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973 drive motor

Discussion in 'Track Loaders' started by gwhammy, Jun 19, 2021.

  1. gwhammy

    gwhammy Senior Member

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    One of the drive motors on my 973 has a slow leak from the motor into the final drive compartment. Takes 30 to 40 hours to leak around 5 gallons. Cat doesn't support hard parts for these motors anymore. I found a used one and plan on trying to fix this one for a spare. Are the bearings and seals available? It shows no metal and pulls strong. It's a 86g serial number.
     
  2. Tones

    Tones Senior Member

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    The bearings should have numbers stamped in the outer race. They represent all the dimensions of that bearing so give them to your local bearing shop and see what they can find. It pretty much for seals, give the the inner and outer diameter's, the thickness. The seal should be a viton lip
     
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  3. Nige

    Nige Senior Member

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    The answer is - "it's complicated".

    There are 37 hits on drive motors for an 86G prefix machine and there are at least a dozen different Part Numbers. Some Part Numbers have "Type 1" & "Type 2" motors for the same P/N. I haven't devled into the differences etween the two types.
    If the motor that you propose to repair is the original from the machine then either the Part Number off the tag on the motor or a full Serial Number is going to be required. TBH I think both together would give the best chance of success.
     
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  4. gwhammy

    gwhammy Senior Member

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    Thanks, it seems nothing is simple in my world. I've got a real good parts guy at the local cat dealer. I don't know if it's the original or not, it shows signs of someone being into it before.
     
  5. Nige

    Nige Senior Member

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    In that case I would suggest that the best way would be get the P/N from the tag on the motor.
    Failing that it would be a case of pull the motor apart and see if anything significant internally has a Part Number marked on it and try to work backwards to the motor Part Number that way.

    A quick look reveals a slew of Service Magazine articles and Special Instructions regarding the motor. Not surprising I suppose if the Part Number changed so many times.

    It's worth mentioning that there was a Steel Mill (slag) arrangement for the 973 therefore some of the motors may be specific to that Arrgt. This would narrow the field down somewhat.
     
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  6. gwhammy

    gwhammy Senior Member

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    Thanks, I appreciate the info. One thing about it the motor is useless the way it is so it's no loss tearing it apart.
     
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  7. Cmark

    Cmark Senior Member

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    Those motors are a nice heavy built unit with big old taper roller main bearings. The seal in in a removable carrier which bolts to the case and replacing it is a matter of minutes once the motor is out. If the machine works OK then the bearings should be good.

    By the way, are you sure it's the motor? A leaking parking brake will fill the final drive with transmission oil as well.
     
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  8. gwhammy

    gwhammy Senior Member

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    I thought about that also but don't know enough about the system. I'm guessing there's no way of knowing which one is leaking without tearing it down farther.
     
  9. Nige

    Nige Senior Member

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    Pressurize the park brake circuit with a portapower.?
     
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  10. gwhammy

    gwhammy Senior Member

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    Here's what we come up with today. The o ring on the drive shaft going into the motor is not cut. Looks like we are going to reinstall the motor and put a pressure gauge on the case drain line to see how much bypass it has.

    The brakes use around 200 psi to disengage them. Going to take the line off and block it and see if the brakes hold or not. We think maybe they have been leaking and not completely taking the brakes off which is the reason for the glitter look in the oil.

    A logger friend of mine said he had a tree processor blow a seal on a hydro-stat. It dumped all the oil immediately.

    I'm pretty sure it's narrowed down to the brakes now but time will tell.
     
  11. Cmark

    Cmark Senior Member

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    As Nige said, test the brake system with pressure. It's pretty easy to rig up with a gauge, valve and shop air. Pressurise the system, close the valve and see if it leaks down.

    The way to test for excess internal motor leakage is to check the case pressure. There should be a test point there already. You should have no more than about 2 psi. Check at high idle stationary and also high idle full travel speed.
     
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  12. Cat977

    Cat977 Senior Member

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    Good simple tests! Gotta love'em! Cmark's test I think doesn't actually call for the brakes to release, it just looks for leaking. As for o-rings they can look pretty good but still wear/distortion/hardening can still have them leak. New o-ring has got to be cheap insurance. Glitter in the oil anywhere should be tracked down.
     
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  13. gwhammy

    gwhammy Senior Member

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    These old mechanical machines are a lot easier for the old timers I hang with. Time will tell but I'm feeling better about it with more info. Thanks
     
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  14. gwhammy

    gwhammy Senior Member

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    I got sent the wrong direction by a couple mechanics. The brakes are toast, evidently it's been leaking from the apply pistons and not disengaging the brakes completely. Motor is fine. Hopefully it didn't tear up any hard parts when we finally get it off this coming week. If I had done a little more digging it would have been easy to diagnose but I trusted the advice I had gotten when we first found extra oil in the finals.
     
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