I have a Cat 312C serial CBA04192 the right side track started to show signs of failure would intermittently jam up. Now it is locked and won't go either direction the oil goes over relief either direction. I swapped the lines at the control valve from left to right track and problem stayed on the right track so eliminated from control valve back (left track always works fine even with lines swapped). I then took apart the final drive and with the gears removed looking at the motor shaft it crunches back and forth a 1/4 inch or so in either direction. So I am pretty certain the motor is the issue, the final drive gears and bearings look perfect oil was clean. I don't see where cat lists the motor for this unit I do see part 507-1117 for the drive and motor group at $30,000. Is it common practice to replace these as a whole? Parts seem to be available for the motor. Looking for some insight into what my options are or if anyone has rebuilt these motors. Thank you
Has anyone ever change the final drive gear case oil in those machine?
Not sure the history of the machine the oil had no metal filings and was clean. The gear oil should be separate from the motor internals no?
Yes gear oil is separate from hydraulic side. How much do you use the machine? I’ve repaired quite a few drive motors. If the case is ok then you could replace damaged parts, assuming they’re available. I would be more concerned about contamination at this point. Pop it off and open it up, can’t hurt it any worse than it already is. I’m not sure how stout the brake springs are in that particular motor. Might see if somebody can post disassembly procedure to see what Cat says in regard to that.
Have you cut open the case drain filter yet.? If not I suggest that you do that first. The amount of metal in the filter media will give you an idea of how catastrophic the motor failure is.
I do........ #2 in the illustration below for machines above CBA4121 which includes yours. Latest Part Number for the motor is 302-9179. Individual spare parts are available. FYI the 507-1117 Final Drive is a different design that can be retrofitted as a complete unit to a number of excavator models including yours BUT it has to be installed as a PAIR of new final drives along with a new centre swivel assembly and a load of hydraulic hoses.
Interesting I couldn't find that on SIS thanks. When I add 302-9179 to cart on cat parts site it says its been replaced by 507-1117.
That's because the complete motor assembly has been discontinued. Repair parts for the 302-9179 still appear to be available. If you want a complete 302-9179 then you have to buy a final drive 507-1117. To fit a 507-1117 you have to buy TWO of them, PLUS a centre swivel PLUS a shed-load of hoses. See attached. Either cross your fingers that your motor is repairable or IMHO you will likely be looking for an aftermarket replacement.
Ok thanks for that information
Back to Post #5. You really need to cut open the case drain filter (#10 on the back side of the hydraulic tank) first. What you find in there is pretty much going to determine whether or not it's even worth opening up the travel motor.