773 loose chains and replacement

[NoackBobcatGuy]

Hello, skidsteer owner newbie here. After renting skidsteers for years, I finally picked up a used 773 in decent shape, had to remove the control panel to fix a hydraulic leak and decided to open the chain case while I am in it. I have all 3 covers off at this point. It's missing the lock pin and the solenoid is empty which I'll replace and also drain and mop-out the oil and sludge from the case. Both left side chains have considerable play (compared with the right side chains) and the right-side chains have a good amount of play as well. Sprockets look good, no seal leaks etc. Front left driven sproket has been re-welded to the hub at some point in its previous life. So how do you know what is too much play vs it'll last a long time the way it is? I am seriously considering putting new chains on it, and looks like the cut existing chains and go the master link route is the easiest option to avoid removing the axles et al. I won't be using it on a daily basis however I like to keep my equipment and vehicles in top mechanical shape. If the chain breaks, then sproket damage (or worse) occurs so it seems like preventative maintenance installing new chains might be warranted. Thanks, Tim

 

[flyerdan]

There is a 773 service and parts book available in the manual thread, both can be quite helpful in figuring how things go and sourcing parts.

 

[NoackBobcatGuy]

There is a 773 service and parts book available in the manual thread, both can be quite helpful in figuring how things go and sourcing parts.

Thanks for the links, I'll see if there is anything there I don't already have re the 773. I should have mentioned before the first thing I do when purchasing a new toy or vehicle is to go find or buy the owners, service, and parts manuals which I already have for the 773 along with a new seat of course. Unfortunately I haven't found any details re to chain tension in the 773 service manual. My understanding is the Bobcat chains are one-piece (i.e. no master link) meaning to install requires pulling the axles and drive motors when there is an easier method using bulk #80 replacement chain 80H(?) with master link avoiding the additional teardown. There is Diamond chain (which may be owned by Timken now?) and which may or may not be made in China now which is rather pricey and then there is Tsubaki as well as 80HK from usarollerchain, not clear yet (to me) which is better etc for the price. The Diamond 80H chain would cost $1000 to replace all 4 chains i.e. 20' of chain plus the links when it looks like I could go the other route for 1/3 to 1/2 as much. I have no problem paying the extra IFF it's truly worth it.

 

[adsmith72]

Thanks for the links, I'll see if there is anything there I don't already have re the 773. I should have mentioned before the first thing I do when purchasing a new toy or vehicle is to go find or buy the owners, service, and parts manuals which I already have for the 773 along with a new seat of course. Unfortunately I haven't found any details re to chain tension in the 773 service manual. My understanding is the Bobcat chains are one-piece (i.e. no master link) meaning to install requires pulling the axles and drive motors when there is an easier method using bulk #80 replacement chain 80H(?) with master link avoiding the additional teardown. There is Diamond chain (which may be owned by Timken now?) and which may or may not be made in China now which is rather pricey and then there is Tsubaki as well as 80HK from usarollerchain, not clear yet (to me) which is better etc for the price. The Diamond 80H chain would cost $1000 to replace all 4 chains i.e. 20' of chain plus the links when it looks like I could go the other route for 1/3 to 1/2 as much. I have no problem paying the extra IFF it's truly worth it.

