Hey all, I’m new to this forum this is my first post. I have a 2001 938G Cat Loader serial starting 4YS0. Did a service on it recently which included changing diff oil and replacing a leaked out brake accumulator. Since the servicing the front end seems to be binding up on slow turning. The front wheels shake and hop a little. Was fine before the service which has me boggled. Is it possible to overfill the front diff/axle and cause problems? Also, when I bought the accumulator there was some confusion in the cat tech documents at the cat shop for the nitrogen charge to put in it but the technician ended up going with 1000psi. Sound right? Could an over charged accumulator be causing a brake issue? The machine is not constantly binding. Seems to be happening while starting a sharp turn or straightening out of a sharp turn at very low speed. Any advice greatly appreciated
That machine should probably have a friction modifier added to the diff oil to keep it from chattering when you apply the brakes. Are you applying the brakes also when it happens. Friction modifier i think is 1u1998 from Cat.
Not applying the brakes when it happens.
Hate to say it, but that is the classic symptoms of the spider gears failing. Hopefully someone here knows of another less expensive failure.
1000psi @ 70 DegF ambient temp is the correct precharge pressure for the brake accumulator. For every 10 DegF above 70F ambient add 20psi to the precharge pressure, for every 10 degF below 70, reduce the precharge pressure by 20psi. When the axle oil was drained what did the magnetic plugs on the front axle look like..? Any major signs of metal..? What type & grade of oil did you put in it..?
No sign of significant wear when we changed the oil. Put back the spec oil. Can’t remember the exact name on it. Maybe just great coincidence that it started right after the servicing. Going to take a look at the plugs tmrw see if it’s making any metal. I have very little experience on maintenance side of things. Any suggestions on troubleshooting and appropriate tear down?