743 chain replacement, axle, bearing, and other questions.

[Fefanatic]

Hi, I have a 743 with a broken chain on the right rear wheel. I pulled the cover, drained the fluid and found the broken chain in the bottom of the case. I jacked the unit up, removed the tires and wheels, and checked end play on all four axles. The axle with the damaged chain has about 1/16" play. I did not measure exactly as it was obvious it was way out of spec. I removed the axle and the outer bearing stayed inside the axle tube as the seal did not come out. I used a porta power to push the axle out. Once out I could see that the race on the outer bearing was scored from debris. I removed the gear from the case and it looks worn but might be serviceable. I already ordered a new chain, seals, and gaskets from Bobcat and they will be here Wednesday. There is so much debris in the bottom of the chain case that I decided to pull all axles to clean and reseal the whole lower unit. Once the damaged axle was removed there was a accumulation of material laying on the bottom of the tube for the full length. If it is in this tube it will be in all the others. The chain case oil was milky from water contamination. There isn't any rust on chain or gears so I am not sure where the water came from. The seals are not leaking so I would think that if it wouldn't allow oil to escape then it wouldn't allow water to enter. I did use a pressure washer to clean this thing before I started working on it but that wouldn't have caused the milky condition. This is the first Bobcat I have ever worked on. I bought this from a relative (I know) and it was represented in better condition than it is. Here are some questions I have in doing these repairs. I am concerned about the outer bearing coming off the axle when the axle was pulled. It is supposed to be pressed onto the axle and it seemed to come off too easy. There isn't any indication on the bearing seat surface that indicates it has been spinning on the axle. Should I be concerned if it doesn't press on tightly? The gear had some nicks but didn't show a lot of wear. Replacement gears would be around $480.00 each according to Bobcat and I am not wanting to dump that kind of money into the machine. What's the opinion on a decent set of used gears? I most likely will replace all bearings on all axles. It seems that I can buy the bearings without races since the Bobcat takes a different race than what is normally supplied with bearing sets. I have been reading the service manual and it calls from some bolts to be tightened to 500 ft lbs. Is that correct or possibly a typo? I also noticed that the broken chain had slid over to the left side and had been interfering with the left rear wheel chain. The chain has mashed spots on the chain ends but it doesn't look damaged to the point of replacing. Should I replace it anyway? Space is at a premium on working on this machine. I was looking at the 20 bolts that attach the chain case to the upper half of the skid steer. Would removing those 20 bolts and removing the hydraulic lines free the whole lower unit from the upper or are there other things attached that would make it not worth the effort? I know that splitting a bearing race can be used to drive a new seal into the axle tube and I already split one for that purpose. I saw the tool that is designed to install the inner races but I am thinking that I might be able to use a porta power to install them. I will have to make a bracket to push against but I think I can do that. This has what I think is Teflon chain guides. Chain deflection on all chains is around 1" or so. The manual says to remove a link if necessary to tighten in. There is not a full link length of slack so removing a link is not possible. I just don't know how much slack is acceptable. Any advice here would be appreciated. My main concern is the axle bearing coming off instead of pushing out the seal. Would that be a problem in the future. The other concern is whether it would be worth the effort to remove the whole chain from the upper section of the loader. Since this is the first time I have tackled something like this any advice will be taken seriously. I want to do this only once. Wow, this was a lot of babbling here

 

[Fefanatic]

I answered my own question about the axle. The new bearing will be a press fit so the axle is OK.

 

[Madbobcater743]

I answered my own question about the axle. The new bearing will be a press fit so the axle is OK.

Hey fefanatic- I too am the proud owner of a 743. From what I can tell everything needs work on my machine. By any chance could you take a few pictures or videos of what you do and how you do it? Do you have all of your service/parts/operators books on the machine? Best of luck!

 

[Fe Fanatic]

Hey fefanatic- I too am the proud owner of a 743. From what I can tell everything needs work on my machine. By any chance could you take a few pictures or videos of what you do and how you do it? Do you have all of your service/parts/operators books on the machine? Best of luck!