Here is a problem.. If i remember correctly you cant do one side front and back with a ten ft box.. Ask about custom length.. If i remember custom length cost more than just buying the boxes.. You have to over buy.. I think mine was something like HkK chain.. I bought mine from red boar chain. They were really fast and helpful... Make sure to get the master links that match the chain type and quality..I didn't get diamond.. To expensive.. I can look and see what I bought if you want me to.. OK for the important part.. A 773 is a narrow frame machine... Master links with cotter pins will hit the casting for the wheel motors on the front chains.. Here is my 2 cents.. Get the master link with cotter pins. put them in the chain with the pins facing inwards.. Its not easy to get them in facing inward, but trust me they will go.. Put one end of the master link in at the motor and the roll the chain forward and put the other end in the chain this is with the link on the upper run of the chain... Takes like 4 hands.. Put a small weld on the end of the master link pin.. Grind down for clearance and you will be good.. I spot weld all four links.. I know some people may disagree with the weld, but when you buy aftermarket chain you do not have much choice. It doesn't take much weld.. I have actually put the cotter pin in and then welded it before.. You are just try to hold the link face on.. I Look how small the cotter pin is.. It doesn't take much. Another thing..I can tell you from experience that those links hitting the casting will knock the cotter pins out.. Seems impossible, but I've seen it .. You can move the castings that the drive motors are in.. loosen the 5 bolts and get a big pry bar.. They have large bolt holes.. It doesn't take much movement to tighten the chains in one direction.. You may need to do this when you put new chains on.. Do not loosen the casting anymore than necessary. There is metal gasket on the outside of the chain case. Make sure you check the wheel bearings while you are doing all this..Hope this isn't to late to help. Good luck

 

[NoackBobcatGuy]

Here is a problem.. If i remember correctly you cant do one side front and back with a ten ft box.. Ask about custom length.. If i remember custom length cost more than just buying the boxes.. You have to over buy.. I think mine was something like HkK chain.. I bought mine from red boar chain. They were really fast and helpful... Make sure to get the master links that match the chain type and quality..I didn't get diamond.. To expensive.. I can look and see what I bought if you want me to.. OK for the important part.. A 773 is a narrow frame machine... Master links with cotter pins will hit the casting for the wheel motors on the front chains.. Here is my 2 cents.. Get the master link with cotter pins. put them in the chain with the pins facing inwards.. Its not easy to get them in facing inward, but trust me they will go.. Put one end of the master link in at the motor and the roll the chain forward and put the other end in the chain this is with the link on the upper run of the chain... Takes like 4 hands.. Put a small weld on the end of the master link pin.. Grind down for clearance and you will be good.. I spot weld all four links.. I know some people may disagree with the weld, but when you buy aftermarket chain you do not have much choice. It doesn't take much weld.. I have actually put the cotter pin in and then welded it before.. You are just try to hold the link face on.. I Look how small the cotter pin is.. It doesn't take much. Another thing..I can tell you from experience that those links hitting the casting will knock the cotter pins out.. Seems impossible, but I've seen it .. You can move the castings that the drive motors are in.. loosen the 5 bolts and get a big pry bar.. They have large bolt holes.. It doesn't take much movement to tighten the chains in one direction.. You may need to do this when you put new chains on.. Do not loosen the casting anymore than necessary. There is metal gasket on the outside of the chain case. Make sure you check the wheel bearings while you are doing all this..Hope this isn't to late to help. Good luck

Thanks for the advice, I appreciate it. I discovered my chains are not stretched after-all comparing left front chain with a new chain after I removed it from the machine. So I am only replacing the left front chain as I had to replace the left front sproket anyhow from where someone had previously welded the sproket to the hub and the weld has since cracked. I bought the chain direct from Bobcat as it's rugged Tsubaki HD chain and the price was right. My only problem at the moment is how to get the Tsubaki connecting link plate pressed onto the chain while on the machine as the pins are tapered and will require a weld to keep it on once I get it pressed on. I cannot seem to locate a suitable tool to press a #80H sideplate on while on the machine and I would like to avoid the #80H cotter pin master pin route if I can. And yes re the bulk chain for 773, two 10' boxes isn't enough as the fronts are 62" long and the rears are 68" long, hence the direct from Bobcat route. Separately, so what lubricates the axle and drive-motor inner bearings? Is it the oil from the chain case? I don't think it is as the oil level in the chain case is not high enough to reach as far as I can tell. Presumably the outer axle bearings are grease lubed? I have not pulled the axles nor the drive motors and wasn't planning to unless this is an absolute must-do when purchasing an older machine like this.

