# stump jumper stripped splines



## willy j

I have an old Bush Hog 276 rotary cutter. Took the stump jumper off to look at the output shaft from the gearbox and the splined receiver on the stump jumper because of some play in the stump jumper when I grab a blade and move the stump jumper up and down. No play in the gearbox drive shaft. Mower's been workin fine but I've had my eye on this issue for a while and over the years have repeatedly tightened the bolt that holds the stump jumper on.

The tapered splines of the gearbox output drive shaft are in reasonable shape but the splines of the stump jumper are chewed up except for the last 1/2" where the splines are deepest. Bush Hog replacement parts for the stump jumper and gearbox output drive shaft are ~$400 each. I paid $500 for the cutter more than 10 years ago.

What do you recommend? The pics I got didn't come out good. I'll try to get some better ones and post them.


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## willy j

here are pics


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## Fedup

Your photos are more than adequate to show the condition of what you have to work with. 

Unless you're terribly fond of that machine, I'd say you call it good that you got ten years use out of it, and look for another machine. Unless you find used parts, I somehow doubt you can get a shaft and a new hub accurately welded onto the blade holder for $400. Then add the work of installing said shaft? I do a lot of mower/batwing gearboxes and I know it's never as simple as it seems. If you replace the shaft you won't want to use the same bearings. You will need seals, probably some shims to set the gear pattern and backlash, it all takes time. You will no doubt have more questions than answers. If you really feel the need for the experience, then by all means go for it. 

You want opinions? That's mine.


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## LouNY

If it where mine and I didn't want to replace the whole unit.
I would turn the mower upside down put the stump jumper on and torque the heck out of it then remove the nut and weld the stump jumper to the shaft, if it loosens while removing the nut rig up a yoke or something to apply considerable pressure to the stump jumper then weld it.
Is it a nice proper fix, heck no. Will it get you several more years of service out of an old mower most likely.


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## willy j

Thanks Fedup and Lou. I'd like more opinions. Lots of you guys have dealt with this. What did you do? Machinists, wanna weight in? Can I bore that splined receiver out or is it hardened steel? I'm guessin the drive shaft is but not sure about the receiver. And what stuff did you do that you wish you didn't? Any flyin saucer stories from failed repairs?


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## Ultradog

I'm with Lou.
You aren't going to fix that cheaply.
Weld it on and start looking for a replacement.
It might give you a year or two of service or it might fail early where the welding has hardened the shaft.
I can tell you a flying saucer story.
Had a BH 305 behind my Ford 3000 tractor.
Was trying to clean up the weeds/brush along the small river that borders my property.
So I would back up to the bank - back and forth, 5' swath at a time. All of a sudden the whole thing went quiet. PTO was still turning but mower not cutting. I shut down, looked underneath and I had lost the entire stump jumper.
I put shorts on and went wading. Water is about waist deep. Found the part about 25' feet out in the river and half dragged, half rolled it back to the bank. The nut holding it onto the shaft had come off. Ordered a new nut and washer from BH dealer and next week finished the mowing.
Used Locktite the nut on this time.
I have since sold the 305 and bought a 306.
Great mowers.


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## BigT

I found that there are inexpensive weld-in hubs, maybe you can find one that is compatible with your Bush Hog. Ebay has a selection, click on link below.

https://www.ebay.com/sch/i.html?_fr...t=0&_odkw=ROTARY+CUTTER+BLADE+HUB,+15+SPLINE+


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## willy j

Thanks for the replies. Especially enjoyed the "took my stump jumper swimmin" story. I'm impressed you found that thing 25' away in the river and then dragged it out. I'd much rather that thing fly off in the water than when I'm on uneven rocky ground! Glad no one got hurt.

I've been waiting to get a splined hub, like BigT brought up. Have any of you done this? The major issue for me is boring out the old splines. I'm waiting to get the hub and put it onto the drive shaft to make sure it's gonna fit ok. While waiting for that part I took the gearbox apart to make sure the hub insert is worth doin. I was happy to find the gearbox clean, no collection of metal chips, gears ok, bearings ok, no signs of abnormal wear. If the hub insert fits ok I'll cut the stumpjumper crossbar off the pan so I can machine the stripped splines out. Then weld in the new hub and put some new seals in.

