773G Axle seals and bearings

Help Support SkidSteer Forum:

cwhitten

Member
Joined
May 22, 2009
Messages
7
I have two axle seals leaking and want to replace all four and the bearings. I have the service manual, but can anyone give me any input on how to press in the new inside bearing cup/race. I'm primarily concerned about not having the correct tools for pressing out the axle, pulling the hub, removing and replacing bearing race. I think I can handle make a tool for pulling and driving in the seal. I like to know what I'm getting into before I get started. Thanks in advance for any input.
 

Tazza

Moderator
Staff member
Joined
Dec 7, 2004
Messages
16,829
Its not all that hard
Drain the chain case by removing the plug that is under the back, its covered with a plate with 3 screws. remove the wheels and block it up. Remove the covers on the chain case, there are 2. You can do this second part 2 ways, one with the machines power or remove the hydraulic motors to allow them to rotate, this is your choice. Use a 1 1/8" spanner on the bolts inside the chain case, use the drive to crack the bolts or make a jig with a length of pipe to slide over the wheel nuts.
Once the bolts are all cracked you will need 2 good sized hydraulic jacks to get the hubs off for starters. Loosen the bolts on the hubs, put 2 bottle jacks behind the hub, one each side with the pump facing down wards, pump them up then either strike the head of the bolt with a copper hammer or the back of the hub, it should pop free. Don't fully remove the hubs yet.
You can use the hydraulics to spin the bolts all the way free or by hand. Either way, remove the bolts. You then use a bottle jack behind the hubs and push the axle and seals/bearings out. The sprockets will slip off the axles. Now use a length of bar and knock the bearing cups out, you can get them all if you have both rear or front axles out. To re-install you can machine a tool to pull them in with a length of threaded rod, tighten it up to pull them into place, simple job with a lathe. I used a piece of water pipe to seat the bearings on the axles, i used a welder and air chisel to get the bearings off.
Slide the axle in, grease the bearings!!! line the sprocket up on the axle and slide it all together. Put loctite on the bolt and tighten up! Check for end float, there should be no play with new bearings.
Do the same for all 4
You may need to make a seal installation tool too, i made one that i slide on the axle and slip a bolt through and tighten up to pull it in, no bashing required, very simple to make with a lathe.
I hope that gives you an idea whats involved. If you have a lathe and time, you can do it easily.
 
OP
OP
C

cwhitten

Member
Joined
May 22, 2009
Messages
7
Its not all that hard
Drain the chain case by removing the plug that is under the back, its covered with a plate with 3 screws. remove the wheels and block it up. Remove the covers on the chain case, there are 2. You can do this second part 2 ways, one with the machines power or remove the hydraulic motors to allow them to rotate, this is your choice. Use a 1 1/8" spanner on the bolts inside the chain case, use the drive to crack the bolts or make a jig with a length of pipe to slide over the wheel nuts.
Once the bolts are all cracked you will need 2 good sized hydraulic jacks to get the hubs off for starters. Loosen the bolts on the hubs, put 2 bottle jacks behind the hub, one each side with the pump facing down wards, pump them up then either strike the head of the bolt with a copper hammer or the back of the hub, it should pop free. Don't fully remove the hubs yet.
You can use the hydraulics to spin the bolts all the way free or by hand. Either way, remove the bolts. You then use a bottle jack behind the hubs and push the axle and seals/bearings out. The sprockets will slip off the axles. Now use a length of bar and knock the bearing cups out, you can get them all if you have both rear or front axles out. To re-install you can machine a tool to pull them in with a length of threaded rod, tighten it up to pull them into place, simple job with a lathe. I used a piece of water pipe to seat the bearings on the axles, i used a welder and air chisel to get the bearings off.
Slide the axle in, grease the bearings!!! line the sprocket up on the axle and slide it all together. Put loctite on the bolt and tighten up! Check for end float, there should be no play with new bearings.
Do the same for all 4
You may need to make a seal installation tool too, i made one that i slide on the axle and slip a bolt through and tighten up to pull it in, no bashing required, very simple to make with a lathe.
I hope that gives you an idea whats involved. If you have a lathe and time, you can do it easily.
Tazza, Thanks for your help. I have the front axles/bearings out and everthing clean. I saved $10 per axle on the bearings. I went ahead and purchased the seals from my local Bobcat dealer. I will take pictures of the rear axle repair. Maybe I can help someone else out with some good pictures. Now, I have some other questions. 1.) When going downhill at full speed, I heard some chain slap. Could this be from side to side from axle end play? Sprocket wear? Should I put in a half link? How do I do this? How do I measure the chain slack? Can I do it without a chainbreaker? New chains are $125 and $115 each (front and rear). 2.) Since this machine has been run with low oil in the chaincase, I need to check the drive motor bearings. Right? How much end play is acceptable? Seals? The last thing that I want to happen is to refill the chaincase and have the motor shaft seals start pouring out oil. This is too much work to not do everything right the first time. 3.) What oil do you recomment to run in the chaincase. Bobcat oil is quite expensive (especially 9 gallons of it) I'm glad I decided to do this myself. It will be well worth it. Once I get everything back together, I will be wearing out the front plug checking the oil level almost everytime I use the machine. Thanks again.
 