 

[adsmith72]

Thanks for the advice, I appreciate it. I discovered my chains are not stretched after-all comparing left front chain with a new chain after I removed it from the machine. So I am only replacing the left front chain as I had to replace the left front sproket anyhow from where someone had previously welded the sproket to the hub and the weld has since cracked. I bought the chain direct from Bobcat as it's rugged Tsubaki HD chain and the price was right. My only problem at the moment is how to get the Tsubaki connecting link plate pressed onto the chain while on the machine as the pins are tapered and will require a weld to keep it on once I get it pressed on. I cannot seem to locate a suitable tool to press a #80H sideplate on while on the machine and I would like to avoid the #80H cotter pin master pin route if I can. And yes re the bulk chain for 773, two 10' boxes isn't enough as the fronts are 62" long and the rears are 68" long, hence the direct from Bobcat route. Separately, so what lubricates the axle and drive-motor inner bearings? Is it the oil from the chain case? I don't think it is as the oil level in the chain case is not high enough to reach as far as I can tell. Presumably the outer axle bearings are grease lubed? I have not pulled the axles nor the drive motors and wasn't planning to unless this is an absolute must-do when purchasing an older machine like this.

If you haven't bought the chain yet I would consider trying to move the motor carrier casting to tighten the front chain.. Just a thought.... The motors are lubed by the hyd fluid and the casting that hold the motor has bearings that are lubed by the chain case oil.. This is the shaft with the small sprocket on it..The wheel bearings are lubed by the chain-case oil.. I know it seams low, but imagine your truck axles .. They are the same thing.. I fill my chain case from the top cover plate, so usually over fill a tiny bit.. Dont fill up past the axle shaft bottoms. Make sure you check your wheel bearings.. Make sure to check with the wheel on the hub.. You need all the leverage you can get to see how loose they are.. Now is the time to fix them. It is a real job, but now that you have all the hyd lines off fix them if they are bad.. Also check the motor carrier bearings.. That is the sprocket that the chains go on.. See if the have a lot of in and out play.. They a not usually bad.. Wheel bearings an often overlooked part of buying a skid steer.. They are very expensive to have a dealer fix, and most people cant do them themselves.. Also they dont check the bobtach plate good enough.. Bobtach plates are easy to fix if they are fixed before permanent damages is done.. Very expensive to fix after that..Dont run your bobtach until the bushings are gone and you cant rebuild it.. Hope that make sense..

 

[NoackBobcatGuy]

If you haven't bought the chain yet I would consider trying to move the motor carrier casting to tighten the front chain.. Just a thought.... The motors are lubed by the hyd fluid and the casting that hold the motor has bearings that are lubed by the chain case oil.. This is the shaft with the small sprocket on it..The wheel bearings are lubed by the chain-case oil.. I know it seams low, but imagine your truck axles .. They are the same thing.. I fill my chain case from the top cover plate, so usually over fill a tiny bit.. Dont fill up past the axle shaft bottoms. Make sure you check your wheel bearings.. Make sure to check with the wheel on the hub.. You need all the leverage you can get to see how loose they are.. Now is the time to fix them. It is a real job, but now that you have all the hyd lines off fix them if they are bad.. Also check the motor carrier bearings.. That is the sprocket that the chains go on.. See if the have a lot of in and out play.. They a not usually bad.. Wheel bearings an often overlooked part of buying a skid steer.. They are very expensive to have a dealer fix, and most people cant do them themselves.. Also they dont check the bobtach plate good enough.. Bobtach plates are easy to fix if they are fixed before permanent damages is done.. Very expensive to fix after that..Dont run your bobtach until the bushings are gone and you cant rebuild it.. Hope that make sense..

