nwimbush

Really?? I didn't know that was a possibility - what kinda $$ are we comparing? I lucked out and bought mine with two Bravo's, but they will need freshening before I feel comfortable with their reliability.

KAAMA

Either PM "Articfriends" or "Mr. Gadgets" and they will give you the scoop!

jeff1000man

I sure would like to know how he fits those oversize gears into that little bravo box. Every merc tech that I have ever talked to said that it has to be some drive in the "X" series to fit the XR gears into.

You sure you didn't have "X" drives when he got started.

Plese clarify, because that is an amazing and valuable technique that he has discovered.

I have 2 drives cluttering up the floor of my shop right now that I would gladly send over and have changed over so I could use them on other boats. I also have a couple friends. Probaly around 10 drives that we could send him.

KAAMA

Well Jeff, it's not written in stone, but right or wrong, not here to purposely steer you or anyone else in the wrong direction. Anyway, to answer your question, that is what I am quite sure both Articfriends and Mr. Gadgets told me, but hey, I've been wrong before and probably won't be the last time.

I also thought I mentioned to PM the men who do these drives...."Articfriends" and "Mr. Gadgets"....they are here on OSO much of the time---you can ask them for yourselves.

articfriends

Nothing revolutionary about it,max machine worx started doing this the minute the xr drive came out. A xr upper gear is phisically no bigger in diameter than a std upper gear,just slightly thicker which you make up with by shimming with thinner shims/different thrust bearings. The shafts are all the same length,the lower gears are identical with the same forging markings on them except the splines are broached 1/16" bigger in dia.
The strongest bravo is a std case bravo outfitted with xr parts with a upgraded tower. Max worx bores out the stock std bravo tower that is a failure point,installs a full length tower that is bullet proof then installs all xr upper parts or their upgraded version of them with the exception of the dia of the retaining nut holding the upper pinion gear in,it is bigger on a xr and is a failure point. The upper is stronger then because it will not blow the retainer out the front (see attached pic of broken xr drive). As far as the lower,you can easily substitute the xr parts into it,the housing is a identiacl casting,they even sell a upgrade kit that has a xr prop shaft,carrier and gears for this very reason.
I have been running a drive as I just described for over 7 seasons with various hp levels ranging from 650 to over a 1000 in my 27 foot baja. I have broken parts and found the failure point of certain components and I have also experimented with various ways of trying to get the xr lower gears to last longer. I have found that by cryo finishing the lower gears and sending them thru a multistep surface conditioning process that in my application I have been able to quadruple the life of the gears. Last season I took it a step further,teamed up with Bob Madera of Marine Kinetics and with his technical support and industry connections tested some state of the art coatings and further finishing processes. We are still waiting for lab results on test gears that were ran for set intervals and we are also in the process/planning stages of having some short runs of aftermarket gears made as we have found the base material used in mercruiser bravo gears leans more towards mass production and less towards higher hp levels,Smitty
the pic is of a broken xr casing,a std bravo casing is thicker at that point.

KAAMA

Just tryin' to help Jeff. Now that you have your answer, when are you "gladly" going to be sending out those 10-12 drives you were talkin' about???

jeff1000man

I'll send you my 2 for an experiment if it as cost effective as you say.

How much does it cost? t sounds like a pretty expensive and time consuming task. I was guessing that if it was as you said, that there was some extensive machining involved, because those parts don't fit in the stock hole.

jeff1000man

I was not trying to come off sarcastic in the first comment, it;s just that sarcsm is what we get down here from the suppliers when I ask the question about upgrading the regular bravo 1

Mr Gadgets

Jeff,
I am running a B1 with XR upgrade, that I had done years ago. I have about 300hrs on the drive at this point. I dont have big power, my 28' Check only runs 87.7mph best to date.
I install my own tower that is threaded 2" into the case. The drive can be built with your input shaft or a new one with Metric ujoints. Either way the gears fit with out machining. You could put XR gears in without the steel tower, but I wouldnt do it. I also use the XR ribbed top cap, because it has a steel tower in it. The cost of doing a B1 to XR upper does approach a point of dimished returns. The B1 case does have the thicker snout. But I have had one of the new style (hump back) with 1170hp and it was bumped up to 1400hp for a short period. It was only run about 15 hard passed before the end of the season. I tore it down and it looked very nice inside. The snout on the case isnt that much of an issue in my opinion. When the XR gears break a tooth, no matter what case it is in.. it can be fatal to the case, even if the snout doesnt come off. On the other hand I have seen an XR case with the thin snout survive when a tooth broke off and the boat was run 8miles back to the launch. Case was ok..
I dont like to use very old cases for upgrade to the steel tower. The rest of the case has weak points in it that I would rather see a newer case that has thicker bearing race seats.. etc. There are other wear points in the case that if worn.. will be rejected. You want the best if you are adding power, so no sense starting with a case that is worn too much!
If you like, pm me and I can work up a quote for you. And you can compare the differences.. Your email address, so I can email the estimate..

Hope this helps
Dick

jeff1000man

PM sent. Do you work with Artic friends? Bb madro highly recomends the guy. I talked t him earlier today.