OP
OP
C

cwhitten

Member
Joined
May 22, 2009
Messages
7
Its not all that hard
Drain the chain case by removing the plug that is under the back, its covered with a plate with 3 screws. remove the wheels and block it up. Remove the covers on the chain case, there are 2. You can do this second part 2 ways, one with the machines power or remove the hydraulic motors to allow them to rotate, this is your choice. Use a 1 1/8" spanner on the bolts inside the chain case, use the drive to crack the bolts or make a jig with a length of pipe to slide over the wheel nuts.
Once the bolts are all cracked you will need 2 good sized hydraulic jacks to get the hubs off for starters. Loosen the bolts on the hubs, put 2 bottle jacks behind the hub, one each side with the pump facing down wards, pump them up then either strike the head of the bolt with a copper hammer or the back of the hub, it should pop free. Don't fully remove the hubs yet.
You can use the hydraulics to spin the bolts all the way free or by hand. Either way, remove the bolts. You then use a bottle jack behind the hubs and push the axle and seals/bearings out. The sprockets will slip off the axles. Now use a length of bar and knock the bearing cups out, you can get them all if you have both rear or front axles out. To re-install you can machine a tool to pull them in with a length of threaded rod, tighten it up to pull them into place, simple job with a lathe. I used a piece of water pipe to seat the bearings on the axles, i used a welder and air chisel to get the bearings off.
Slide the axle in, grease the bearings!!! line the sprocket up on the axle and slide it all together. Put loctite on the bolt and tighten up! Check for end float, there should be no play with new bearings.
Do the same for all 4
You may need to make a seal installation tool too, i made one that i slide on the axle and slip a bolt through and tighten up to pull it in, no bashing required, very simple to make with a lathe.
I hope that gives you an idea whats involved. If you have a lathe and time, you can do it easily.
Tazza,
Thanks for your help. I have the front axles/bearings out and everthing clean. I saved $10 per axle on the bearings. I went ahead and purchased the seals from my local Bobcat dealer.
I will take pictures of the rear axle repair. Maybe I can help someone else out with some good pictures.
Now, I have some other questions.
1.) When going downhill at full speed, I heard some chain slap. Could this be from side to side from axle end play? Sprocket wear? Should I put in a half link? How do I do this? How do I measure the chain slack? Can I do it without a chainbreaker? New chains are $125 and $115 each (front and rear).
2.) Since this machine has been run with low oil in the chaincase, I need to check the drive motor bearings. Right? How much end play is acceptable? Seals? The last thing that I want to happen is to refill the chaincase and have the motor shaft seals start pouring out oil. This is too much work to not do everything right the first time.
3.) What oil do you recomment to run in the chaincase. Bobcat oil is quite expensive (especially 9 gallons of it)
I'm glad I decided to do this myself. It will be well worth it. Once I get everything back together, I will be wearing out the front plug checking the oil level almost everytime I use the machine. Thanks again.
 

Tazza

Moderator
Staff member
Joined
Dec 7, 2004
Messages
16,829
Tazza,
Thanks for your help. I have the front axles/bearings out and everthing clean. I saved $10 per axle on the bearings. I went ahead and purchased the seals from my local Bobcat dealer.
I will take pictures of the rear axle repair. Maybe I can help someone else out with some good pictures.
Now, I have some other questions.
1.) When going downhill at full speed, I heard some chain slap. Could this be from side to side from axle end play? Sprocket wear? Should I put in a half link? How do I do this? How do I measure the chain slack? Can I do it without a chainbreaker? New chains are $125 and $115 each (front and rear).
2.) Since this machine has been run with low oil in the chaincase, I need to check the drive motor bearings. Right? How much end play is acceptable? Seals? The last thing that I want to happen is to refill the chaincase and have the motor shaft seals start pouring out oil. This is too much work to not do everything right the first time.
3.) What oil do you recomment to run in the chaincase. Bobcat oil is quite expensive (especially 9 gallons of it)
I'm glad I decided to do this myself. It will be well worth it. Once I get everything back together, I will be wearing out the front plug checking the oil level almost everytime I use the machine. Thanks again.
F#$#%#'n thing!!! I typed a reply and it got eaten on me, i should learn to use the clipboard before posting! i'll do it again...
 

Tazza

Moderator
Staff member
Joined
Dec 7, 2004
Messages
16,829
F#$#%#'n thing!!! I typed a reply and it got eaten on me, i should learn to use the clipboard before posting! i'll do it again...
Ok, lets try this again shall we
Standard engine oil is all you need.
A little chain slap should be ok, if it constantly drags along the bottom of the chain case, thats not so good. The price on chain isnt that bad actually, i expected more. I would take the chains and sprockets out and look for excessive wear. You can take the sharp edge off the sprockets with a soft wheel on and angle grinder.
The motor bearings are actually part of the motor carrier. You remove the motor from it and you can pull the shaft and bearings, you will need a new seal though. If there is no end float i'd leave them alone. This carrier is also used to adjust your chains. This way you can set the same amount of slack front and back, it can slide back and forth then lock it in place with the internal bolts.
Hopefully that answers a few more questions, if you have more just yell! or if i missed anything....
 
