Bus Hog Model 306 Gearbox Repair Questions

[wjpferg]

Hello everyone! It's a pleasure to be a member of the TractorByNet family. This is my first post, and I hope that I am not asking questions that have already been answered in a previous thread that I missed.

I have a Bush Hog model 306 that has the #6163 gearbox, and the output shaft has been sheared off just between the stump jumper and the base of the gearbox housing. I bought it cheap along with a six foot harrow and a five foot box blade in hopes of replacing the shaft. The frame and deck of the bush hog are in great shape. It would just be a waste of a nice piece of equipment if I don’t try repairing it.

After opening the gearbox, I discovered that this particular model has a roll pin inserted between the threads of the upper shaft and the gear nut. I have tried to remove the roll pin with no success, and it is in an awkward position with minimal access. I emailed Bush Hog, and they told me that the nut had to be split or cut off because the roll pin has destroyed the threads in serving its purpose in locking on the gear nut. I have also examined the schematic, and it appears that the bearings for the shaft are installed in opposing directions that would appear to make it impossible to pull the shaft in either direction.



With this being said, do I just need to get out the cutting torch and start from scratch, or does someone have any experience with this type of repair?

 

[5030]

Buy a new gearbox. Lots easier and not expensive. Agri-Supply (ASC) sells them everyday.

 

[RickB]

Cut the nut off. Remove the gear from the shaft and the key from the shaft. Drive the shaft down through the upper bearing. Inspect the bearings and races, decide whether to re use or replace them. Order a shaft kit (includes upper nut and roll pin) and a lower seal, bearings if needed. Some 306 gearboxes use two seals back to back.

Have something real when you get done, not might fit Chinese crap.
Edit: I am not seeing a 90 hp gearbox at A/S with a tapered keyed output shaft.

 

[bullbreaker]

Wjpferg :welcome: to TBN ! ...........................:tractor:

 

[wjpferg]

Thank you! Pleasure to be a part of the group

 

[wjpferg]

Thanks for the information. I’m pretty sure I can do that. I have checked for optional gearboxes, and none that I have seen have a shaft that is long enough. I definitely want to fix this one.

 

[5030]

Cut the nut off. Remove the gear from the shaft and the key from the shaft. Drive the shaft down through the upper bearing. Inspect the bearings and races, decide whether to re use or replace them. Order a shaft kit (includes upper nut and roll pin) and a lower seal, bearings if needed. Some 306 gearboxes use two seals back to back.

Have something real when you get done, not might fit Chinese crap.
Edit: I am not seeing a 90 hp gearbox at A/S with a tapered keyed output shaft.

I never looked. My Landpride gearbox is peachy.

 

[BrokenTrack]

What RickB said...

I am in the midst of doing the same thing. I used an angle-grinder with a cut-off wheel to chop the castle nut off.

But he is also right in rebuilding these gear boxes. I have heard of some guys not even getting a single mowing done without breaking the Chinese tin gearboxes of newer mowers. I am not sure what year yours is, but my mower has got 55 years of hard use on it. I will gladly pay $80 for seals and bearings instead of $200 for a gearbox that will not last.

Oh, and welcome to TractorByNet: it is great to have another person here who rebuilds stuff, instead of is a parts-swapper. You are in good company here!

 

[wjpferg]

What RickB said...

I am in the midst of doing the same thing. I used an angle-grinder with a cut-off wheel to chop the castle nut off.

But he is also right in rebuilding these gear boxes. I have heard of some guys not even getting a single mowing done without breaking the Chinese tin gearboxes of newer mowers. I am not sure what year yours is, but my mower has got 55 years of hard use on it. I will gladly pay $80 for seals and bearings instead of $200 for a gearbox that will not last.

Oh, and welcome to TractorByNet: it is great to have another person here who rebuilds stuff, instead of is a parts-swapper. You are in good company here!

Thanks BrokenTrack, and everyone else, for the the the warm welcomes. I have to agree that a rebuild is the only way to go here. Even the best equipment breaks down, so just maintain it well and Repair it when it does. It will save you some cash in the long run too.

 

[Jeff Jones]

Hello everyone! It's a pleasure to be a member of the TractorByNet family. This is my first post, and I hope that I am not asking questions that have already been answered in a previous thread that I missed.

I have a Bush Hog model 306 that has the #6163 gearbox, and the output shaft has been sheared off just between the stump jumper and the base of the gearbox housing. I bought it cheap along with a six foot harrow and a five foot box blade in hopes of replacing the shaft. The frame and deck of the bush hog are in great shape. It would just be a waste of a nice piece of equipment if I don’t try repairing it.

After opening the gearbox, I discovered that this particular model has a roll pin inserted between the threads of the upper shaft and the gear nut. I have tried to remove the roll pin with no success, and it is in an awkward position with minimal access. I emailed Bush Hog, and they told me that the nut had to be split or cut off because the roll pin has destroyed the threads in serving its purpose in locking on the gear nut. I have also examined the schematic, and it appears that the bearings for the shaft are installed in opposing directions that would appear to make it impossible to pull the shaft in either direction.

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With this being said, do I just need to get out the cutting torch and start from scratch, or does someone have any experience with this type of repair?

I just did this to my Bush Hog 306, I had no problem just drilling out the pin and then using an impact wrench to remove the nut. The threads seem absolutely fine. When I reinstall I plan to re drill the hole and put a new pin in. My shaft broke just below the gearbox but unfortunately the lower lip of the housing also broke. Price for the housing and shaft are about $1000. I think I will also replace bearings and races. It's a tough call when the 306's can be bought for less than that, I just can't bring myself to scrap the mower. It is in great shape and has done a lot of mowing for me.