No power to right back wheel on 763

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adventures

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I have a 763 that has been fairly maint free. I bought it used. When I went to use it yesterday I noticed it was hard to steer. I thought it was because of the mud I was in then I noticed that only the front right tire was spinning in the mud. The back tire wasn't moving (It will roll, not locked up - just not "driven" if that makes sense) I am not very mechanical but was hoping it might be something simple like a chain broken or off sprocket. I'm justing looking for a place to start before turning it over to mechanics. Thanks
 

skidsteer.ca

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likely a broken chain. However they are endless and require removing sprockets in the chain case to replace fromwhat I'm told
Sprockets and hubs are press fit to the axel and rarely come off, although I had a hub bolt (holds hub on axel) come loose once.
Ken
 

skidboy

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The sprocket is welded to a hub,i think that the fact that the wheel turns,it is more likely that the weld has let go,i have found this on a few machines
 

adventures

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The sprocket is welded to a hub,i think that the fact that the wheel turns,it is more likely that the weld has let go,i have found this on a few machines
Thank you guys for your info. When I get into it this week I'll let you guys know what is found. Thanks again. Kyle
 

adventures

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Thank you guys for your info. When I get into it this week I'll let you guys know what is found. Thanks again. Kyle
One more quick question. If the weld let go is it a matter of re-welding (I know some excellent welders!) or a total replacement of the hub? Thanks Kyle
 

skidsteer.ca

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One more quick question. If the weld let go is it a matter of re-welding (I know some excellent welders!) or a total replacement of the hub? Thanks Kyle
Is there a large bolt in the center of the wheel. If so that is what holds your hub to the axel. I'm pretty sure there is a taper on the axel with a keyway in it and the hub and this large bolt holds the hub on the taper. Same goes for the sprocket on the inside end of the axel.
Ken
 

skidboy

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Is there a large bolt in the center of the wheel. If so that is what holds your hub to the axel. I'm pretty sure there is a taper on the axel with a keyway in it and the hub and this large bolt holds the hub on the taper. Same goes for the sprocket on the inside end of the axel.
Ken
Yes the sprocket is bolted to the axle,but it simply pulls of the axle(of a spline) and yes a good welder can re-weld the hub back onto the sprocket,be carefull not to SHRINK the hub in the process as it may be difficult to refit to the axle. A good welder will be aware of this.
 

farmboy55

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Yes the sprocket is bolted to the axle,but it simply pulls of the axle(of a spline) and yes a good welder can re-weld the hub back onto the sprocket,be carefull not to SHRINK the hub in the process as it may be difficult to refit to the axle. A good welder will be aware of this.
Skidboy if you've never pulled a wheel hub off your Bobcat, it takes a BIG Heavy Duty pulled & big hammer. I built one out of 1" flat stock and had to be it up. Hit the hub with a slegde hammer and it flew 6 ft across the shop. So becarefull. where are you located? dennis
 

skidboy

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Skidboy if you've never pulled a wheel hub off your Bobcat, it takes a BIG Heavy Duty pulled & big hammer. I built one out of 1" flat stock and had to be it up. Hit the hub with a slegde hammer and it flew 6 ft across the shop. So becarefull. where are you located? dennis
If you leave the bolt undone about 3 turns it will leave enough room to break the taper ,but will leave you shin intact.
 

skidsteer.ca

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If you leave the bolt undone about 3 turns it will leave enough room to break the taper ,but will leave you shin intact.
I'm sorry but I don't see where there would be a broken weld involved. Both the sprocket and the hub are fit to a taper on the axel with a key (or spline). You would'nt weld it on.
Bobcat manual shows pressing the sprocket off the axel with a porta power , a short cylinder and several spacers. There is no room to swing a hammer in the chain case.
One or both sprockets need to be removed to install a new chain as it is endless/ has no master link.
Ken
 

