Re: my bravo outdrive gear experiment
 

Tore lower the rest of the way down,gears look close to perfect still. These gears have as many ,if not more,wfo passes on them then the others I have tried on several sets of gears combined(plus the 5 blade really helped to push them to their limit)although they have less total hours.I am going to re-assemble the lower with my other max worx xr style prop shaft and carrier and try to run them some more although it seems our warm weather is gone for the season. My next step is to go back go back to 80/90 synthetic oil (to free up some speed plus see if heavier oil lengthened the gear life)and see what they look like in another 10-20 hours,Smitty

Re: my bravo outdrive gear experiment
 

Here are various pics of the lower gears. The newest treatment I contracted to have done looks like the ticket to longevity. Now after all this experimenting maybe I will be able to implement it in a way that will help my paying cutomers :D Smitty

Re: my bravo outdrive gear experiment
 

Smity thats a weird place to break isnt?


Pantera28-650HP so thats about 200lbs heaver that a stock bravo set up

Re: my bravo outdrive gear experiment
 

Smitty,
Looks like you may have a lower gear recipe. It would be interesting to see what the next set will do with the same treatment. How long do you think this set will last with what you now know?
Have you had any upper problems ever?
Dwight

Re: my bravo outdrive gear experiment
 

Whitey,I am estatic when I look at these lower gears.They look like they should last 4-8 times longer than what I have been accustomed to. I been saying oem prepped gears last me 20-40 hours but when I look back the stock set I ran while waiting on my current set to return from this newest treatment (after the hardened ones lasted 17 hours) were getting galled and starting to deteriate already and they didn't have ten hours on them. I was basing my hours on the set of gears I ran until the verge of complete failure-(see the pic). These latest gears have as much wfo time as all the other sets I ran this summer COMBINED and they barely have any marks on them,on top of drive being torqued from the 5 blade SO HARD IT SHEARED OFF THE PROP SHAFT!!!. My next step is to re-assemble my lower in next few days,then try running as much time as possible before the water turns to ice with 80/90 synthetic instead of 75/140 to see if the thicker oil is helping them live or if they can be ran with the thinner stuff and still live. I have a few local customers that trust me to do there drive work (I have all the neccesary tools and have been rebuilding rear ends and transmissions for 20 plus years) who I am going to try to sell on treating their gears (although most these guys are not running the kind of power I am).
As far as uppers,I have been a dealer for Max Machine worx since the xr gears first came out and they did have some problems with the first stuff they sold. I initially ran my bone stock 2000 bravo for about a season with my blown 502,i sheared the floor out of a stock gear when I added headers and went to a 28 pitch prop. At that point I bought all the upgrade parts Max worx was selling at the time-shafts,modified xr gears,a few different bearings that were supposed to be better. I sent my upper to them and had there steel tower installed,got it back and put the other parts they sold me in it and my lower. At that point I bought most the merc tools too. After a year they came out with a better short shaft that goes in the cone clutch,a better middle coupler,a billet seal retainer and a humungous aluminum cap that was supposed to act as a heat sink. When I installed these parts I flipped the top gear to the bottom and bottom to the top to even out the time each gear had on it (right hand rotation). First time out I sheared the floor out of the lower gear in the upper just like the stock ones do,I was beating the pizz out of it when it happened.Turns out they were machining the xr gears for their heavier duty caged bearing and in-advertently had weakened them. I installed their newest xr upper and lower gears (which weren't machined out) and there current heavy duty bearings (i think that was in 02). Later that season I tore drive down to inspect it before going on a long vacation and pinion gear had scallops in it about .005 deep so I replaced just it (the original was one of the early soft xr pinion gears :( ). Those same gears have been in my drive since then (5 seasons). The only part I have broke (other than the lower gears eating them selves up and the original max worx prop shaft breaking the other day that had 300 plus hours on it) was one of their vert shafts that I sheared off driving like a retard 4 years in 2003 (I was hole shot-ing my boat over and over again from almost a dead stop showing off). I still believe they have the very best upgrade parts that can go in a bravo housing,now that I have found a way to get the lower gears to live a more reasonable time, I expect my boating to be more enjoyable. I don't plan on trying to turn any 5 blade props though with 950 plus ft lbs of tq though because I feel it will just break something else :p ,Smitty

Re: my bravo outdrive gear experiment
 

Smitty,
With what you have done I would think someone running a stock set up would never wear out the drive. I too am hoping to hit the water a few more times before the ice. I have B1 lower case coming from Chris at Sterndrive spec. Hopefully it will be here in the next week or so. Dwight

Re: my bravo outdrive gear experiment
 

Interesting work Smitty. :cool: Are you using a solid driveshaft hookup with that Stellings box? I'm convinced that the Imco torsional driveshaft plugged into a standard Merc coupler is better for drive life. Other than that, it looks like you have this drive thing figured out. Do you think that 2 of your drivetrains would live in a Black Thunder?

Re: my bravo outdrive gear experiment
 

Ian,I am using a solid driveshaft but this box has netted negative results all the way around so its coming off and a heavy duty coupler is going back on.These lower gears failing seems to be a problem with single engine boats with big power. Zt260,gpm,others and me have ran into this with 800 plus hp motors,everything in drive seems to hold up for most part then the lower gears start going away after long wfo passes,I think this treatment process is a good solution. In my case the Max worx parts in the upper have been holding up a very long time. In the bigger twin engine boats that are 8000 lbs plus ,even with less power, lower gear failure doesn't seem to be the case,most of us single engine guys run 1.50 ratio gears (the least durable ones),most the big boats run 1.36's which seem to be more durable). Them guys can't get ANY upgraded bravo drive to last,they blow max worx uppers right apart,shear off vert and prop shafts that are the best material out there,etc,etc. When I run a 30 labbed on my boat and I'm going 60 mph and wack the throttle,my boat rockets to 85 mph in less than 10 seconds.When I tried the 5 blade and I wacked the throttles at 60 or 70 mph,boat strained real hard and built up speed about 1/3 as fast,alot like the way a heavier,bigger boat accelerates. Sure enough after 1 day of testing that prop I broke a prop shaft and my boat has never broke one before.Your boat has had very few drive problems for as big as it is but I bet if you added superchagers like you have talked about or went to 5 blade props or both :eek: you would start disentegrating drives. Max worx advertises guys with 1000 plus hp boats using there drives but they are 4000lb to 6000lb single engine boats (and they also go thru lower gear sets). You don't hear them saying alot about 800 hp 12000lb boats though,Smitty

Re: my bravo outdrive gear experiment
 

I been busy but here are a few pics of some batches of gears I have had prepped and treated for some oso'ers,local guys,mr gadgets and myself.Anyone interested let me know,I will have a few sets of new lower gears on the shelf that are cryoed and treated soon for anyone wanting to upgrade. Heres some xr uppers and pinions,trs gears,lower gears and even a set of 12 bolt gears I had done,they all looked beautiful after the gear processing,Smitty

Re: my bravo outdrive gear experiment
 

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