This is a learning curve for me. I am getting good advice from my local Bobcat parts guy and right now am waiting on parts to come in. So far what I have learned is the machine is rear heavy and I almost got hurt finding it out. I removed the bucket and raised the lift arm up and blocked it. I put the unit on jack stands and started the tear down. I removed the front panel with the control arms and put them aside. I removed the front top plate to the chain case but the back plate was pretty tight under the pump frame mount. I removed that mount and that allowed me to lift the rear plate up enough to clear the parking brake assembly. With that pump mount out I had plenty of room to access the chain and gears in the rear of the chain case. It will be a pain to reach but doable. It saves the process of removing the engine. Since the chain was broken and I had the unit up on stands I faced a dilemma of getting the axle bolt loose. I put a 1 1/8" box end wrench on the bolt and used a floor jack to turn the tire to loosen the bolt. I placed the jack under one of the tires lugs and jacked it up. The tire turned and the bolt came loose easily that way. The chain was wedged under the left rear chain and sprocket and it took some coaxing to get it out. That chain shows some mashed end links and I won't make a decision on its replacement until I remove it and check for stiffness or excess play. I plan to use the hydraulics to get the rest of the axle bolts out. The unit still runs and I didn't have to disconnect any hydraulics so I plan to start the motor and wedge the wrench on the bolts and use the drive motors to turn the gears and loosen the bolts. I do not plan to do this without someone there to help out in case of emergency. When I talk about the unit being rear heavy I had a incident while working on the motor. I removed the four tires and wheels and left the arm up in the raised position. Since I am waiting on parts I decided to change the engine oil. I had the back engine cover open and was fighting the drain hose coming from the bottom of the block (rusted and would not come loose). I pushed a little hard down on a wrench and the whole machine tilted backwards. I was running for my life at that point. The only thing that kept the machine from falling off the jack stands and landing on the concrete was the rear door. The machine came back and the door hit the concrete floor and stopped all movement. It took a floor jack to jack the machine back onto the front stands. Once the machine was stable again I placed jackstands under the rear pan to stop any future tipping. I seriously believe if that door had not stopped the movement I would have been pinned under the machine. Lesson well learned. I didn't think of taking any pictures but I will for future reference. I could not save the top plate gaskets so I ordered new gaskets also. I think that my biggest problem in reassembly will be reinstalling the axle seals. I cut a bearing race in half to try to drive them in but something tells me that it won't be that simple. That's why I made my first post hoping someone has already been here and done this. FWIW, on a side note I think I need to learn HTML to be able to format these posts into paragraphs.

 

[Madbobcater743]

This is a learning curve for me. I am getting good advice from my local Bobcat parts guy and right now am waiting on parts to come in. So far what I have learned is the machine is rear heavy and I almost got hurt finding it out. I removed the bucket and raised the lift arm up and blocked it. I put the unit on jack stands and started the tear down. I removed the front panel with the control arms and put them aside. I removed the front top plate to the chain case but the back plate was pretty tight under the pump frame mount. I removed that mount and that allowed me to lift the rear plate up enough to clear the parking brake assembly. With that pump mount out I had plenty of room to access the chain and gears in the rear of the chain case. It will be a pain to reach but doable. It saves the process of removing the engine. Since the chain was broken and I had the unit up on stands I faced a dilemma of getting the axle bolt loose. I put a 1 1/8" box end wrench on the bolt and used a floor jack to turn the tire to loosen the bolt. I placed the jack under one of the tires lugs and jacked it up. The tire turned and the bolt came loose easily that way. The chain was wedged under the left rear chain and sprocket and it took some coaxing to get it out. That chain shows some mashed end links and I won't make a decision on its replacement until I remove it and check for stiffness or excess play. I plan to use the hydraulics to get the rest of the axle bolts out. The unit still runs and I didn't have to disconnect any hydraulics so I plan to start the motor and wedge the wrench on the bolts and use the drive motors to turn the gears and loosen the bolts. I do not plan to do this without someone there to help out in case of emergency. When I talk about the unit being rear heavy I had a incident while working on the motor. I removed the four tires and wheels and left the arm up in the raised position. Since I am waiting on parts I decided to change the engine oil. I had the back engine cover open and was fighting the drain hose coming from the bottom of the block (rusted and would not come loose). I pushed a little hard down on a wrench and the whole machine tilted backwards. I was running for my life at that point. The only thing that kept the machine from falling off the jack stands and landing on the concrete was the rear door. The machine came back and the door hit the concrete floor and stopped all movement. It took a floor jack to jack the machine back onto the front stands. Once the machine was stable again I placed jackstands under the rear pan to stop any future tipping. I seriously believe if that door had not stopped the movement I would have been pinned under the machine. Lesson well learned. I didn't think of taking any pictures but I will for future reference. I could not save the top plate gaskets so I ordered new gaskets also. I think that my biggest problem in reassembly will be reinstalling the axle seals. I cut a bearing race in half to try to drive them in but something tells me that it won't be that simple. That's why I made my first post hoping someone has already been here and done this. FWIW, on a side note I think I need to learn HTML to be able to format these posts into paragraphs.

