Keith Atlanta

Dont they still have to be lapped?

articfriends

iTrader: (1)

I worked on this very issue for the lower gears as those are what fail on my 1000+ hp boat, I have very little problems with bravo uppers. After testing various coatings/processes and heat treating of stock gears I found that cryo treating /iso- rem finishing seemed to make the lower gears last twice as long before cratering. The upper xr gears on the race boats they were tested on still spit teeth off in record time how ever. Me and RM BUILDER were looking into having lower gears made out of a different material, a single test set was going to be upwards of 5000- 10,000$ and a small production run was going to be 10 times that with no guarentee that they would even last a few hours, the upper gears are even worse to re-produce, the other Smitty was working on it, never heard what final outcome was but I do know that everyone wants someone else to foot the bill on getting something built, sell it to them at cost and guarantee it will last forever plus never damage their drive if it does fail, I stepped back from the project after spending a good amount of cash and time on it and just settled on cry/iso rem treatment with high end oil and that increases the life of a full out upgraded bravo by about double, Smitty

offshorexcursion

iTrader: (5)

Thanks for sharing Smitty!

Wolford

That's the problem, most boaters know nothing about manufacturing, nor do they have the multi million dollar equipment to produce a precision gear set. I have all of that, I own it, I can use it whenever I want, not on someone else's time. What I am saying is, I can machine the gear set from any material conceivable, however I don't have the expertise to digitize a set, and generate a working 3D model, with smooth surfaces adequate enough to generate tool pathes from. All I have is touch probe CMM's, that's not going to cut it as far as generating a perfect, accurate model. Need scanning laser, and someone smart enough to use it (very hard to find).

Kieth, I can achieve a RMS 8 finish with my Mori 5 axis machine tools. That is slick as glass. Some fine polishing can be done after the fact though.

Wolford

By the way articfriends, that post wasn't directed at you. Just adding to it more or less.

Waid

articfriends

iTrader: (1)

Oh no problem, we couldn't ene find a set of new gears that were consistent enough to digitize, they seem to have alot of inconsistencies. I would like to know the truth on the stock merc gears though, some guys claim they are made in China, sanother claim (that I believe) is the same forging dies have been used so long that they start to lose their consistency.
Rm builder talked to a gear vendor company at PRI or SEMA that had built sets of gear for a drive rebuilding company,they failed during testing and they never picked up the last few sets although nothing I would invest in as it was a guaranteed failure.
The problem every person in the know told me again and again was even though there are all kinds of kick ass alloys out there it would be hard to get the root strength in a "cut" gear vs a forged then machined gear, not saying it can't be done though, Couldn't a gear be digitized then "touched up" electronically to average out aspirations and abnormallitys?

waconda

It seems a lot of us have went down the same path on the gear sets in the last few years, that is how and why we developed the Bravo Shop gear lube.
For the size of the gears in a bravo drive there are not a lot of options to improve the strength of them, so the next thing was the gear lube and with the technology of today and additives available we were able to build a very successful Gear lube that has proven it self in all kinds of outdrives to be the best oil on the market.
Along with the special Cryo treatment and heat treat that we had help with from Dr Barron we have been able to improve the life of all types of drive gears.
While this is only scratching the surface of this very talked about issue it seems to be what most believe to be the root cause of the failures so we will leave it at that.

pstorti

iTrader: (2)

Just an idea but why don't you approach Mercury as a vendor to make the gears for them, someone is making them, if you were to make the gears for them in bulk you could experiment with different materials on your own. Maybe someone has already tried that.

ThisIsLivin

As I said earlier, I have access to a hand held laser scanner, if anyone is interested. The surfacing of the digitized data is a lot of work though. I don't really agree with the need for near net forgings though. When you look at high end connecting rods, many are made from billet, even cranks are made from billet.

PatriYacht

There are cad programs for gears. Plug in a few dimensions and the program will build a cad model for you. Nobody wants to do it for free though. Then, how do you machine the clutch side after heat treating?