Well, after looking at your pic I'd say the mesh pattern in mine looks about like yours so maybe it isn't "that" deep..

Pretty unfortunate. Not available this week but I'm gonna start looking hard for the gears in other places.

Not holding my breath.

My hope is two fold:

1. That they can be found without Merc.

2. If they can, then hope that maybe Merc "told" the manufacturer to make them "cheaper" like the 525 cmi's and that perhaps a set off the shelf might just be better treated etc..

It is my thought that these low hr failures are due primarily to improper gear break-in. Mating surfaces of teeth are rough when new. High pressures on rough gear teeth during initial runn-in will cause loss of lube film and then galling of the teeth. A properly worn-in gear set will have smooth tooth contact areas and better lube film strength. This is prevelant in miter gears (XR) more so than spiral bevel gears (std bravo) because the tooth contact area is smaller on miter gears. Spiral gears have more of a sliding action and less "point loading".

BT

No wot for first 10 hours - vary speeds and throttle during that time. Then make some short passes wot in a few second bursts and change the oil often using one of the most expensive gear oils you can find....

What else can you do?

When you see a gear set flake out like that it has nothing to do with break-in. It's a simple fact that they are lacking the proper, time consuming and expensive heat treating.

You can rest assured Merc has them made as cheap as possible (kinda like those 525 cmi's that keep cracking often).

When you buy a brand new drive and pay the coin, going out and running the snot out of it is not the first thing on my agenda...

My thought is that it is probably not practical to break these gears in properly in this application. You'd need to run them at 1/2 load for several hours. Even getting on plane would ruin that process. They need to be "pre broke in" by micro polishing the gear faces or some other method. All in all I think the spiral cut gears are superior in application due primarily to what I mention. Maybe John the drive man will let us in on how he breaks in new gears.

If too much load during “Break-In” is a large part in shortening an XR gear sets life; it seems like going down 4” or more in prop pitch would help. Has anyone tired that?

That's a good idea. I was also thinking idling at a fast no wake speed for a couple hrs might do it. For the price of wrecked gears it may be worth it.

The lower gears in all Bravo's are straight cut
gears ( just like what XR uppers are) and they
dont require babysitting.

Lower gear failures are much more rare than uppers.

The B1 on my boat has XR upper gears in it.. Installed in 2001 or so.. I never really took extra care in breaking it in. I did the normal easy on plane, no WOT for a several hours. Since then I change my oil religiously every 40-50hrs, run it hard when I am on Lake Michigan. With my boat I cant really tell when the prop leaves the water. Had a fellow boater ask why I never let off when air born.. Told him I couldn't feel it. So I dont pamper it. The drive has 330hrs on it. I had to change out the upper pinion gear at 40hrs because it was soft and going away. I put a new one in and never changed the setup. Took it easy for a while, then back at it. No metal shavings on the magnets, last time I drained it.
But one thing that I am sure of, the lash variation on the XR gears and even the lower gears is all over the place. It used to be .002-.003".. Now it can be up to .010". Put a gear on an index table that shows if the teeth are all in the right place, tell me what you find.
When I started seen the lash change drastically, soon after the teeth started snapping off the upper driven gears. Used to be 250hrs was normal for 750hp in a light 6k lb boat. Now the pitting starts early on..
I think Merc needs to go back to their first supplier and hopefully all the old duffers that knew how to make them are still around.
Sorry about the rant, but just had to vent. If we could turn the clock back 5yrs, I would purchase a couple thousand sets of them.. and bring them back to the future.. Problem solved. :)

It's a complete f cking from Merc. They know these gears are junk. It's all about making money. Just as someone said about the headers. Suppliers can make gears hold up to tons of torque in diesel applications for industrial equipment.
But they can't make a gear hold up to 500HP in an outdrive?

Lower gears are in a different location in the drive train. Many additional variables would come in to play when comparing thier wear to upper gear wear; noise, shock loading, lub bath, heat and so on. My comment was concerning wear of different gear styles in the same position in a drive train. It is a fact that miter gears take much more babying on breakin than spiral cut gears, no matter what tpye of gearbox is being discussed. The lube film is key to preventing wear.