I've already replaced the front left sprocket and chain, well the chain is on the machine with the connecting link in-place but still need to figure out how to press the side onto the connecting link. Re bearings, yes that makes sense as there is no seal between the gear case and the inner bearings. I already did the jack-up-one axle at a time to see if there is any play in the bearings, first thing I did actually, all 4 seem to be in good shape amazingly enough. I do still need to check the motor carrier bearings which I'll do tonight. Heh re the bobtach funny you mention that, yeah the bucket that's on it looks to have been on it since forever. I have been putting the ole PB blaster to the pins regularly, but they aren't budging unfortunately. Once I get the chain case back together I'll bring the boom down where I can maybe beat on the wedges from the bottom I dunno if that's a good idea or not, not sure what else to try to get those pins up out of the holes. I can try to put the heat to it but it's a rather large surface area doubtful that'll work. I need to do some more reading on that to see if anyone has any great ideas how-to do that. I haven't read-up on it yet as my time has been consumed dealing with this bad sproket and replacing the chain.

 

[adsmith72]

I've already replaced the front left sprocket and chain, well the chain is on the machine with the connecting link in-place but still need to figure out how to press the side onto the connecting link. Re bearings, yes that makes sense as there is no seal between the gear case and the inner bearings. I already did the jack-up-one axle at a time to see if there is any play in the bearings, first thing I did actually, all 4 seem to be in good shape amazingly enough. I do still need to check the motor carrier bearings which I'll do tonight. Heh re the bobtach funny you mention that, yeah the bucket that's on it looks to have been on it since forever. I have been putting the ole PB blaster to the pins regularly, but they aren't budging unfortunately. Once I get the chain case back together I'll bring the boom down where I can maybe beat on the wedges from the bottom I dunno if that's a good idea or not, not sure what else to try to get those pins up out of the holes. I can try to put the heat to it but it's a rather large surface area doubtful that'll work. I need to do some more reading on that to see if anyone has any great ideas how-to do that. I haven't read-up on it yet as my time has been consumed dealing with this bad sproket and replacing the chain.

Check the lower pins and bushings on the bobtach. If you ruin the bushing pockets, you are in trouble.. No good way to fix them.. There is value in keeping those fixed up. Go to allskidsteers and get a kit..

 

[craigb93]

Thanks for the advice, I appreciate it. I discovered my chains are not stretched after-all comparing left front chain with a new chain after I removed it from the machine. So I am only replacing the left front chain as I had to replace the left front sproket anyhow from where someone had previously welded the sproket to the hub and the weld has since cracked. I bought the chain direct from Bobcat as it's rugged Tsubaki HD chain and the price was right. My only problem at the moment is how to get the Tsubaki connecting link plate pressed onto the chain while on the machine as the pins are tapered and will require a weld to keep it on once I get it pressed on. I cannot seem to locate a suitable tool to press a #80H sideplate on while on the machine and I would like to avoid the #80H cotter pin master pin route if I can. And yes re the bulk chain for 773, two 10' boxes isn't enough as the fronts are 62" long and the rears are 68" long, hence the direct from Bobcat route. Separately, so what lubricates the axle and drive-motor inner bearings? Is it the oil from the chain case? I don't think it is as the oil level in the chain case is not high enough to reach as far as I can tell. Presumably the outer axle bearings are grease lubed? I have not pulled the axles nor the drive motors and wasn't planning to unless this is an absolute must-do when purchasing an older machine like this.

Don't know exactly how much room you have to work in but you can try using a pneumatic hammer with a made up rivet set tool and a block of steel (or hammer if there is room) to back it up. All chain pins are just long rivets that are expanded into the side plate. You can make the rivet set from a chisel or any special purpose tool with enough straight round length. Cut off the chisel point and drill a hole the tip to drive the plate on. Heat and bend it if no clearance for the hammer in a straight line. If you want to use the cotter pin link just make the tool a bit convex on the end and drive it up to expand the pin into the plate. I worked in the aircraft industry while going to school and made several custom rivet sets to suit crowded air-frame work. -Dick