Some random gearbox pics. BH 276
input drive shaft and front cover








Casing with output drive shaft in place. upside down.








Output drive shaft.


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## LouNY

That will be a good repair.


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## willy j

Hope so, but it ain't done yet. I've thought about how to keep it from immediately flyin off if the welds on the insert hub fail. I'll keep postin as I go through the repair. If it's like everything else I do, it won't be a straight line.


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## James Jackson

willy j said:


> I have an old Bush Hog 276 rotary cutter. Took the stump jumper off to look at the output shaft from the gearbox and the splined receiver on the stump jumper because of some play in the stump jumper when I grab a blade and move the stump jumper up and down. No play in the gearbox drive shaft. Mower's been workin fine but I've had my eye on this issue for a while and over the years have repeatedly tightened the bolt that holds the stump jumper on.
> 
> The tapered splines of the gearbox output drive shaft are in reasonable shape but the splines of the stump jumper are chewed up except for the last 1/2" where the splines are deepest. Bush Hog replacement parts for the stump jumper and gearbox output drive shaft are ~$400 each. I paid $500 for the cutter more than 10 years ago.
> 
> What do you recommend? The pics I got didn't come out good. I'll try to get some better ones and post them.


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## James Jackson

If you have enough of the female spline to be able to do so, go around the outside and drill & tap 1/4" holes and put set screws in so you can tighten them after tightening the retaining nut (bolt) very tightly. You can also drill through the collar & shaft and put a roll pin through it. I would use red lock tight on all the fasteners.


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## ck3510hb

Have you checked the parts yard? I had a gearbox on a woods mower break, could not get replacement and the dealer gave small trade in to use it for parts. Just a thought.


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## BigT

willie j,
Couple of things that I would typically be concerned about if it was my project:

1) Getting the hub mounted perfectly centered in the stump jumper assy. A small eccentricity will cause vibration, lead to cracks in the deck, early failure of the gearbox, etc. I would rely on a machine shop to do this precision work. 

2) The splines on the gearbox shaft show some wear that will likely cause problems down the road. I would use epoxy on the shaft splines and the hub splines when final assembling to fill voids and prevent movement. But, if you ever want to separate the hub and shaft thereafter, you will have to heat with a torch to break down the epoxy.


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## willy j

BigT, I agree with your comments about the importance of alignment of the hub insert. I'm gonna do my best. When I took this project to a machinist he estimated 4 hrs @ $80/hr. I had brought him the stump jumper and asked him what he recommended to fix it. Could he do it? The problem of course is the size of that pan, over 30". When he said he had the equipment to bore out the hole, I asked him about using an insert hub. I told him all he had to do was bore out the stripped splines to a diameter that would accommodate the hub, get it alligned properly, and I'd weld it. When he told me his 4 hr estimate I figured either he didn't know what he was doin or he had better things to do than mess with this little project.

After tryin the machinist, I decided to do it myself by cutting the pan off the metal bar that contains the splined receiver. That lets me use a friend's mill and lathe to do the work. 

I also agree with your concerns about the splines on the gearbox output drive shaft. It's not uncommon for a shaft to have developed a shoulder under these circumstances. So when you put a new splined receiver on the shaft, it either won't suck up onto the shaft all the way, or it may look like you've got good engagement when you look at the end of the shaft and the stumpjumper, but there's some side to side play further up the shaft that may not be apparent until a while after you've done your repair. I want to be able to assess that issue by putting the insert hub on the shaft. That's part of the reason I took the gearbox apart, so I can get a good look at how the insert hub fits onto the shaft. (The other reason was to make sure I didn't fix the stripped spline problem on a cutter whose gearbox was all chewed up inside and waste my time.)

Regarding epoxy, I'll mention that a product is available that says it will accomplish a similar repair with the added hope of being able to separate the shaft and receiver. It's called Metalink by AMS. It aint cheap but if it works it might be worthwhile to someone. Don't know. Never used it. Here's the link https://appliedmaintenance.com/spline-shaft-repair.html.
Personally I regard sleeve bushings, epoxy, lead filling, and other measures designed to take the slop out of a drive chain as inadequate in an application like this that involves so much weight and speed and abuse by bouncin off rocks and other crap. But I have been surprised at the strength of some of these new expoxy-like compounds and am always ready to find a quicker, cheaper, simpler way to do things.