Understood.:drink:

I guess what I was trying to say is that Merc
calls the XR upper sets and all lower sets "near net forged"
(the same process)

In all actuality the lower gear sets are exposed to a higher
amount of torque ( since the upper gear reduction ahead of them)

Yes the lowers run fully submerged, the upper set
maybe half.

The lower gear sets dont have these problems for the most part ( just this year I had 2 different boats that had lower
gearset starting to chunk out, that I had to replace gearsets on, versus dealing with XR upper gearset issues for the
last 5 years)

I'm with Dick on this one...something changed about
5 years ago....and it wasnt just the price increases;)

My points are really aimed at trying to improve the experience people are having at present with the XR gears. They apparently are quite proud of them at mercury.

That said, I am sure you guys looking at these failures everyday and over the years know if something is amiss in current gear quality vs prior sets.

I heard recently from the owner of a top-notch merc shop
that the XR gears as they come from the factory are nowhere
near "ready for install" out of the box! he says every set he installs has quite a few hours of detailing (can't remember
exactly how many) on the gearsets before instalation, and that
different backlash and preload settings are involved. if you would like to talk to him, PM me and I'll give you his # for
his business (well known California based Marine shop):drink:

There was a lot of posting a while back regarding cryo treating the XR gears which alledgedly improved gear life/durability significantly. Micropolishing the gears was also involved at some point. Lower gear failure rather than upper gears was the focus. Does anyone know what is the latest is on that?

http://www.offshoreonly.com/forums/g...riment-21.html

SD,
Your post made me a bit nervous. I’ve a similar situation, but lighter boat and less hp. I wanted to see how my drive was holding up. In Feb 09, I purchased a new XR upper and have put 95 hours on it. The oil has been changed every 25 or 30 hours with Amsoil. My engine is somewhere around 560hp at 4500’ and close to 675 at 600’ (maybe 25 hours of run time at Mohave / Powell). This is what my pinion looks like. I’m not sure if it’s got lots of life left or about 10hr from self destruction. Either way, with all the talk of breaking cases, I plan to watch the oil color very closely.

What oil are you running?

If the rest of your gears all look like what you can see in that pic then you're fine for now.

Just start looking for them to flake out and leave pits and holes. There is no oil cooler on the drive so you should prob pull the top cap off every oil change and just turn the shaft making sure you can't see any damage.

Once they start pitting on the edges, it's a crap shoot. No way to tell how much time you have...

Sorry to monger the fear but it's better than waiting until it breaks I guess..

I use the AMS Oil as well - AGM

I take some comfort in seeing that your mesh pattern is basically same as mine without measuring it. I thought it looked real deep but as I said earlier... I've not had much experience with XR gears.

The clutch side gears show less wear, but I think it'll become an annual inspection for me.

Mr Gadgets, Has a neat way to cool the oil. I think its a great setup for when it has to be torn down...

I'm still interested in what oil your running?

Same as you... :party-smiley-004:

:eek:

Thanks....

Articfriends (Smitty) had dialed in a process to significantly improve the life of the XR gears in high HP/Torque motor applications back in 2007. He was also looking into a CNC gear set of a higher grade steel in 2008 and then everything went silent. When I blew my gears this spring I PM'd him asking about availability of a set of his improved XR gears and no response. MrGadgets was aware of his work per his posts on Articfriends thread on this subject. Does anyone know why this all went silent? Did Merc buy out his work to maintain the status quo?

Never happen. Ever. But hilarious none the less!!!

:drink:

As most find, it takes a huge stack of money to build a gear. Lots have looked into it, but few have proceeded past the check.. :(
I am doing the same cryo, polish treatment that Smitty uses. It seems senseless to do the upper gears as fast as they fail. But we have seen some improvements in the lower gears. The lower pinion gear is much softer than the driven gear. Seeing a failure at 7hrs use, the pinion gear was pitted and the driven gear looked like new (like they should).

I was not thinking that anyone could afford to develope a new drive gear especially for such a relatively small market. I was interested in the cryo treated gears.

I know from Smitty's thread that he was having accelerated lower Bravo drive gear wearout issues and not accelerated upper gear wear out issues.

I am not clear what you are saying. Are you saying that the upper XR gears wear out faster than the lower drive gears or the lower drive gears wear out faster than the upper XR drive gears?

Are you saying that Smitty and/or you tried the cryo/polish treatment on the upper XR gears and it provided no improvement in gear life?

