Dkahnjob

I recently purchased a Formula 353 with 600's and Bravo XR drives. On inspection there was metal on the drain plugs so we tore down both drives and there was some signifigant gear wear. We are going through both drives.
The drives have about 100 hours on them and since I just got the boat I really don't know much history as far as how hard they were run or when or if the drive oil was changed. I do know that there weren't any drive showers, but I have added them now. Just wondering is this typical or if I am easy on them can I expect better life out of the drives than this?
What are your experiences?
Thanks in advance.
Dave

VoodooRob

I have the same 600SCI/XR set-up as you in an 07 38 Fountain Full Stagger. The drives seem to need going thru every 100hrs, they both have been done twice on our 220 hr boat. I also had an 05 353 with 525/XRs and the drives lasted 300 hrs before rebuild for comparison. Seems the 600s really max the XRs out, Merc should have only offered the NXTs. Being smooth getting on plane, applying throttle in a ramp up style to achieve top speed, and throttling correctly when in the air will definitely help the XRs live a longer life.
Also my boat didnt have drive showers on it when I bought it, they are cheap insurance don't understand why the previous owner didnt run them. Worst scenario the case will run cooler, best case oil will drop some temp. I have run with and without showers and case temp difference was substantial.

Keith Atlanta

Try heavier oil like Amsoil Severe Gear 75-110 or 75-140, yeah, you lose 1 MPH on top but they dont chew up the gears as fast. Some guys are getting better results with X gears as well.

There are several ways to get more life. Several threads about it - depends on what works best for you.

Dave M

I would think about upgrading to IMCO's or something else if it turns out you will be laying out significant $$ to get your drives fixed. I've heard pretty good stuff about All American Drive Service upgrades.

Dkahnjob

Thanks for the info guys.
My mechanics said the drive showers will lower opperating temps by as much as 30*, that should help.

Keith Atlanta

That will help. But dont kid yourself. Its a band-aid on a flesh wound.

Things that helped me:
1. Choose an oil heavier than Mercury HiPo gear lube.I pump in 1 qt of 140 and fill the rest with 110
2. Aftermarket top cap with 7/16 studs - this made a big difference for me. I think the higher bolt torque makes a big difference.
3. Have someone that is competent rebuild it to real specs. Not some jackass that can rebuild a "bravo".
4. Good drive shower or aftermarket cooling system. The cooling system worked wonders but then your spares have to be drilled for oil lines.
5. Im seriously considering going back to X gears to see how they hold up.

Yeah, there are a few shops that can perform miracles but I cant see spending $7,000 on a Bravo XR rebuild. If you are going to drop 7-8 grand buy an SCX

fossil fuel

If you drive oil smells burnt/cooked after 20 hours your drive is not going to live. My NXT oil looked as good draining out as it did going in after 100 hrs, thus no failures. These big HP engines just are too much on gears the same size as a VW transaxle. Heavy boat and 100% load duty cycle. Imco has a beefier solution but $$$. I used to carry a spare XR in my pickup toolbox just to finish a weekend event.

Wilks

Install X upper gear set. Half the price of XR gear set

offshorexcursion

iTrader: (5)

Actually sounds average or better then many actually!

Just Drive your performance offshore boat like it's made to be driven....and enjoy it! or get a pontoon....driving like a grandma does minimal to nothing to increase the life of a bravo drive with over 400hp going thru it. Now don't confuse that with abusing and not maintaining.

Definitely plan on freshening evey year or two as early as 20-30hrs depending what the magnets show.

Or upgrade drives

articfriends

iTrader: (1)

100 hours is pretty good, 353 is a stout boat, 600 merc hp is same as 625-650 hp if comparing to any small shops dyno, so boat is going to eat bravos every 100 hrs. Are you running 5 blades,it accelerates bravo failures too.
Run heavy synthetic amsoil as suggested, it may stretch out the rebuild intervals. In general bravos fail because of many things:
A bearing starts to fail from high speed/rpm use prob caused by lube failure/temp/viscosity breakdown, this allows gear or shaft to run misaligned, gear teeth fail
Over loaded, ie heavy boat, 5 blade props, too much tq, lube is literally squeesed out from between the itty, bitty gear teeth, chews up, if let go long enough pieces get wedged thru teeth or metal gets in bearings then gears try to spread apart blowing housing apart or catastrophic failure
Catastrophic instant failure- too much tq/hp vs slip, at higher power levels you simply shear off a shaft or blow teeth as they are severely overloaded compounded by less prop slip ie 5 blades like maximus, etc. Water is 800 times denser than air, boat uses every last bit of power it can to get boat to its top speed. Thats why once boat is on plane babying the throttles but then holding it wide on top isnt going to increase drive life a whole lot.
Heavy duty towers, hd caps, stronger shafts, correct set up, extra oil cooling, thicker oil, will all help. In end though you still have a 10,000 lb boat with fairly torquey motors, waste 3500 to 10,000$+ every 50 to 100 hours or spend 25,000 or so once and upgrade, hard pill to swallow for sverage guy!