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.

My boat has a 28p all ready on it and with 3-4 ppl and full tank of fuel hops on plane in 20-25 secs. With 2 PPl full of fuel in under 10seca. Loaded down with 7ppl, coolers, and fuel it take awhile but never blew a drive.

I have a shorty lower and I drive on the Great Lakes. No one can be perfect on the throttles and my prop leaves the water often. I don't slam the throttle out of the hole but I don't drive the boat like a ***** either. Let's see you make a Bravo X live in 4' Lake Erie slop.

Yet! I was saying the same thing until the end of last season. I was cruising along in calm water at 70mph and put the throttles down, hit about 80mph before it started slowing down. My gears now need dentures,

It can be done, although you have to baby the boat a lot. I am running 700 N/A power through my XR's and have done ok with them. Your pocketbook will teach you really quickly how to drive the boat, and it can get expensive fast. Coming on plane slowly, respecting rough water and easing into the power has kept the breaking points to a minimum. Have your drives pulled every winter and gone through. That will help locate a catastrophic failure before it happens, but even that doesn't provide any guarantees. It also helps to find a drive guy you can trust, get to know him and let him know if he takes care of you, it will make a frequent customer for the life of the boat.

There are many scenarios here, but the common theme is to take care. I own a smaller 22 Donzi ZX with a Bravo 1 that had over 500 hours with a Procharged 502 making somewhere around 675hp. I now have 50-ish hours on a N/A 540 pushing a little over 600. Drive was gone though during the repower and it looked very good. In my case, taking care has been the key even with WOT runs every time out. (Lake use) I can only assume that my time is coming, but I'll wait until it gives out before I drop any $$$ on a different drive.

Sounds like most of you guys are correct, it's how much weight you have to push vs HP doing it.

Load the boat up with people or a heavy boat has the biggest affect, especially when you try to over come it with horse power.

Bye Bye drive

I've got 2 or 3 extra Bravos I plan to post in Swap Shop this weekend.

PROBLEM SOLVED. :lolhit:

The max power a drive will see getting on plane is the max TQ the engines make (if its hooked up).
The biggest death blow is the torque spikes leaving and re-entering the water.
In my opinion getting on plane hard is not a big deal.

We have plenty of broken Bravo's to go against that theory. Several of these boats where near impossible to go airborne in our waters.

Obviously airtime will hammer the drives...however, that is not what I'm arguing.

=================

Edit in:
BTW. I can prove it for you. I'll come over, drive your boat, and show you.

LOL. Okay, more like LMAOF.

I agree. I think running 110 weight oil helps. Never had luck with Merc stuff.

One thing I`m certain of is if i gave you my boat for a day and told you to try to break the 4`s only getting on plane you`d be tired at the end of the day but the drives would be fine.
Before I got good props a 2 minute 5000rpm burnout was standard procedure :angry-smiley-044:

Can you say burnout , slippage ,not hooking up, not loading drive etc. just saying !

Running 950+ through a bravo xr. Rebuilt after about 100hrs. Gears worn out. I Don't baby it coming on plane just don't do anything stupid. Half trim at 60 and hammer it, excelleration is amazing. Haven't blown one yet,,,,,,,,, yet.

what size prop,# of blades and gear ratio?

I babied my fully upgraded imco SC drives behind procharger 500efis in the Baja for years. Rebuild drives every season around 30 hours. Became used to the boats speed and sick of driving like a grandma. So started driving like i was in a race truley enjoying owning a 100mph boat! harder and faster I ran her the longer the drives started to last. Crazy I know.

The science to me is max torque is max torque. Cruising speed with the boat dragging through the water WEARS the drive out. Most engines are making about peak torque at cruise speed. Getting on plane does not break a drive. Just plain using the drive prematurely wears it out. Simple.

Now getting air, especially small blips, will break a drive

Getting on plane, cruising, or driving fast will not make any noticable difference in how long a overpowered drive lasts.