No.. his upper gears are older than 5yrs, so are mine. We both froze and polished the uppers and it seemed to help, right up till the teeth start to break off a the root. Since then it seems pointless to band aid a bad gear. It takes a lot of work to get the bearings out and get them treated, just to have the gear fail and then some one says, well did the cryo hurt it?
So I have shyed away from doing the upper gears, actually I have been encouraging people to go with the SCX and not worry about the XR upper gears. Or go with the X gears and friends have had good luck with that.
I still thing the cryo is agood thing, just need a good gear to start with.. :(

Dick

Thanks Dick. I want to make sure that I understand what you are saying.

So you and Smitty tried the cyro and polish on the upper XR gears that were a vintage older than 5 years and it seemed to improve the gear life but instead of their normal wearing out they started to crack at the tooth root and had to be replaced for that reason. Is that correct?

Then you and / or Smitty also tried the cyro and polish on the upper XR gears of current vintage and there was no improvement in gear life versus upper XR gears of current vintage. Is that corrrect?

Or did you and / or Smitty not try the cyro and polish on the upper XR gears of current vintage because they are so bad to start with? Is that correct?

Mr Gadjets, the reason for all my questions about the cryo is to be fully informed and ready with the proper decision the next time my gears go south. My Bravo X1 is a 2004. It's history is as follows: 90hr @425hp, 26p B1 stock, and OEM lube, 80hrs@490hp, 40hr@ 540hp, 162hrs@625, for a 382hr lifetime total. Other than the first 90 hours all the rest was with a labbed B28 and Redline Shock Proof Heavy Gear Lube. Hull is 3700# and drive shower is from Nordic and is marginal (re upper drive oil temps reach 270F+ and still climbing during extended WOT runs). I have always been carefull to use only 50% throttle on plane out with the X1 gears. Most hours are cruising at 2500 rpm or wake boarding at the same with lots of starts and stops. Hard running is usually only for AFR testing one cylinder at a time when I change something. I knocked off two upper gear teeth this spring(lousy timing) while WOT testing a 26P5X and was not being quite as dilligent about the 50% throttle max on plane out. I had just changed the lube. The lower gears were found to be pitted as well. I have always found fine iron dust on the drive magnets at end of season lube change but nothing larger. Drive was rebuilt with XR gears so now I am in the same boat as you guys. I thought I was putting a better gear in for my power. After XR gear breakin done to the letter I checked the upper magnet and zero iron dust found but the lube seemed darker than normal especially for such low hours. Maybe from the lubes used in rebuild assembly.

I had 2 new XR upper gearsets cryo treated
about 3 years ago. ( and yes, getting the bearings out
of them is real fun)

One set started chunking out in less than a year,
the other set is still ok ( knock on wood)

What was your experience with non cryo'd XR gears?

Pitting, cracking, breaking teeth off...broken cases.
....all the normal stuff:rolleyes:

Do you think the cryo'd gears are lasting better?

After the one Cryo set crapped out, I put one of the old sets that I took out back in....ran it for 2 more years.

I had to replace one of those gears due to part of the edge of the brass ring was peeling off, late last year.

Otherwise it looked good ( no pitting)...it was an older set, that pre-dates the junk they're putting out now.

So, I cant tell if they're lasting any longer or not.

I experimented with various coating, heat treating and cryo processing of both upper and lower gears, I found that cryoing and polishing the gears along with running amsoil and lucas additive -on the advice of Max machine worx) seems to make them last 2-3 times longer under hard use (from pitting and galling) but does nothing to keep teeth from breaking and failing. I have 2 drives for my boat, both have old merc upper xr gears in them that have been run at over 1000 hp in my 2000 272 baja (a lite boat) and the uppers set up right have just lasted and lasted. Lowers however, were only lasting 10-15 hours before they were completely ate up, since settling on this cryo/polishing combination and the mentioned oil package last me 40-60 hours now though. I also tear my drive down and inspect it every 15-20 hours, I have found failing bearings, cracked upper shafts, sheared off billet prop shafts and vert shafts but again , i am running over 1000 hp and 1000 ft lbs of tq, Smitty
I still have the treatment applied to customers gears on a custom special order basis for customers on a custom basis