Hey man its going to be a learning curve for me too!------------------------------------------------------------ I don't have a garage. But really need to start my teardown asap. I ordered a cheep enclosure from harbor freight. I plan on taking my FOPS off and working under there here in what they are saying is going to be a snowy massachusetts this winter. ---------------------------------------------------------------- Mine's at the dealer now getting the chain case drained and re gasketed. I need to do the speed control plate, have a leaky injector, need to drain water and hydraulic oil as well. ----------------------------------- Its funny that you say that happened to you like that cause when I first got my 743 with the 1702 in it we put the arms up while my buddy was getting to the linkage i was changing oil and chasing leaks inside the back door. We didn't jack it up and the back door kepts the machine from falling over.---------- Boy was that a huge awaking. You have your manuals? There are some real nice guys on here that hooked me up and i can send you what I have.-------------------------------------------------------------------

 

[Fefanatic]

Hey man its going to be a learning curve for me too!------------------------------------------------------------ I don't have a garage. But really need to start my teardown asap. I ordered a cheep enclosure from harbor freight. I plan on taking my FOPS off and working under there here in what they are saying is going to be a snowy massachusetts this winter. ---------------------------------------------------------------- Mine's at the dealer now getting the chain case drained and re gasketed. I need to do the speed control plate, have a leaky injector, need to drain water and hydraulic oil as well. ----------------------------------- Its funny that you say that happened to you like that cause when I first got my 743 with the 1702 in it we put the arms up while my buddy was getting to the linkage i was changing oil and chasing leaks inside the back door. We didn't jack it up and the back door kepts the machine from falling over.---------- Boy was that a huge awaking. You have your manuals? There are some real nice guys on here that hooked me up and i can send you what I have.-------------------------------------------------------------------

So far it's been crickets here. I will ask one more question and if I can't get a response then I won't bother anyone here again. What's the best way to remove the seal wear sleeves from the axles?

 

[Madbobcater743]

So far it's been crickets here. I will ask one more question and if I can't get a response then I won't bother anyone here again. What's the best way to remove the seal wear sleeves from the axles?

Hey man shoot me an email. I might have a few manuals that might help you.

 

[Fefanatic]

Hey man shoot me an email. I might have a few manuals that might help you.

I have a .pdf service manual. It lacks some details but has enough information to get the job done. FWIW, I figured out how to remove the wear sleeves. I heated the sleeves with a cutting torch and tapped the cut valve. It blew the side out of the sleeve and it popped off. If you do it quickly like I did the axle was still cool enough to handle by hand.

 

[Tazza]

I have a .pdf service manual. It lacks some details but has enough information to get the job done. FWIW, I figured out how to remove the wear sleeves. I heated the sleeves with a cutting torch and tapped the cut valve. It blew the side out of the sleeve and it popped off. If you do it quickly like I did the axle was still cool enough to handle by hand.

Geez, glad you weren't pancaked under your machine.
As you have found out, the rear is the heaviest part, and you need to put a jack under the rear to stop it tilting back, more so if there is no bucket on the machine.
I think you'd be surprised at how much wear you can have on the sprockets before they become un-serviceable. As long as it has teeth and you can flatten the surface that the bearing sits on, it will be fine. You may need to machine the washers to take up any axle end float.

 

[Fefanatic]

Geez, glad you weren't pancaked under your machine.
As you have found out, the rear is the heaviest part, and you need to put a jack under the rear to stop it tilting back, more so if there is no bucket on the machine.
I think you'd be surprised at how much wear you can have on the sprockets before they become un-serviceable. As long as it has teeth and you can flatten the surface that the bearing sits on, it will be fine. You may need to machine the washers to take up any axle end float.

For some reason I get script errors trying to use HTML. I have decided to replace all chains as one is stiff in a couple of spots and I am already there as far as dis assembly. I bought the broken chain replacement from Bobcat and it was over $150.00 for a 4' section. I would like to find another source and I have found different outlets for chain. What do you recommend for replacement? The way I figure it the other rear chain will be $150.00 and I haven't checked front chain prices but I'd bet around $200.00 each. I have seen #80H chain in the $60-100 range for a 10' section. Is anyone using these chains instead of the Bobcat. Even Diamond brand chain that I did get from Bobcat is considerably cheaper from independent dealers.

