Major Noise in T-18 Transmission - 79 CJ7

Discussion in 'General Tech' started by chris jones, Jul 12, 2020.

  1. chris jones

    chris jones Active Member

    Joined:
    Oct 10, 2014
    Location:
    huntersville
    I took my son and a couple of his friends to teach them how to drive a straight drive in my 79 CJ7. Obviously there was a lot of stalling and jerky starts, but they weren't too bad on it. Unfortunately, now I've got an awful noise and vibration. The vibration happens in all gears and I feel like it you really feel it when you let out the clutch. There is a metal on metal sounding vibration that is significant when you start to get around 30-45 mph. This Jeep has a 304 V8, T-18 transmission mated to a Dana 20 transfer case. You can still hit all gears and shift through the transfer case. I have a video where you can see the excessive vibration and hear the noise. Just need to figure out how to upload...

    Any clue?
     
  2. Jody Treadway

    Jody Treadway Croc wearing fool Moderator

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    Mar 20, 2005
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    Hendersonville, NC
    Any chance a motor mount or tranny mount is now broken?
     
    Last edited: Jul 13, 2020
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  3. Tim C

    Tim C Wizard

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    Jan 22, 2007
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    Fayetteville
    Does the noise and vibrating happen in trans neutral with or without clutch pressed? How about t case neutral and trans in gear?

    Save video to youtube if you have to and link it here. I'm not exactly sure how to embed video myself.
     
  4. McCracken

    McCracken Logan Can't See This

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    Any binding in the clutch linkage? That could be a sign of a motor mount that's let go.
     
  5. chris jones

    chris jones Active Member

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    So the mounts look good. It looks like I may be missing the bolt to the bell housing but the 3 that are there are solid. Everything seems fine with the clutch linkage and there are no problems with pushing or releasing the clutch pedal. I drove it again this morning and feel vibration at the top of the clutch pedal and at about 40 mph you hear the vibration in 3rd or 4th. More pronounced when under a load.

    Here's a video. There's a lot of general noise but you can hear the sound.

     
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  6. chris jones

    chris jones Active Member

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    You hear the noise about 15 seconds in. The general vibration you see is more than it was a week ago. I also feel like it may be misfiring.
     
  7. McCracken

    McCracken Logan Can't See This

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    you would think you'd feel that vibration without having to drive it if it's an engine issue. Just rev it up and see if it's there.
     
  8. WARRIORWELDING

    WARRIORWELDING Owner opperator Of WarriorWelding LLC.

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    Chillin, Hwy 64 Mocksville NC
    Have you checked any of the u-joints?
    Spit balling, could the flywheel be out of balance? I figure it's one piece maybe externally ballanced? I had a two piece in a Power Stroke go the pieces, but they were known for it.
     
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  9. shelby27604

    shelby27604 Well-Known Member

    Joined:
    Jun 6, 2013
    Location:
    Raleigh
    How old is the clutch? My money is on a broken clutch dampener spring.
    Revving the engine while doing the following:

    -Trans. In neutral, clutch pedal out....if you can duplicate the noise it might be in the clutch or engine.
    -Transfer case in neutral, running through the transmission gear, if you can duplicate the noise it is in the transmission or the engine. (I am not sure how informative this test would be with a broken disc spring, as if it is lodged somewhere, it might still contribute to unbalance)
    -Not moving, transmission in gear, foot on the clutch if you can duplicate the noise/vibration it is in the engine or flywheel.

    Obviously you do all 3 and by process of elimination you can find which is your most likely issue.

    someone will be along shortly to correct my oversights.
     
    Last edited: Jul 13, 2020
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  10. chris jones

    chris jones Active Member

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    I can start to hear it in scenario 2. Feel like it’s in the clutch/flywheel/pp realm. U joints aren’t bad. Rear has a little play but same as when I got it.
     
  11. shelby27604

    shelby27604 Well-Known Member

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    Location:
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    In scenario 2, does the noise/vibration change with different gears?

    I should mention in all of these scenarios I would have a foot on the brake or the parking brake set.
     
  12. chris jones

    chris jones Active Member

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    You can feel vibration in low gears but the noise doesn’t happen until you get to about 45 miles an hour in third and fourth. When I was stopped I could barely get the noise to happen in third and fourth. At low gear high occasionally hear a ticking noise or rattle. It honestly seems like it’s got to be something with the pressure plate clutch fly wheel. There is no issue with the clutch pedal it’s self However.

    And regarding your last statement, I am a professionally trained monkey. Parking brake was set the entire time.
     
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  13. Tim C

    Tim C Wizard

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    Fayetteville
    Clutch pressure plate or flywheel will makenoise with trans in neutral. If it only does it with the trans in gear and t case in neutral it's in the transmission.
     
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  14. rodney eppes

    rodney eppes Well-Known Member

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    Location:
    Mt.Holly NC 28120
    I too was wondering if the clutch got damaged, or lost some material? but if you lost any of the material, i think you'd feel it when engaging. It'd be grabbing, jerking or bouncing the pedal. Regardless of the problem, someone will have to disassemble the clutch & tranny, to find what's wrong. Hope you got a cool garage!
     
  15. shelby27604

    shelby27604 Well-Known Member

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    Sounds like a high rpm vibration and a low rpm ticking/rattle.....which sounds like a broken dampener spring, maybe a piece got into a void on the pressure plate and that is what is causing the unbalance vibration.
     
  16. chris jones

    chris jones Active Member

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    So I took it by a mechanic to try and get it back on the road ASAP. Apparently whatever noise I thought I heard when I was testing it in the driveway wasn’t it.

    Apparently, the rear axle tubes spun casing the rear end and drive shaft to not hit right. They twisted them back and welded them in position. No noise at all. Drives like a champ.

    I appreciate everyone’s responses here. You guys were great.
     
  17. rodney eppes

    rodney eppes Well-Known Member

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    Wow! Them boys must have been harder on it than you thought! Pulling some Wheelies!:burnout:
     
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  18. shelby27604

    shelby27604 Well-Known Member

    Joined:
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    Location:
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    Crazy they managed that!

    A tip, when teaching people to drive a stick shift, I try to start with putting the vehicle in 1st gear and starting / stopping using only the clutch (no gas). I find most learning drivers struggle most with identifying the feel of the clutch engagement, and the noise of the revving engine (something they are not consciously aware of in an automatic), only exacerbates the situation.

    Leave the hubs unlocked and toss it into 4-lo if you want to make it really easy.
     
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