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waconda 11-06-2012 06:48 PM


Originally Posted by MarkDonzi (Post 3810388)
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.

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.

Smitty 11-06-2012 10:00 PM

1 Attachment(s)
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

FIXX 11-07-2012 12:38 AM

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

MarkDonzi 11-07-2012 04:14 AM


Originally Posted by Smitty (Post 3810569)
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

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.

Smitty 11-07-2012 06:34 AM

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 ??

waconda 11-07-2012 07:06 AM


Originally Posted by MarkDonzi (Post 3810660)
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.

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

ThisIsLivin 11-07-2012 09:56 AM

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?

Smitty 11-07-2012 10:34 AM

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......

PatriYacht 11-07-2012 02:35 PM

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.

MarkDonzi 11-07-2012 06:58 PM


Originally Posted by waconda (Post 3810704)
Merc denied a merc dealer warranty? Or did you try and get warranty yourself?

Dealer


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