843 Gearcase Gear Damage

[Auggie]

Bought an old 843 and discovered the outer bearings on the input and output shaft in one gearbox were blown and things have been rattling around for at least a little while. Finally got the gearcase off.

What do y'all think about this damage on the edges of the output gears? seems like I could get away with putting it back in, but I'd like some other opinions. These gears aren't cheap

 

[Wayne440]

I respectfully offer these questions for your consideration as food for thought- (1) how long do you want the machine to last after your repair? (2) how long will it take to tear the machine back down for a similar repair when it is eventually needed? (3) does downtime create issues for you (lost revenue, customer dis-satisfaction etc.)or not?

 

[Auggie]

I respectfully offer these questions for your consideration as food for thought- (1) how long do you want the machine to last after your repair? (2) how long will it take to tear the machine back down for a similar repair when it is eventually needed? (3) does downtime create issues for you (lost revenue, customer dis-satisfaction etc.)or not?

Thanks those are the right questions to ask. This is for personal and light-duty farm use. Mostly using as an off road 'forklift' moving sacs of grain and sometimes logs around the property. Not pushing tons of dirt but I do have some upcoming projects for it.

I'd rather not do this again... so it's sort of a question of potential failure under light-medium duty conditions and failure is just a major pita for me but I don't have customers relying on me as of now.

I know the main concern would be a broken tooth. As you can see, about 10-15% of each tooth is compromised on both pieces.

there's a used large gear on ebay for 560 which I might get, but they don't even have a current part number for that smaller input shaft. Not sure what a repair would look like

 

[Wayne440]

Thanks those are the right questions to ask. This is for personal and light-duty farm use. Mostly using as an off road 'forklift' moving sacs of grain and sometimes logs around the property. Not pushing tons of dirt but I do have some upcoming projects for it.

I'd rather not do this again... so it's sort of a question of potential failure under light-medium duty conditions and failure is just a major pita for me but I don't have customers relying on me as of now.

I know the main concern would be a broken tooth. As you can see, about 10-15% of each tooth is compromised on both pieces.

there's a used large gear on ebay for 560 which I might get, but they don't even have a current part number for that smaller input shaft. Not sure what a repair would look like

I claim zero expertise (proceed at your own risk)- but if it was my machine, I would replace both gears with "better" if not new parts or go ahead and run the two damaged gears. I do not believe you will gain much, if any tooth contact area by replacing only one gear. But the pictures may not give me a valid point from which to say. IF you decide to put the worn gears back in, a little work on the edges to remove burrs or pieces that might chip off might be worth consideration.

 

[Auggie]

I claim zero expertise (proceed at your own risk)- but if it was my machine, I would replace both gears with "better" if not new parts or go ahead and run the two damaged gears. I do not believe you will gain much, if any tooth contact area by replacing only one gear. But the pictures may not give me a valid point from which to say. IF you decide to put the worn gears back in, a little work on the edges to remove burrs or pieces that might chip off might be worth consideration.

Yes, thanks, I found replacement gears but the guy wants $1600 for the pair which feels steep... I took them to a machinist friend and he felt pretty good about running them, but said the same as you to file off any burrs. My biggest concern is probably a piece of metal chipping off and blowing up a bearing again... Not too many great options for moving forward

 

[flyerdan]

Yes, thanks, I found replacement gears but the guy wants $1600 for the pair which feels steep... I took them to a machinist friend and he felt pretty good about running them, but said the same as you to file off any burrs. My biggest concern is probably a piece of metal chipping off and blowing up a bearing again... Not too many great options for moving forward

You should be able to find the part number on the Bobcat Online Parts catalog. I think it's 6558271, it's NLA but you might find one on ebay.
If you do decide to reuse the gears, clean all the loose stuff with a wire wheel and burnish the rough edges down; I'd probably use a 2" roloc about 80 grit. Put a good moly grease additive in, that should help reduce spalling considerably.
If there is room, I would seriously consider putting in a good rare earth magnet, like you can get at American Science & Surplus, that should trap any powdered metal or spall frags so they can't circulate into the bearings.

 

[Auggie]

You should be able to find the part number on the Bobcat Online Parts catalog. I think it's 6558271, it's NLA but you might find one on ebay.
If you do decide to reuse the gears, clean all the loose stuff with a wire wheel and burnish the rough edges down; I'd probably use a 2" roloc about 80 grit. Put a good moly grease additive in, that should help reduce spalling considerably.
If there is room, I would seriously consider putting in a good rare earth magnet, like you can get at American Science & Surplus, that should trap any powdered metal or spall frags so they can't circulate into the bearings.

Thanks flyerdan I will do all those things! Great advice
that's the correct part number, and there's 1 on ebay for $900. Together with the $600 large gear I'll probably take by chances by burnishing what I have, using the methods you suggested. A rare earth magnet is a good idea too.