agree with everyone's how too's on the bravo, I fixed mine this way. My excuse was ---- we're gona need a bigger boat.


[ATTACH=CONFIG]534570[/ATTACH]

Cole2534 12-18-2014 05:28 PM

Only sixes I can afford are on the beer aisle.

CAB 12-18-2014 06:31 PM

My boat is faster with the hydromotive than with the mercury maximus or the bravo one.

La/stryker 12-18-2014 11:47 PM

I'm having a slightly different bravo 1 failure. I have a 2001 htm ss 24 carbon top cap with the original 565 na motor 650hp with 1050 Dom carb. Had it for two seasons with no problems on river and lake calm water(about 10hrs a year) bravo 1 upper imco sc lower never had chips on magnets just some very minor fuzz. Motor had been freshened before I bought it but no changes. I had to replace the heads because the started leaking small amounts of water thru the jackets and into the cylinders. It was not head gaskets or leaking headers I checked that first. with the new heads smaller comb chambers not sure what the compression ratio is now but getting 200psi plus or minus 10 psi and some cylinders have minor water damage cause heads would leak just sitting in garage. I'm not sure what the current hp is but picked up a solid 2mph, Guessing 675hp
After head change I broke the floor out of the upper fwd gear planing out but it was with about 3/4 throttle takeoff. 30 pitch 4 blade brave prop 1.5 gears. I had it fixed and lasted about 10hrs till next summer when I went to pass another boat I went full throttle at about 4000rpm and about 70mph around 80 mph it broke the floor again and almost over revved, glad my hand was on the throttle! I have replaced the same gear again, exactly the same break. It's like the boat goes into neutral. Reverse still works afterwards its only fwd gear floor. Now I'm scared to run it had cause its a long trip to the boat ramp in reverse if I can't find a tow. Am I missing something? Anyone else had this problem? Boat runs 102 GPS btw and still never had anything but fuzz on magnets and broken gear teeth look fine, no visible sign of wear. Wtf so many people running more power with heavier boats with better luck!


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