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## willy j

Here's some pics.
Cut the drive shaft receiver off the stumpjumper pan so I can mill it.








Remove chewed up splines from receiver. Mill with boring head.








Bore out receiver for new splined insert hub.


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## Tx Jim

IMHO the nut on gearbox output shaft was not properly tightened to enable either one of the ""tapered splined"" components to fail.


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## willy j

More pics. Hub insert plans, turning, and insert before welding.


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## LouNY

Looking good so far,
I'd be tempted to bevel the upper end so as both ends could be welded.


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## willy j

Thanks Lou.
You may not be able to tell from the pics but both ends of the insert and bore are beveled for welding. Definitely welding both ends. Only question is how many passes.


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## Tx Jim

Repair looks excellent at this stage.


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## willy j

Welding done.















Gearbox going back together. New seals.















New input shaft bearing.


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## willy j

Here's the stump jumper welded back together. I initially tack welded the stump jumper bar to the pan at either end of the bar. I then put the stumpjumper back on the bush hog with the gearbox reinstalled. I checked alignment relative to the bush hog deck, made a small 1 or 2 degree adjustment, and then completed the tack welding. I removed the stumpjumper and welded the bar to the pan. When I get the bush hog completely reassembled and running, I'll give a followup report. Will it run like a train goin off the tracks or will it behave? I've done a rough check on the balance of the stumpjumper without blades by positioning the stumpjumper on its visual midline on a steel rod on the floor. That's only a pretty rough check.


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## willy j

Here's my closeout post for this project. Finally got it all put back together. Very happy with the result. Time will be the final test and I'll report back if there are problems.
Here's a list of project materials and costs.
tapered 15 spline hub insert $30
milling boring head set with 9 carbide boring bars $120
gear oil $8
bearing $15
two seals $18
nut/cotter pin/washers for gearbox output drive shaft $40
gasket material $7
welding rods, paint already had on hand
total cost $238

Thanks for all the help and advice!


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## willy j

Followup. Its been a couple months now and I've had a chance to see if this repair holds up. This has been a stout repair. I've bounced the stumpjumper off rock outcroppings a couple times now and its holding together fine. Haven't had to retighten the driveshaft nut that holds the stumpjumper on or make any adjustments after putting the repair together.


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## willy j

Final followup unless the repair fails or there's a problem with it.

The slop is gone between the stump jumper and the drive shaft. Haven't had to re tighten the drive shaft nut or make any adjustments since doing the repair. This has been a good repair unless proved otherwise in the future and I'll post it if there are any problems. I would recommend the hub insert repair for stripped splines on a stump jumper to anyone with the equipment and time who wants to save a few hundred bucks and not have to buy a new cutter or stump jumper.


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## deerhide

willy j said:


> Final followup unless the repair fails or there's a problem with it.
> 
> The slop is gone between the stump jumper and the drive shaft. Haven't had to re tighten the drive shaft nut or make any adjustments since doing the repair. This has been a good repair unless proved otherwise in the future and I'll post it if there are any problems. I would recommend the hub insert repair for stripped splines on a stump jumper to anyone with the equipment and time who wants to save a few hundred bucks and not have to buy a new cutter or stump jumper.


Next step: clean it up, paint it yellow(or whatever paint you have on hand) put it on your trailer and go to the nearest dealer and trade it in on a NEW ONE !


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## Jcksnghst

Thank you for this, I'm facing the same repair on a BH3210.


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## lannislittle

IF you are reading this because you have similar problems..... I was headed down this same route but ran out of time. I have an old stumper jumper off of a 6' BUSH HOG 286 and the new spline that needs welded in. I also have a brand new oval shaped stump jumper for a 6' BUSH HOG Squealer. If you think either one of these might help you out, im willing to sell either (or both)


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## macdoesit

Rebuild or new, use Molly on the splines.


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## lannislittle

macdoesit said:


> Rebuild or new, use Molly on the splines.


I hate to ask now that it’s all back together…. But why?🤷🏻‍♂️🤦🏻‍♂️


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