Another MX6 Brush Hog Failure

[deere5105]

Picked up cutter this morning. Got to mow with it this afternoon for couple hours. So far so good. The gentleman helping work on it was a little concerned with the fit and tolerances on the gears, but seems to be running ok.

Wound up finding output shaft gear and input gear for around $500 on eBay, had to order shim kit from JD for around $100 as gears were binding without them and paid gentleman helping $200 for his efforts. $800 an back working. If had it to do over, probably would purchase a new gearbox and just replace old one. Repair guy does a lot of work replacing decking and gearboxes on cutters and brought up good point could have had a new box with new gears, bearings, seals, etc... for what I spent on the gears. If this set runs another 14 years I will be satisfied and will just replace the gear box.

 

[JimR]

Picked up cutter this morning. Got to mow with it this afternoon for couple hours. So far so good. The gentleman helping work on it was a little concerned with the fit and tolerances on the gears, but seems to be running ok.

Wound up finding output shaft gear and input gear for around $500 on eBay, had to order shim kit from JD for around $100 as gears were binding without them and paid gentleman helping $200 for his efforts. $800 an back working. If had it to do over, probably would purchase a new gearbox and just replace old one. Repair guy does a lot of work replacing decking and gearboxes on cutters and brought up good point could have had a new box with new gears, bearings, seals, etc... for what I spent on the gears. If this set runs another 14 years I will be satisfied and will just replace the gear box.

A John Deere gearbox will cost you more than double of what you spent. Plus you will need a new stump jumper. They sure got this deal rigged but good.

 

[deere5105]

A John Deere gearbox will cost you more than double of what you spent. Plus you will need a new stump jumper. They sure got this deal rigged but good.

Might would have painted a new gearbox green to match.....but would not have been a JD gear box. Repair guy is somewhat of a machinist too. He didn’t think would be any problem making stump jumper work back.

 

[JimR]

Might would have painted a new gearbox green to match.....but would not have been a JD gear box. Repair guy is somewhat of a machinist too. He didn稚 think would be any problem making stump jumper work back.

I would consider the same if I break another shaft on my MX6. There has got to be a better and cheaper way of fixing these without using John Deere gearboxes. I think JD needs to come clean on these failures.

 

[deere5105]

Put about 3-4 hours in this afternoon mowing Bahia field. Hearing some noise when first engaging PTO. Engage slowly around 1000 RPM and then increase RPM. Heard same noise when in thick grass. First thoughts slip clutch needed adjusting. Sound was similar to it slipping. Made sure to slip it before starting. Tightened up on clutch bolts and it did improve, but didn’t go away. Not sure if is actually clutches slipping or the new gears making a racket. Other than the noise, no complaints so far.

 

[Zebrafive]

Put about 3-4 hours in this afternoon mowing Bahia field. Hearing some noise when first engaging PTO. Engage slowly around 1000 RPM and then increase RPM. Heard same noise when in thick grass. First thoughts slip clutch needed adjusting. Sound was similar to it slipping. Made sure to slip it before starting. Tightened up on clutch bolts and it did improve, but didn’t go away. Not sure if is actually clutches slipping or the new gears making a racket. Other than the noise, no complaints so far.

Use a paint marker to make a line across the slip clutch discs and later see if they are still in one line.

 

[deere5105]

Use a paint marker to make a line across the slip clutch discs and later see if they are still in one line.

Tightened up on the clutch bolts, marked the discs and heard the noise for just a second. Checked and could see where clutch had slipped. Apparently I had backed off or the guy working on the mower had backed off the bolts quite a bit. In the past I had it set and just backed off a round or two to slip the clutch and then tightened the same number of rounds back and moved on. Puts me a little more at ease that the noise was only the clutch. No signs of seals leaking and seems like cuts like it always has. Glad to have this behind me.

