Last weekend powker run i broke the collor off the tube that holds the drive shaft in the drive only the very end with the threads in it .took my drive to shop found two others the same problem the same poker run and same drive . Also the shop had 10 other boats in with many other problems much worse than mine from that run.
Any input would be appreciated.
Rich

When Merc came out with the XR drive the area where the retainer nut screws in is thinner, because of the design of the retainer nut itself. That is what holds the pinion bearings and input shaft in place. When a tooth lets go on the XR gears the pinion will attempt to walk over the next tooth and then pushes the pinion out of the case, causing the weak point (thinner area) to break off. Just like in your situation. Did you have missing teeth on your driven gear?
If so that would be the cause of the case breaking. No good way around it, except to replace the case and upper gear set and proper set and hopefully a good set of gears from Merc. In my opinion, Merc's quality has slipped and they are selling gears that dont hold up.. but just my .02.. Good luck with it.

Hope this helps.
Dick

Thank you Dick
My gears are in good condition my spline is slightly twisted as to lead me to think I got air and didn't pull back on throtel but I was sure that wasent the case but the shaft got twisted and I think I am responsable.
Rich

Bad news today i thought the input shaft broke the collar of the case with no damage to gears my mistake one tooth out just don,t understand very minimal were i mean only a trace on all teeth why only one when the gear on each side take the incoming load and the out going evenly , mercury repair center can not explain why any input.
Richard Cuny

Sorry to hear your troubles, but wow. Good call Dick.

I've heard the same thing about Merc's stuff. When I replaced both my drives last season, I only got10more hours on them before layup. I pulled them off and had my marina mech. got thtough them to check clearances. 1 was just slightly off,the other took a lot of work to get it withing tollerances. My mech. epected a little but not as bad as they were.

I have seen and heard about this happening a lot lately. One tooth broken off the driven gear. My explanation is that Merc's quality control is slipping. I have heard they have switched suppliers over the years. When the XR's first came out, the lash was consistent around the gear. The first problem I noticed was soft pinion gears. Some think it was setup. But I had a pinion gear that was done in 40hrs. Changed it, without changing setup.. 270hrs later still good. That tells me the first pinion gear was soft.
Next I see gears with a wide variation in lash around the gear. Merc's tolerance is, set them up at .012"-.015" and I see as much as .012" variation in some.
Now there are a lot of gears breaking teeth off with minimal hours and slight signs of wear.
My .02", Merc is not paying their quality control guys enough to through out the bad product. Or make sure the gears they are building are quality product.
They built a better mouse trap.. the NXT. So now should they keep the XR's quality up so we can over power them and get some sort of usable life out of them?? Maybe they want us to all buy new boats with NXT's, seeing that it is next to impossible to buy an NXT drive setup to retrofit your boat.
If things continue the way they are going with Merc XR parts. I will start promoting the IMCO SCX as opposed to trying to build an XR that will hold any power. Problem is the guys running stock power will find the weak components as well as people trying to run more power. End result we all loose!! And Merc sells more parts.
Just my view on the subject from a repair stand point..

Dick

What size boat is this drive on?
Single or twin?
What size/ capacity motor?
What horsepower?
What is max RPM?
Drive oil brand and viscosity?

ALL the XR's I have done have had a variance of backlash on the drive shaft housing pinion.
My own boat and my customers are getting better durability now with X drive shaft housing gears.

Steve

I heard that the NXT uses the XR gears in its tranny, if that is thru then what the hell is the diffrents ?
Not that i have either ,but just wanna know .

Any news on that ?

Steve,
How much variance in lash are you seeing on the upper XR gears?

The NXT uses the gears for reverse, other wise it is straight through in FWD. Think of an XR on it's side with the input shaft entering the top of the drive and output the bottom of the drive. When in FWD the input shaft is connect directly to the output shaft by the cone locking into the bottom gear. When in Rev the pinion gear is used to transfer motion from the top gear to the bottom gear, used as an idler gear, causing the output shaft to rotate in the opposite direction. I hope that makes sense??
LH and RH rotation is handled in the drive, by placing the driven gear in the top or bottom position.
If they had any weak points, I think we would have heard about it by now. Doesnt seem to be much negative press on the NXT to date..