Have just opened the upper unit on a Bravo 3 XR with about 300 hours. All the gear teeth have a linear mark where the gear teeth make contact with each other. There is no pittting nor pores. My boat is a 40 ft formula with twin 500hp efi's. Boat weighs about 19000 lbs. The outdrive oil gets changed every 50 hours and both drives have showers. The boat is a family cruiser and is not driven hard.
My question: Is it necessary to replace the gear set?
Thanks for any info

You must be living right

I've never had a set last that long.

Check for cracks between the teeth.


When they start to decompose the
magnets on the drain plug start to show it.


My experiences are with them is that you either get a good
set or a bad set.

You could end up spending $ 1600 for a new gearset
and they take a dump in 10 hours.

Thanks Jaay Teee, Will take your advise and keep an eye on the magnets for any metal. If I see any will then change out gearset.

right now you have a potential $1,500 gear set to replace (x2).......if you wait until they break you could very likely have a $4,500 upper to replace (x2). You may consider rotating the gears and use the back sides. Some say you'll get more life out of them...others believe it will stress the gears in the other direction causing them to fail quicker. (it's your call)

I have sucessfully flipped forward and reverse gears several times. But, it wont help a worn pinion. The pinion will always spin in the same direction. If your gears have wear marks forming, that means they are starting to fail. Replacing them may sound like the best option. But, with the low quality of gears Mercury has had the nerve to market these last few years, you may not get your moneys worth. Although this next option still requires the use of Merc's potentially weak gears, you can just install new pinions and flip the forward and reverse gears. That way, you will at least have new smooth surfaces on the load side, in forward and reverse. Any way you ckoose to go is a crap shoot. The one thing that is for certain, your next set of gears wont last 400 hours.

Is mercury the only supplier of these gears? Any better companies? If not the flipping sounds like a good option. The other sides are pristine. At the present time money is a serious concideration. Let's see, a new set of gears or the childrens tuition!?!

I was telling one of my shop guys about how much the gears cost and he told me NO WAY....someone can make them for less than that. So I brought an old set in for him to look over. After a few seconds he handed them back.....no way he could make them any better or any cheaper. I told him he could sell them $750 a set as fast as he could make them......he didn't even seem interested anymore.

I second Vinny's suggestion.. replace the pinion gears and flip the driven gears. With lines started it is may only be a few hours before they start to pit. And you may not catch the particles unless you pull the plugs after every run, and still may miss it. Once a tooth starts to come apart, it will fracture, the next tooth will try to go a few rpm's later, then the pinion walks over one of the teeth and spits the pinion out of the front of the case, ruining the case.

There have been several people attempt to make new gears, not an easy process. I was quote $250K per gear for the first ones. If you want to solve the problem and not send your kids to college, then go to the SCX.. Sorry, but Merc is the one selling the inferior product.
PS.. I have over 300hrs on my XR gears in my B1 with 700hp in front of it, in a 5700lb boat. And as Vinny says, next set wont last near that long.

Hope that helps
Dick

I want to thank all of you for the great advise. I'm going to flip gears and get a new pinion. I'll let you know how it goes!

Ofcourse you do, you trained me how to rebuild drives.