Understood.

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)

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...

Thanks....