743 chain case

[Bied10]

Good afternoon. New member here. I own a 743 that has served me well for a long time. The right rear wheel free spins- I am assuming a chain has broken since it spins effortlessly and doesn't make any noise when you spin it. I read every thread there is on this repair, and Tazza stated that he has dropped the chain case out the bottom. I am very interested in this approach, because I have ZERO leaks on this machine. I think if I can drop the case to replace things without opening the hydro system (that is 30 years old) I will possibly save a lot of headaches. My question is this. I see the bolts holding the case near the axles (approximately 20) and the 2 blots that hold the pump to the case. I feel like my next step would be the linkage for the foot pedals. What I don't know is the location of any other fastening points that I can't see. The repair manual is great, but not set up like a car repair manual that goes step by step. Also, how heavy will the machine be without the chain case and tires? I am guessing the case is around 1000# Has anyone done this and is it going to be a "simple" as I think or am I crazy. Any advice would be helpful. Thank you Mike Biedenharn Hilliard Ohio.

 

[Bied10]

I guess I forgot to mention that I would pull the drive motors from the reduction gears. (can this be done without disconnecting the lines?) Thanks Mike

 

[Tazza]

I guess I forgot to mention that I would pull the drive motors from the reduction gears. (can this be done without disconnecting the lines?) Thanks Mike

The only one you have missed from that list is the lift linkage, there is a bar that runs under the pump to the control valve. You will need to disconnect the 3 hoses from the drive motors.
You will then need to jack the main frame up and just roll the chain case out.
I haven't done it before, i have stripped a machine down to nothing, but never just pulled the frame off, yet there was a post in the mid 2000s that a guy did just that with success.
The hardest part will be lifting the frame high enough to roll the chain case out under it safely. The chassis with lift arms and motor in will be heavy, stay safe doing it.

 

[Bied10]

The only one you have missed from that list is the lift linkage, there is a bar that runs under the pump to the control valve. You will need to disconnect the 3 hoses from the drive motors.
You will then need to jack the main frame up and just roll the chain case out.
I haven't done it before, i have stripped a machine down to nothing, but never just pulled the frame off, yet there was a post in the mid 2000s that a guy did just that with success.
The hardest part will be lifting the frame high enough to roll the chain case out under it safely. The chassis with lift arms and motor in will be heavy, stay safe doing it.

Merry Christmas. Well 2 months have passed and I am ready to start this project. I am taking pictures so I can post the results if it works. I have all but 3 bolts out of the case. the 3 under the spool valve are giving me trouble. I made a 5' long open end wrench and was able to get to the first two. the next one is being stubborn. I ordered a snake eye camera so I can see if it is pinned by the spool valve, or if I just have too much mud pack blocking my wrench. (I may have to put a little angle on the 5' wrench- that is what the camera will tell me) I also need to go buy 2 bottle jacks if Santa doesn't bring them to me tomorrow. Hopefully it will all go smooth and I will be asking questions about bearings, torque multipliers and chain slack soon! Lets hope the 40 degree weather holds out for a bit. Updates soon. Mike

 

[Bied10]

Merry Christmas. Well 2 months have passed and I am ready to start this project. I am taking pictures so I can post the results if it works. I have all but 3 bolts out of the case. the 3 under the spool valve are giving me trouble. I made a 5' long open end wrench and was able to get to the first two. the next one is being stubborn. I ordered a snake eye camera so I can see if it is pinned by the spool valve, or if I just have too much mud pack blocking my wrench. (I may have to put a little angle on the 5' wrench- that is what the camera will tell me) I also need to go buy 2 bottle jacks if Santa doesn't bring them to me tomorrow. Hopefully it will all go smooth and I will be asking questions about bearings, torque multipliers and chain slack soon! Lets hope the 40 degree weather holds out for a bit. Updates soon. Mike

Success. At least the removal part. We raised the body and rolled the chain case out in a little under 90 minutes.

 

[Bied10]

Success. At least the removal part. We raised the body and rolled the chain case out in a little under 90 minutes.

Here is a picture of the final result. I removed all the bolts, disconnected the linkage for the left pedal and ended up having to disconnect the right pedal also.

We started jacking up on the beam and cribbed as we went (slow and steady)
Picture of the rear.

early success lifting

Check for any obstructions as you lift. The linkage that bolts to the top of the chain case was in the way a lot. once we were almost clear, we were able to get a wrench on the pivot bolt and remove it.

Here is the lifting rig close up.

I also had to grind an open end wrench (3/4") real skinny to hold the bolts that hold the hydro pump to the case because they were spinning. I will post pictures of the 5' wrench I welded to get to the chain case bolts in the rear next time I am in the barn.

I am still worried about reinstalling the 3 bolts that are under the spool valve. there is 30 years of mud/oil packed around the bolts that I have to dig out.

 

[bobbie-g]

Here is a picture of the final result. I removed all the bolts, disconnected the linkage for the left pedal and ended up having to disconnect the right pedal also.

We started jacking up on the beam and cribbed as we went (slow and steady)
Picture of the rear.



early success lifting



Check for any obstructions as you lift. The linkage that bolts to the top of the chain case was in the way a lot. once we were almost clear, we were able to get a wrench on the pivot bolt and remove it.

Here is the lifting rig close up.



I also had to grind an open end wrench (3/4") real skinny to hold the bolts that hold the hydro pump to the case because they were spinning. I will post pictures of the 5' wrench I welded to get to the chain case bolts in the rear next time I am in the barn.

I am still worried about reinstalling the 3 bolts that are under the spool valve. there is 30 years of mud/oil packed around the bolts that I have to dig out.

Wow! I love that workmanship! Great job! ---Bobbie-G

 

[Tazza]

Wow! I love that workmanship! Great job! ---Bobbie-G

Great job, dropping the chain case like this makes working on it so much easier.