I'm running about 740 hp each through my XR/Sportmasters. What I've found at that power level is even if you are real careful on the sticks, (leaving water etc) to avoid breaking upper gears and tearing the upper yoke shaft assembly right out of the case, the lower gears just don't last very long. I typically get about 35 hrs on the lowers before they start to pit and see more metal on the magnets than I'm comfortable with. I then drain, flush and swap them from side to side, to get more life by running the back side of the lower gears and using up what would have been the reverse gear. By doing so, I've been able to get 70-80 hrs out of them before rebuilding. Make no mistake, they are garbage and a lot of work at higher power levels. If you're not doing your own rebuilds, it can get very expensive fast.

And yes, if I'm on vacation at another lake, (LOTO, etc) I always travel with a spare drive in the bed.

I am not saying that thermal shock is the only factor of a hot outdrive on long hard runs then within a blink of an eye gets dunked for 20 to 50 degree temp change just like that that is killing the Bravo. IMO it sure does not help. You have different forms of metals thru out the drive, all metals do not heat up nor cool at the same rates plus all metals do not expand and contract at the exact same rates rates,. Also the gear case is not as strong as you think it is that is supporting a lot of this nor is the top cap..

Also gear pitting is nothing new and can boiling down to Gear corrosion during the manufacturing process. There is forms of this called Pitting corrosion, Crevice corrosion and Intergranular corrosion.

Pitting corrosion is pitting or can be a form of corrosion that was already induced when the gear(s) were manu. It can cause failure by perforation while producing only a small weight loss on the metal. Also the pits are generally small and often remain undetected.

maybe but i still dont buy it, especially given the fact that on the opposing hot side surface heat is dumped into the case with arguably the same amount of heat transfer via gear oil. is the delta T net zero before and after submersion...probably not. is it enough to cause significant thermal expansion and contraction...eh i doubt it. just my opinion.

The smart thing to do is sell your bravos before they blow up and buy IMCO SCX drives
that way you will end up spending about what it is going to cost you WHEN you do blow the drives ( the first time)

after that its all good

Arneson

Ran boat last weekend and did mid 90s Taking the xrs off abd goin to b max uppers with imco 2 inch shorties How many mph will I loose y'all think

Curious as to the $$$ difference between the bmax and scx and why you went with the bMax. Let us know what you get for speed. What ratio were/are you running

BMX uppers only fix a poition of the problem. Bmax still use the dog schitt XR lower gears.

Just thought I would add this about my stock 425hp boat. The previous owner sent the drives to AADS and had them built to handle 700hp. I'm a stickler on maintenance and focus on keeping the boat in the water.

My port drive let loose last year despite what I know as proper driving, showers, and maintenance. However, I called AADS and honoring their 2yr warranty George said send it up because failures are rare and he wants to make it right. Lost a vertical shaft. He said oil and everything else was perfect and despite a quality party he felt it was a bad casting. Fixed it at no charge and sent it back.

Build it right. Build from those you trust. Due diligence with care and things can still happen. However, I'm glad the drives came from George and I'm set to run the water.

Great to hear that AADS stood behind the warranty.

Your story is the TRUTH about Bravo based drives, no offense to you personally.

Funny how some think 800hp is ok if you do this or that magic. But no matter what they WILL prematurely fail and or break!

This story proves how they break behind stock engines, then even when drives are UPGRADED to support 700hp they still break behind STOCK 425hp.