I wish Merc would have bought me out or funded my research :o:o but what really happened was I was trying to get lower gears to last and looked into having custom sets built with the assistance of RM Builder/Bob Madera, we sent sets out and had the mettalurgy tested, dimensions copied, etc with the intentions of having some built, we found one supplier that had already built experimental sets for Max worx that lasted less time than stocks ones and we were at the point of spending 10,000 plus dollars on a few test/trial sets of lower billet gears but my phone quit ringing with guys that even wanted stock ones treated let alone custom built ones and a short run after the experimental sets were going to be done was still going to be 50,000 plus dollars with no guarantee that they would even last as long as stocks ones! At that point, the need for upper gears seemed to be the biggest problem I was hearing about and everyone that has looked into having them built found it was going to cost well into the six figures again with no guarantee thery would last or even work. The gears are near net forged, the only way to have a gear with any real strength made would be to have forging dies and a capable company do it . cnc'd gears wouldn't have the root strength being "cut" not forged due to the grain structure unless some really exotic material was used and even then it still a 250,000$ flip of the coin, I have spent enough money already experimenting to get where I am at so I am having lowers and uppers cryoed and polished but again, I have 2 sets of the early "good" xr gears in my drives.
As far as aftermarket gears, I know for a fact there are aftermarket low qualit lower gears already out ther, the Chinese are using them in there 800$ lower bravo, there is no way they are buying 400$ lower gears to put in a 800$ drive, thing is, they don't offer them for sale and I don't think you would want Chinese gears anyways, Smitty
I was fortunate in this down turned economy to land a second job with a low six figure income, thing is I am still working 40 hours a week at my old job until I can retire and running my transmission/performance business with the help of my youngest son who I trained for 10 years so I am busy or gone 96 to 120 hours a week, doesn't leave much time for running/testing trial sets of gears anymore!!

Smitty, Thanks for taking the time with your busy schedule to give an update. Sounds like we need your work here more than ever given the low quality XR upper gears Merc is now selling.

What of all that you learned trying to improve the life of your lower gears with ~1000hp do you think could be applied to improve the life of a current set of low quality XR upper gears at ~600 - 700 hp where they are now prematurely failing?

You mentioned that when you tried re hardening your lower gears to provide a thicker/deeper hardened surface" After 17 hours they were chipped up exactly the same as the oem's,only difference was the little craters were much deeper because surface hardness was thicker." Do you think that that might improve the life of the current XR uppers for the lower torque levels of a 600 - 700 hp engine along with cryo treating as well? Same question plus the addition of nitriding?

I guess a better question would be what would you do to best improve the wear life of the current low quality XR gears for a 600 - 700 hp application?

Thanks for any suggestions.

Bill

How Bout Dis!
 

Hello Smitty:

Did you ever try QPQ nitriding on the gear sets to see if it helps the surface wear and pitting of the XR gear sets or lower gear sets. It won't obviously make the gears internally stronger but we've seen very good results on items we have QPQ Nitrided for surface strength and ductability as well as surface lubricity and increased metal strength .003" to .010" into the material.

Best Regards,
Ray @ Raylar

Geezus Ray now ya tell me!!!!!

:violent040:

No, we tried deepening the heat treatment and also tried DLC (diamond like coating) and because of the movement below the heat treated area the surface (or picture a egg like shell) still flexed and gave away, we had sets professionally analyzed with destructive testing and electron microscope exam, the final opinion was the substrate was allowing too much movement in the base metal under neath the hardening and nothing else could be done without new base metal. The cryo/iso treatment does seem to keep the surface from galling as easy but switching to amsoil severe gear did wonders too over all the other oils I tried, the royal purple I used was absolute GARBAGE, I wish I would have realized that sooner during my testing. I did try swepco and some others, did nothing , Smitty
As far as the new XR uppers, I hear that they crack and break with no rhyme or reason, the cryo iso will help keep them from galling but from everything I keep hearing they will probably break first, Smitty

Bill, it seemed like the heat treating just made the gear more brittle/ chips were deeper which could be expected when re-heat treating something already hardened, it was of no help, Smitty

Thanks.

In addition to using the Amsoil HD gear lube plus the Lucas oil additive and the cryo what would you do in addition to the current low quality XR gears to improve the wear life for a 600 - 700 hp application?

Bill