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Thread: Cat #12 grader tranny noise.

  1. #1
    Join Date
    Feb 2014
    Location
    British columbia
    Posts
    16

    Default Cat #12 grader tranny noise.

    Hey all, I've got a noise coming from the transmission of my 1952 #12 grader. It only occurs in first and second gear, and sounds like a consistent knocking or clunking. I noticed it awhile back, but kept using it as I didn't want to tear into the transmission. It is getting stronger now so I guess I need to address it. I am wondering if anyone has ever experienced this or might know what it is--I am open to any and all suggestions I am holding out a slim hope that it may only be something out of adjustment, and not a major transmission problem. Thanks all for your help.

    Taylor

  2. #2
    Join Date
    Nov 2006
    Location
    Faunsdale, AL USA
    Posts
    3,536

    Default

    Ha!

    Ours has a knock in high gear when you get up to speed........I don't go fast much anyway. We were told that the local old CAT mechanic had welded up some gears in it long before we got it. My question is how would anyone have ever broken high?

    Hope I never get to find out what it really is!
    D2-5J's, D6-9U's, D318 and D333 power units, 12E-99E grader, 922B & 944A wheel loaders, D330C generator set, DW20 water tanker and a bunch of Jersey cows to take care of in my spare time

  3. #3
    Join Date
    Jan 2007
    Location
    long island NY, Hancock Ma
    Posts
    2,059

    Default

    I had a 5 speed spicer tranny that had a consistent clunking---found that a gear tooth had broken off---fished it out from a plate we removed from the side of the housing
    Cat 941B, Cat D2 4U, Cat D3B, Cat D4 7U, Cat D6 9U

  4. #4
    Join Date
    Apr 2012
    Location
    Farmington, Ca.
    Posts
    476

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    Takes me back 4 decades but we had an 8T grader that had a shaft bearing failure on the front bearing plate more than once. This particular bearing was not pressure fed it was oiled by oil that ran down the plate from above. I remember drilling the oil hole bigger and fabbing a oil trap to guide oil to the bearing. That's all I remember, I had the trans out twice which is not a small job. Good luck
    1962 D4C,1966 D4D

  5. #5
    Join Date
    Feb 2014
    Location
    British columbia
    Posts
    16

    Default

    Thanks for the input! That kind of lines up with what I was thinking--either a broken tooth or bad bearing/bushing. I don't suppose that I can access that gear with the tranny still in the machine?

  6. #6
    Join Date
    Nov 2006
    Location
    Minnesota
    Posts
    340

    Default

    Taylor, that transmission is completely repairable in the machine. I have done one twice. Sit on a creeper and roll under the cab looking at the front of the trans. You want to be at a comfortable working height. I am taller so I run the rear wheels onto 2x6s. Then start taking it apart from the front in. If you are fairly mechanical it isn't tough. Some of the case halves are pretty heavy. A service book can help you know what you are looking at. As of 5 years ago all the bearings, seals and gaskets were available from Cat except the big case gasket. I used gasket maker on that. Gears and bearing cages/sleeves were available used. The one shaft that was needed the second time due to a bearing failing that looked good was available NOS. It is do able. Someone to help lift parts and pass you tools will be a great help.

  7. #7
    Join Date
    Feb 2014
    Location
    British columbia
    Posts
    16

    Default

    Kracked1, thanks for that!--you give me hope I was about ready to just run it till it dies.

  8. #8
    Join Date
    Jul 2016
    Location
    Lancaster CA
    Posts
    362

    Default

    Quote Originally Posted by kracked1 View Post
    Taylor, that transmission is completely repairable in the machine. I have done one twice. Sit on a creeper and roll under the cab looking at the front of the trans. You want to be at a comfortable working height. I am taller so I run the rear wheels onto 2x6s. Then start taking it apart from the front in. If you are fairly mechanical it isn't tough. Some of the case halves are pretty heavy. A service book can help you know what you are looking at. As of 5 years ago all the bearings, seals and gaskets were available from Cat except the big case gasket. I used gasket maker on that. Gears and bearing cages/sleeves were available used. The one shaft that was needed the second time due to a bearing failing that looked good was available NOS. It is do able. Someone to help lift parts and pass you tools will be a great help.
    Great to know! Thanks
    Cat 12 grader, 8T running and restoring, Cat 12 grader 9K3585. parts machine, Adams leaning wheel Pull grader Mod # 28,

  9. #9
    Join Date
    Nov 2006
    Location
    Minnesota
    Posts
    340

    Default

    Your welcome.

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