skidboy

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I'm sorry but I don't see where there would be a broken weld involved. Both the sprocket and the hub are fit to a taper on the axel with a key (or spline). You would'nt weld it on.
Bobcat manual shows pressing the sprocket off the axel with a porta power , a short cylinder and several spacers. There is no room to swing a hammer in the chain case.
One or both sprockets need to be removed to install a new chain as it is endless/ has no master link.
Ken
I think that you will find that the porta power is pushing the axle through the bearing,as they are a tight fit on the axle.The sprocket is a push fit onto the axle.In the centre of the sprocket is a splined hub which is welded to the sprocket.It is not uncommen to see the weld let go and the wheel will just spin but there will be no locking up or spragging of the wheel as there will be if a chain is broken.
 

skidboy

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I think that you will find that the porta power is pushing the axle through the bearing,as they are a tight fit on the axle.The sprocket is a push fit onto the axle.In the centre of the sprocket is a splined hub which is welded to the sprocket.It is not uncommen to see the weld let go and the wheel will just spin but there will be no locking up or spragging of the wheel as there will be if a chain is broken.
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Tazza

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I think that you will find that the porta power is pushing the axle through the bearing,as they are a tight fit on the axle.The sprocket is a push fit onto the axle.In the centre of the sprocket is a splined hub which is welded to the sprocket.It is not uncommen to see the weld let go and the wheel will just spin but there will be no locking up or spragging of the wheel as there will be if a chain is broken.
It depends on what you are refering to, the outside hub or the inside sprocket..
From my experience with my 743 the sprocket inside is held on with a 1 1/8” bolt done up very f'n tight. With the bolt un-done the sprocket simple slides off (if you have broken the chain first). I relly can't see the weld breaking where the spline is cut and the sprocket is welded to it, but hey, you never know.
I do see a need for a porta power to press the outside hub off the axle, as it will rust a little making it hard to get it off. If you remove the outside hub to replace say an axle seal don't touch the internal sprocket, just un-do the external bolt and install a porta-power or even a small car bottle jack with the pump facing downwards and pump it up to get it to pop the axle hub off. Hitting it with a very large hammer will also do the job, but i like pressing it off, less paint get chipped off and having it fly at great speed across the shop and maybee hitting someones shin, no doubt the wifes.....
You won't know what is broken until you get time to have a look see what is going on the chaincase. Check the simple first, see if the outside hub is still intact, i'm sure you would notice if it wasn't as the wheel would probably be floping around.
Good luck with it
 

farmboy55

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It depends on what you are refering to, the outside hub or the inside sprocket..
From my experience with my 743 the sprocket inside is held on with a 1 1/8” bolt done up very f'n tight. With the bolt un-done the sprocket simple slides off (if you have broken the chain first). I relly can't see the weld breaking where the spline is cut and the sprocket is welded to it, but hey, you never know.
I do see a need for a porta power to press the outside hub off the axle, as it will rust a little making it hard to get it off. If you remove the outside hub to replace say an axle seal don't touch the internal sprocket, just un-do the external bolt and install a porta-power or even a small car bottle jack with the pump facing downwards and pump it up to get it to pop the axle hub off. Hitting it with a very large hammer will also do the job, but i like pressing it off, less paint get chipped off and having it fly at great speed across the shop and maybee hitting someones shin, no doubt the wifes.....
You won't know what is broken until you get time to have a look see what is going on the chaincase. Check the simple first, see if the outside hub is still intact, i'm sure you would notice if it wasn't as the wheel would probably be floping around.
Good luck with it
The keyway & key in the wheel hub would be a good place to start. I've never had one to break, what about you Tazza? Anything in possible> dennis
 

Tazza

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The keyway & key in the wheel hub would be a good place to start. I've never had one to break, what about you Tazza? Anything in possible> dennis
I haven't seen one, but thats because i have never owned a machine with a removable hub, they have all been welded to the axle making replacing seals a nightmare. Anything is possible though, start with the easy to access bits first.
 