OP
OP
C

cwhitten

Member
Joined
May 22, 2009
Messages
7
Ok, lets try this again shall we
Standard engine oil is all you need.
A little chain slap should be ok, if it constantly drags along the bottom of the chain case, thats not so good. The price on chain isnt that bad actually, i expected more. I would take the chains and sprockets out and look for excessive wear. You can take the sharp edge off the sprockets with a soft wheel on and angle grinder.
The motor bearings are actually part of the motor carrier. You remove the motor from it and you can pull the shaft and bearings, you will need a new seal though. If there is no end float i'd leave them alone. This carrier is also used to adjust your chains. This way you can set the same amount of slack front and back, it can slide back and forth then lock it in place with the internal bolts.
Hopefully that answers a few more questions, if you have more just yell! or if i missed anything....
Yeah, I typed for 15 minutes trying to think of everything that I wanted to ask. I clicked "post" and lost it. !@*!!!
I typed it in MS Word the next time.
The only thing that I forgot from my lost post was about the drain plug. Would you put in a new gasket/plug. Service manual says to replace everytime. Mine didn't appear to be leaking.
Thanks, I hope I will not need any other parts this weekend and I can finish.
 

skidsteer.ca

Well-known member
Joined
Jan 20, 2006
Messages
3,853
Yeah, I typed for 15 minutes trying to think of everything that I wanted to ask. I clicked "post" and lost it. !@*!!!
I typed it in MS Word the next time.
The only thing that I forgot from my lost post was about the drain plug. Would you put in a new gasket/plug. Service manual says to replace everytime. Mine didn't appear to be leaking.
Thanks, I hope I will not need any other parts this weekend and I can finish.
Yes , on long post always select the text and hit "control C" to copy it, the forum seem to time out and won't up load the post after you have pounded away forever, "save your work , save you sanity"
Ken
 

Tazza

Moderator
Staff member
Joined
Dec 7, 2004
Messages
16,829
Yes , on long post always select the text and hit "control C" to copy it, the forum seem to time out and won't up load the post after you have pounded away forever, "save your work , save you sanity"
Ken
Ken - so true!!!
I haven't installed a new plug before, i know i should but i was lazy. I cleaned up both the plug and chain case and gave it a small smear of silicone sealant then put the plug in. It has never leaked since, was about 12 months ago now.
 
OP
OP
C

cwhitten

Member
Joined
May 22, 2009
Messages
7
Well, I finished at 2:00am Saturday night. I'm still feeling the effects of doing too much in one day. I need to get more exercise. At the end of the summer would have been a better time to tackle this job.
It wasn't too bad. I had to use a little heat on one of the hubs. I will post some pics later.
I have a slight endplay on one of the front axles. I haven't measured it yet. I could remove material from the washer in the chaincase. Right? The material removal would have to be the same diameter as the axle splines. This would allow the sprocket hub to push on the bearing and suck up the final bit of endplay.
I will have to measure it. I'm not sure it is worth the effort (maybe .005 to .015). It is sooooo much better than the .250 end play that was there before.
Thanks, and I promise to post some pics of my bearing installer. Oh! And especially my calibrated 800 ft-lb torquing of the hub bolts!
 

Tazza

Moderator
Staff member
Joined
Dec 7, 2004
Messages
16,829
Well, I finished at 2:00am Saturday night. I'm still feeling the effects of doing too much in one day. I need to get more exercise. At the end of the summer would have been a better time to tackle this job.
It wasn't too bad. I had to use a little heat on one of the hubs. I will post some pics later.
I have a slight endplay on one of the front axles. I haven't measured it yet. I could remove material from the washer in the chaincase. Right? The material removal would have to be the same diameter as the axle splines. This would allow the sprocket hub to push on the bearing and suck up the final bit of endplay.
I will have to measure it. I'm not sure it is worth the effort (maybe .005 to .015). It is sooooo much better than the .250 end play that was there before.
Thanks, and I promise to post some pics of my bearing installer. Oh! And especially my calibrated 800 ft-lb torquing of the hub bolts!
You need to remove that end float. Remove the material from the washer, only the internal part though, leave the outer edge where it touches the sprocket. You don't want it moving or it will damage the bearings and seal, you will be back to square one.
For my bearings i made an adapter for a hydraulic pull ram, it pulls the bearing cups into place with ease. You can use threaded bar too. I also made a seal installation tool that you sit on the axle and put the hub bolt through and tighten it up. It pulls the seal into place easily too, no bashing with a hammer, just twist till its seated, simple!
The hubs sometimes are very tight and require heat, i haven't needed to do that yet, 2 BIG bottle jacks and a hammer did it for me.
 
Top