 

[bh3zfc]

So you guys really haven't found a box that will just mount back up on the JDMX6 cutter? I have the same issue, cutter has less than 100 hours easily. I priced JD and that's not going to happen and I found the same gearboxes at the Green Part Store for the exact gear box for 891.00 and a new version of that gear box for 891.00. My issue is I dont want to put this kind of money in something that I don't even know if the casting problem was fixed. I did find the shaft kit on ebay and that vendor told me he had sold over 1000 of these kits to fix the MX models. JD has not responded to me at all on this matter but you would think they would want to at least admit there is a problem. I will most likely buy a USED bush hog that looks like it want last because those usually last forever.

 

[bumperm]

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So you guys really haven't found a box that will just mount back up on the JDMX6 cutter? I have the same issue, cutter has less than 100 hours easily. I priced JD and that's not going to happen and I found the same gearboxes at the Green Part Store for the exact gear box for 891.00 and a new version of that gear box for 891.00. My issue is I dont want to put this kind of money in something that I don't even know if the casting problem was fixed. I did find the shaft kit on ebay and that vendor told me he had sold over 1000 of these kits to fix the MX models. JD has not responded to me at all on this matter but you would think they would want to at least admit there is a problem. I will most likely buy a USED bush hog that looks like it want last because those usually last forever.

If you have welding capability, or a shop nearby, one can mount almost any gear box on any mower, just drill and plasma (or torch) cut hole for new box on a 3/16 or 1/4 sheet of steel and weld that to the old deck. Stronger than new with minimal fabrication.

 

[JWR]

If you have welding capability, or a shop nearby, one can mount almost any gear box on any mower, just drill and plasma (or torch) cut hole for new box on a 3/16 or 1/4 sheet of steel and weld that to the old deck. Stronger than new with minimal fabrication.

Yes, BUT lookout for mounting depth and assumption of shaft length down to the stump jumper. Doing as bumperm says you'll end up having to replace both the gearbox and the stump jumper unless very selective. The mounting bolt pattern distance down to the stump jumper must match and of course the gearbox output shaft and stump jumper have to mate well. (duh,... obviously.) In fact I supplied a used gearbox to a friend who mounted it on his old bushhog and tried exactly what you describe. The blade carrier would not clear the body of the bush hog. Had to start over.

BY THE WAY This being a very OLD thread, I just studied what I had said on it several years back & others comments. See post #129. This does NOT help/fix your dilemma and expense. I do think I have a better idea now of the reason for the widely reported MX6 problems. I am amazed that I see no other post in all that long sordid history that mentions this. (I could have missed it during review...)

I think that the MX6 problem was due to the design combined with users not rechecking tightness of the bolt holding on the stump jumper. The design is that one center bolt holds the whole thing on -- WITH NO KEEPER AND NO COTTER KEY AND NO CROWN NUT. That bolt is supposed to be torqued as i recall to 450ft-lbs. How many users will check that once in a while ? ALMOST NONE. Unless the user gets out his larger high rating air wrench he has no way to get 450 ft-lbs on that bolt. Those without such an air wrench will probably not find a long enough cheater bar. End result: The stump jumper and blades are going to fly off at some point (!) I used mine back in the 2001-2011 period and had around 300-400hrs on it. The stump jumper never flew off until I had used it for several years. Came off several times before I wised up, read the torque specs, and finally used a long enough cheater bar ! (And that is enough to break most 1/2" socket sets ...go find your 3/4". )

Bottom line: I am convinced that the bad rap on the MX6 was because:
-- the unsecured bolt that holds on the stump jumper came loose (eventually, just a matter of time) on a large number of machines
-- in some cases (like mine) I was lucky enough that it never broke the shaft
-- in many cases (reported on this thread and others) when the stump jumper came loose and went flying the weight of it hit the side of the hog body or something else and hit the output shaft with a huge shock of sideways force -- enough to crack or even break off the shaft.

That's how I think so many of them got broken. Pee poor design without any cotter key or way to prevent loosening of the center bolt. Unrealistic dependency on users to periodically check tightness, especially to a torque figure they cannot achieve with their socket set. That's my theory.