 

[walio123]

For some reason I get script errors trying to use HTML. I have decided to replace all chains as one is stiff in a couple of spots and I am already there as far as dis assembly. I bought the broken chain replacement from Bobcat and it was over $150.00 for a 4' section. I would like to find another source and I have found different outlets for chain. What do you recommend for replacement? The way I figure it the other rear chain will be $150.00 and I haven't checked front chain prices but I'd bet around $200.00 each. I have seen #80H chain in the $60-100 range for a 10' section. Is anyone using these chains instead of the Bobcat. Even Diamond brand chain that I did get from Bobcat is considerably cheaper from independent dealers.

I had a similar case years ago. My friend bought a chains of some agricultural machine. Kind of seemed pretty cool, even lateral connections were thicker than those used from Bobcat. Change them and after one month of employment had to change not only the chains - all sprockets were damaged.f you know what brand and what chains hardness use Bobcat, if you find a dealer of this brand buy them. In all cases will be more cheaper.Whenever I have to redo something, trying to get in touch directly with the dealer who presents it. Particularly in engines I've seen prices up 10 - 60% higher in Bobcat dealer than the Kubota or Deutz or Isuzu dealer.Each dealer operates for profit. Thats life. Just find the right one.

 

[Fefanatic]

I had a similar case years ago. My friend bought a chains of some agricultural machine. Kind of seemed pretty cool, even lateral connections were thicker than those used from Bobcat. Change them and after one month of employment had to change not only the chains - all sprockets were damaged.f you know what brand and what chains hardness use Bobcat, if you find a dealer of this brand buy them. In all cases will be more cheaper.Whenever I have to redo something, trying to get in touch directly with the dealer who presents it. Particularly in engines I've seen prices up 10 - 60% higher in Bobcat dealer than the Kubota or Deutz or Isuzu dealer.Each dealer operates for profit. Thats life. Just find the right one.

Now I know more about roller chain than I really ever wanted to know. It looks like I just need a good quality chain and that's what I plan to use. I'm waiting on a response from Diamond for a part number of the chain I now have. I don't mind paying a little extra for a factory part but 3-4 times the money is a little extreme.

 

[Fefanatic]

Now I know more about roller chain than I really ever wanted to know. It looks like I just need a good quality chain and that's what I plan to use. I'm waiting on a response from Diamond for a part number of the chain I now have. I don't mind paying a little extra for a factory part but 3-4 times the money is a little extreme.

I couldn't get any information from the Diamond people. I contacted the Tsubaki folks and after a short conversation I went with their Super 80H chain. Pricey but not as pricey as the Bobcat prices. I will post how it looks and if there are any install problems. I expect it her around Saturday since Merry Christmas is Friday. I won't know how it holds up until it has a few hours on it.

 

[walio123]

I couldn't get any information from the Diamond people. I contacted the Tsubaki folks and after a short conversation I went with their Super 80H chain. Pricey but not as pricey as the Bobcat prices. I will post how it looks and if there are any install problems. I expect it her around Saturday since Merry Christmas is Friday. I won't know how it holds up until it has a few hours on it.

It often happens to me to write to the manufacturer and he answers me to turn to the dealer in Bulgaria. How to explain that the dealer wants me his 3-4-5 times higher than its price? As Bobcat they know how to hide information and keep it confidential. Never reluctant to share it.

 

[7LBSSMALLIE]

It often happens to me to write to the manufacturer and he answers me to turn to the dealer in Bulgaria. How to explain that the dealer wants me his 3-4-5 times higher than its price? As Bobcat they know how to hide information and keep it confidential. Never reluctant to share it.

without readining the 5 miles of post. a bit of advice. 743 full chain case rebuild is a bit of a pain . can be done easy by separate main frame from chaincase. seems extreme. but back in the day . this was how it was done. serious liftining eguipment is reguired load needs safe. but in reality you got like 16 bolts securining main frame to chaincase. I'm talking half a day fully separated main frame from case. now got something you can deal with. a drive case sitting on four tires and brake removed can be pushed by hand.. yes very intimadteing. but seriously options are try to pry stat up ? to access rear chains sprockets and race. ive done both. in frame or outta frame. if doing ax brgs races etc split it save a lotta time and agravation

 

[Fefanatic]

without readining the 5 miles of post. a bit of advice. 743 full chain case rebuild is a bit of a pain . can be done easy by separate main frame from chaincase. seems extreme. but back in the day . this was how it was done. serious liftining eguipment is reguired load needs safe. but in reality you got like 16 bolts securining main frame to chaincase. I'm talking half a day fully separated main frame from case. now got something you can deal with. a drive case sitting on four tires and brake removed can be pushed by hand.. yes very intimadteing. but seriously options are try to pry stat up ? to access rear chains sprockets and race. ive done both. in frame or outta frame. if doing ax brgs races etc split it save a lotta time and agravation

