Off subject you may already know but the stock oil line plumbing has three inverted flare connection points that restrict oil flow down to 3/8" dia. Taking those out really improved my oil pressure when running hot.

Too much power , 1.50 gear , 32 & 34 4blade's with -1 Imco lowers and building bigger power as we speak. Guess I should be buying some spare upper's.

I'm pushing over 1000 ft lbs of tq and hp, I can turn a 32 pitch 6000 so EVERYTHING is on borrowed time! I never had lower gear problems though until I started making over 700 hp and went from a 28 at the time to a 30 pitch, Smitty

Dick, I think there is a direct correlation between the older gears and power available "at that time" and the newer gears and "power that we are running through them now".

I don't believe that it's a supplier problem. I think as time has gone by, sales probably have fallen a little, a lot, and the average goat working at Merc is not spending much time on the setup.

I'm as guilty as anyone I suppose with respect to always trying to go faster. We want just one or two parts to bolt on and go faster. Due to budgets, we usually do NOT step back and look at the whole drive train and make ALL the upgrades that are probably necessary in a simultaneous fashion.

However, the natural texture so-to-speak regarding the little "orange peel" on the brand new gears tells me that there was work that could have been done that was not done in an effort to save money and the like...

More later.

Merry Xmas and Happy New Year!

Hi J, I've only seen this thread now. Sorry to hear of your XR troubles.
As you know, I've got the same stuff on my boat, though it only has to cope with the stock 496HO.
2006 vintage, 230 hours, and aside from changing oil I never even opened it to inspect - and neither did the previous owner, I suppose.
Time to have a look, according to what I'm reading... How complicated is it to open for inspection?

Oh, and all the best for your ASD project. Did you make any progress in the meantime?
I'm very curious to hear about the results, if you'll go for it.
Also re.maneuverability btw: our boats are not the most maneuverable around the dock with a single outdrive and high X-dim, I don't dare thinking how worse they could get with a surface drive....

i don't think this will help much for those with xr failures, so it is more of a personal experience story. i had 4 standard bravo upper failures on my single engine 950 hp cat. in 2005, i had imco upgrade one of the broken drives to xr with some of their other mods. this drive is still in the boats after 6 yrs with no failures or observed serious wear. part of this good result may be do to the earlier gears being stronger. i have a new RPM 26 which is nearly complete. even though it is only 800 hp N/A, i decided to go with the new imco scx-4 surface drive. i may have gotten by with an sc imco, but after reading about all of the failures with xr gears, i decided to play it safe. i only hope that the boat will be as fast and handle as well as with an sc or merc bravo.

i would replace those gears with X gears and when set up properly if it's a shimable upper, you'll get easily 250-300 hours on that boat. Call me if you have any questions.
954 237 0332 John

been reading this thread,and one thing clearly shows up:a lot of guys are pushing too much hp thru those drives...it is the marine equivalent of pushing 900hp thru a 10 bolt gm diff....you KNOW it is going to break eventually,because it was not designed for that application...im sure there are tons of xr performing their duty behind 496s,525s,even 600s with no issues...dont get me wrong...i still think merc sucks,but if i go from 600hp (presently) to 1000hp and my xr strips gears,i wont blame merc...
plus you're scaring the ch*t out of me,cause i just bought an xr!

The XR is rated at 600 or just above depending on which piece of lit you read or which person you ask.

It also comes as standard equipment behind the Merc blue 600 blower engine.. so I certainly don't feel as though I'm abusing it in any way.

Not to mention... I treated the XR much, much nicer than I treated the regular X drive. They made a change on those gears to save money. And I'm sure it saved money somewhere cause they are made way cheaper than the older ones.

If you consider the warranty replacements than I'd have to wonder if they really saved anything. Who knows?