XR Gear Materials
 

Hi Guys,

Does anyone have the following information as far as what the XR gears are made of and how the are manufacturered?

· Alloy of gear

· Forming operation (i.e. cold hot or forged)

· Method of hardening (i.e. induction or case hardened)

Thanks for your help.

Mark

Sh!tty
P!ss poor
Not very

Hope that helps.
PM "Smitty" he has that info I think.

What are you up to now, Mark?

Yes, why?

stuff :cartman:

I had an upper gear set fail after ten hours of use (All work was perfromed by certified Merc Racing Tech who has worked on my stuff before with zero issues.) and where the gear broke it was obvious the casting was bad. Straight line crack all black on one side and bright silver on the other.

I have a friend who is a metalurgist looking at the failure and he asked for the information.

The term "near net forged" comes to mind.

I have a rather nice collection of these.

This collection includes a specimen of each type
of failure that's commonly known to man.

I don't know what you're up to, but you're more than welcome to borrow a sample;)

if the x and xz gears are the material any ideas why they seem less susceptible to this type of failure?

The XR has only one tooth in contact at any giving moment where as the x and xz have 2 1/2 teeth in contact.

1st - It is possible to get bad gear sets, send it in to Merc and get it warrantied if it only has 10 hrs on it.

2nd - Most of the time if the housing has had a gear set go bad it is most likely stretched and pinion bore is out of position, or the towers are bent. Very few people even think about this let alone have the tools to check the housing and towers after a failure.

3rd - Think about most people you know that have had a drive blow a gear set and have it rebuilt and just like you have it blow again in a short time, all because there is more to rebuilding a drive than putting in a new gear set. We junk a lot of housings do to stretch. XR housings seem to be worse off do to the size of the broken teeth that are going through the pinion and driven gears. Most of the time it has enough pressure to break the top cap bolts.

Off the top of my head I don't remember what the alloy is that is used. Like Waconda stated, if you had a failure at 10 hrs and it was installed by a certified registered tech, you have a good case for a warranty claim.

The issue with any XR gears is that there is a stress riser at the back of each tooth where it is closest to the center hub. If exceeding stock horsepower, the clock is ticking away that it will fail.

I am in the process of making a better mouse trap. Un fortunately my progress is slow right now.

The pic shows what I am talking about.

Smitty

for how long they last i think they are using pot metal!!

Already tried Merc and they decided it was "Driver Abuse" that is why I am having it checked out independently. I have stock power within the HP range of the drives they don't want to back the gearset and with the number if these I have on the shelf I can't afford to drive the boat hard. This particular gear broke at the center cirle noted on your picture straight through the gear.

I'm sure all of us that have broken gears, cracked off the tooth at the same spot.

I am in the car repair business. Call the customer service line for Merc. Ask nicely first and then keep asking and asking and asking....the squeaky wheel gets the grease if you know what I mean.

Are you looking for total compensation or just for the gearset ??

Merc denied a merc dealer warranty? Or did you try and get warranty yourself?

With all the CNC technology available has anyone tried making some billet gears yet? There are some new ultra high strength steels like EN26. Heck I used to work in a die shop and used a piece of 6250 to make a sledge hammer over 30 years ago. I have beat the daylights out of all sorts of things and that piece of steel barely has any marks on it. For what everyone has spent on rebuilding drives it seems reasonable to consider making a set of $5000 gears to be done with the problem. I am going to hunt down a guy that's an Engineer for American axle and see if he can help with the material selection and manufacturing. Let me know what everyone would be willing to pay for some serious gears and what style would be the preferred type, I'm thinking XZ?

Thisislivin..

Already working on doing that. So far I have not found a gear guy who can match the tooth profile by cutting the gear. And a harder material is not the fix. You want the material to have a slight give and return otherwise the in and out of the water will break the teeth for sure. Removing the stress riser is the goal. The gear is also made of two pieces and fusion welded together. Stay tuned...............

Be interesting to see what your gear guy says......

I've looked into having gears made also. The problem is, it's a complex gear with the cone. The gear could be cnc profiled and heat treated but then it would have to be re-machined to put the bearing surface in the cone.

The present material seems to be something very soft like 1020 for easy near net forging and then it is carburized. The base material is too soft to support the thin hard layer so it just flakes off eventually. I would like to try S7 tool steel as it has good shock resistance and deep hardening properties. Enough steel to do 3 gears is about 200.00. The real cost is in the machining.

Dealer

I had Padnos shoot a sliced gear with their magic gun.. this is what they told me..
Zn 1.7%
Ni 3.0%
Cu 7.3%
Fe 86.7%
Mn .5%
Cr .14%
Ti .11%

Not sure if that is consistent, they only took one shot at it.. and can't remember what they said it was close to..

The clock is ticking if you have a mercury drive period! My boat has blown two up in 185 hours with stock horsepower. Horsepower has almost nothing to do with it... its torque.

Gaz-

Absolutely correct. As I stated, the stock gear has a weak point. I have 100 hrs on XR's with 850 ft lbs peak torque and have made them live this far by being nice to them and not airing it out. If you are breaking gears with stock power, you may want to alter your driving habits ???

Go back to my first post and look closely at the pic. I will eliminate the gear weak spot. Then of course that will expose the next weak link.

IMHO If you can't hole shot your boat with a STOCK Mercury drive/engine combo. That POS drive does not belong on the boat!

Other than that I don't know what could be considered bad driving habits.....It's not like the boat has been anywhere near jumping out of the water and re entering under power.

If you want the rush of a holeshot, buy a true ski boat or jet ski. Doing a holeshot from rest is clearly the reason why you are breaking drives. It is OK to go full throttle once the boat is ON TOP OF the water.

I'm no expert but I would think that during a hole shot in any outdrive equiped boat, that over time some component will eventually fatique, Not the Crankshaft, but anything other parts are fair game, Couplers, u-joints, drive internals, prop blades, add in a heavy boat with a single drive, something will fail sooner than later. once again I'm not a mechanic! but!!!

smitty,it also appears to me that the cases can flex a lot when power is applied[holeshot],this can cause gear contact area to change,making the problem worse,what are your thaughts on this?