Yep, I asked that question in another post in this thread but didn't get a response. I.m already there with the tear down so it's a little late to split the unit in half. I'm now waiting on chain and concentrating on making tools to reinstall the axles. I decided to install all axles and gears and then put the chains on. I plan to make a bar that will bolt to the lugs on the axles and wend a big nut in the center. That way I can use a wrench to hold the nut on the inside ends of the axles and use a torque wrench to tighten the bolts from the outside. The wrench will wedge against the floor of the chain case and the axle will be turned with a torque wrench to torque it down. Shouldn't be a problem without the chains installed. I still have to make a tool to press the new seal repair sleeves in place and plan to drill a hole in a block of wood to use as a press. I've done that with front balancer sleeves on car engines and I think that should work here also. I already have a 3" piece of flat iron that I plan to drill and tap for installing the inner bearing races. A little allthread and another flat piece on the outer axle tube should do the trick. Will post if it works.

 

[Tazza]

Yep, I asked that question in another post in this thread but didn't get a response. I.m already there with the tear down so it's a little late to split the unit in half. I'm now waiting on chain and concentrating on making tools to reinstall the axles. I decided to install all axles and gears and then put the chains on. I plan to make a bar that will bolt to the lugs on the axles and wend a big nut in the center. That way I can use a wrench to hold the nut on the inside ends of the axles and use a torque wrench to tighten the bolts from the outside. The wrench will wedge against the floor of the chain case and the axle will be turned with a torque wrench to torque it down. Shouldn't be a problem without the chains installed. I still have to make a tool to press the new seal repair sleeves in place and plan to drill a hole in a block of wood to use as a press. I've done that with front balancer sleeves on car engines and I think that should work here also. I already have a 3" piece of flat iron that I plan to drill and tap for installing the inner bearing races. A little allthread and another flat piece on the outer axle tube should do the trick. Will post if it works.

That is basically how I did mine too. I got a piece of angle iron and welded water pipe to it to bolt to the lugs, used a spanner inside the chain case and tighten from the outside. I didn't use a torque wrench, I just hauled on them though.
As for the wear sleeves, I installed mine with the new bearing cone. Slip the wear sleeve on the axle, slide the bearing cone on to the axle and seat the bearing and sleeve in one hit. I used a piece of water pipe for this too, it slid over the axle nicely and worked as a hammer, simply slide up and down over the axle and hit the bearing. It worked really well for me.
As for adding chains after the axles and sprockets are in, this will only work if you get chain and master links and not pre-made ones.

 

[Fefanatic]

That is basically how I did mine too. I got a piece of angle iron and welded water pipe to it to bolt to the lugs, used a spanner inside the chain case and tighten from the outside. I didn't use a torque wrench, I just hauled on them though.
As for the wear sleeves, I installed mine with the new bearing cone. Slip the wear sleeve on the axle, slide the bearing cone on to the axle and seat the bearing and sleeve in one hit. I used a piece of water pipe for this too, it slid over the axle nicely and worked as a hammer, simply slide up and down over the axle and hit the bearing. It worked really well for me.
As for adding chains after the axles and sprockets are in, this will only work if you get chain and master links and not pre-made ones.

I didn't think about using a bearing for the press. Since they are pressed to the axle did you put the seal on also before driving the sleeve and bearing in place?
As far as the chain goes I bought bulk for the remaining 3 wheels. The chain I purchased from Bobcat came with a master link and I have to thread it on also. I don't have a chain pin press and thought I would just use a wire welder and weld the pins. The only down side to that might be I would weaken the hardened side link.
The new chain won't be here until Wednesday so I have time to make the decision on what to do.
I also noticed wear in the Teflon chain guides. I am going to order them also. What the heck, another few dollars isn't going to make the difference.

 

[Madbobcater743]

I didn't think about using a bearing for the press. Since they are pressed to the axle did you put the seal on also before driving the sleeve and bearing in place?
As far as the chain goes I bought bulk for the remaining 3 wheels. The chain I purchased from Bobcat came with a master link and I have to thread it on also. I don't have a chain pin press and thought I would just use a wire welder and weld the pins. The only down side to that might be I would weaken the hardened side link.
The new chain won't be here until Wednesday so I have time to make the decision on what to do.
I also noticed wear in the Teflon chain guides. I am going to order them also. What the heck, another few dollars isn't going to make the difference.

any pics brah>?