I can one up CAB on the XR.

350hrs of 1250ft lbs heavy diesel torque into a 2007 1.26:1 XR spinning 5 blade of 35 or 37 pitch pushing 5300lbs. Could blow a 4-blade 32 bravo out of the water with ease.. Only known mod, IMCO output shaft. Stock shaft failed and was replaced before I purchased the boat. Besides a shifter lever snapping, no other issues. Opened the top a couple time to inspect, but never pulled the lower in 5yrs. Still on the water todayd.

That said, I did torque limit the power last year to about 850ft lbs below 2400rpm when I noticed the upper swivel pin showing wear. It only saw BIG water twice in it's lifetime with major air multiple times then, that being key in my book. Smooth water, 60 mile runs for lunch was a normal day.

5 blade hydromotive p5x 30p with 1,36 and -2 sportmaster

I'll agree 100 percent on the hp doesn't break drivetrain torque does. I truck pulled for years with 700hp all the way to 1100hp cummins. I never broke anything at redline. Only time I broke driveline parts other then bouncing was when the weight of te sled would suck the power down and I would get under the turbo in the peak torque range. Then you could really watch the parts fly. So I am kinda on the theory where cruising around in the peak torque range can be just as bad as topped out.

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......

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.

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.

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

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.

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)

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]

Only sixes I can afford are on the beer aisle.

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

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!

I've read a bunch of theories here and other places on what cause some of these to fail behind 525's, while guys like myself push them far beyond rate hp specs without issue. My personal theory is aluminum fatigue over long time, allowing case flexing to higher clearances. Or too much air time on heavy boats.

Has anyone else ever wore out a SS XR prop hub before the drive? To where you thought the shaft was bent causing prop wobble.


God knows I was never easy on my XR. Multiple groundings, logs strikes, even wrapped a steel cable up and stalled the engine at cruising speed once. But with over 350hrs on the meter, reliability speaks for itself.

Some personal GoPro examples at 330hrs right here:

http://youtu.be/Dhk4eA-Qmgs?list=UUW...mldgz7bXn_xcgg

Well from 8 pages of reading I've gathered it WILL break. Just when depends on how lucky you are.

That's exactly what our's (handful of boats - minimum of a few times each) did and probably a billion other bravo drive owners.

These forums where lit up for years with people doing the same thing.

Now not as much, but more people now-adays have better drives (min of XR's and of course tons of aftermarket) than stock regular Bravo merc stuff. I said more.
I don't know how the people on this thread have kept there stock drives together.

Get a left hand prop if you running a right hand. Then reverse will get u back to the dock going forward. Not a fix for the problem but will help out getting home.

Think I'm just going to replace the upper with an imco scx and keep the sc lower. But wondering how much speed I will lose spinning those bigger gears. Although I will have piece of mind knowing it won't break as soon as I find 10k laying around.
FYI I also have a pair of Gibson slip on mufflers which I don't actually need where I live but have run them before. Boat is a lot more quiet but it will NOT run over 98gps with the mufflers on. 102 with out. They seem to be robbing a lot of power!

Gibson slip ons for sale!!!!

You won't loose anything going with the scx uppers and the sc lowers , I did it.

Ok now that we've beat this topic to death got another question. My boat was kinda hard getting on plane last year with the 28p. The performance shop has every kind of prop you can ask for within reason. I can try as many as I want for free. They want me to try a 30 or 31 to start next season. My question is what about going to a 5 blade prop? From what I gather it is harder on your drive but you can get on plane faster. What's everyone's experience between 4 and 5 blades? What do you lose and or gain going to a 5 blade from 4
Blade.

I didnt see much diff getting on plane, but mine doesn't take much to get up,2800-3000 it will pop up on plan,

i would think it would help you though, but unless you went up in power going larger/pitch prop would hurt getting on plane,

I went from 30p 4blade to 28p 5 blade and it dropped/lost about 300rpm