jmatt20

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I haven't seen one, but thats because i have never owned a machine with a removable hub, they have all been welded to the axle making replacing seals a nightmare. Anything is possible though, start with the easy to access bits first.
i just pulled one of these apart. it was the rear on a 843 but the drawing above looks the same .after you take the big bolt off the inside you can just slide the splined sprocket off the end of the axle.you will need to take the bolt off the other side also to make room for the sprocket to slide off. on the machine i worked on the weld holding the sprocket to the splined hub was broken ,that is, in the drawing above part #3 was seperated into two pieces. the factory only welds these on one side. the part from bobcat cost about 450.00us so we had this one welded ,the shop where we had it done has a lathe so after it was welded on the inside they releaved the flush side and welded it on that side also. getting the wheel hub off the axle was another thing . i ended up pulling the axle out all together, that is hub, seal ,bearings ..... you have to pull the axle out to get the sprocket back on with the chain in place....you have to get the wheel hub off to put the seal i tried to press the hub off with my 20 ton press and it wouldn't budge. the welding shop had a 80 ton press and it did the job. we haven't reassembled the machine yet but as i see it the bearings on the outside go on first then the seal .put the wheel hub on and slide the axle in , the inside bearings go in then someone holds the sprocket with the chain on it in place, while another person pushes the axle in and rotates it to line up the splines, bolt everything up tight (sprocket bolt torque is about 450 ftlbs. i think) put the covers on ,put all of the hoses back on reinstall the stearing levers and trim panels and your up and running. well that only took 2 min. to type but i expect it'll take the beter part of a day to do.
 

jmatt20

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i just pulled one of these apart. it was the rear on a 843 but the drawing above looks the same .after you take the big bolt off the inside you can just slide the splined sprocket off the end of the axle.you will need to take the bolt off the other side also to make room for the sprocket to slide off. on the machine i worked on the weld holding the sprocket to the splined hub was broken ,that is, in the drawing above part #3 was seperated into two pieces. the factory only welds these on one side. the part from bobcat cost about 450.00us so we had this one welded ,the shop where we had it done has a lathe so after it was welded on the inside they releaved the flush side and welded it on that side also. getting the wheel hub off the axle was another thing . i ended up pulling the axle out all together, that is hub, seal ,bearings ..... you have to pull the axle out to get the sprocket back on with the chain in place....you have to get the wheel hub off to put the seal i tried to press the hub off with my 20 ton press and it wouldn't budge. the welding shop had a 80 ton press and it did the job. we haven't reassembled the machine yet but as i see it the bearings on the outside go on first then the seal .put the wheel hub on and slide the axle in , the inside bearings go in then someone holds the sprocket with the chain on it in place, while another person pushes the axle in and rotates it to line up the splines, bolt everything up tight (sprocket bolt torque is about 450 ftlbs. i think) put the covers on ,put all of the hoses back on reinstall the stearing levers and trim panels and your up and running. well that only took 2 min. to type but i expect it'll take the beter part of a day to do.
make that the rear on a 864, and why can't i get paragraphs???
 

Tazza

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make that the rear on a 864, and why can't i get paragraphs???
For paragraphs you need to go into you're profile and check the box that says use HTML free text box. When done, you can have paragraphs.
As you said earlier, a 5 minute typing job would indeed take the best part of a day to do!!! I have replaced rear axle seals on 2 743's, neither were fun. When i did them though, the machine was bare so i could hand the chain case up so gravity held the chains and sprockets for me. It was still a nightmare, but no where near as bad when still together. Bobcat service sure earns their money replacing seals and rear drive gears.
 

Fishfiles

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True that the Bobcat drive chains have no master link , but master links are available in full and half links from a supply house , so if the bearings and sprocket are still good , you can replace or repair the chain without removing the sprocket , also like someone mentioned the chain can be bought after market also and the price is about 1/3 of the dealers pricing
 
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