1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

NV4500 clunk

Discussion in 'Manual Transmission & Clutch' started by Frankenchevy, Jan 7, 2021.

  1. Frankenchevy

    Frankenchevy Lying Dog-Faced Pony Soldier

    Posts:
    4,757
    Likes Received:
    4,969
    Joined:
    Jan 3, 2018
    Location:
    USA
    First Name:
    Jeremy
    Truck Year:
    Square
    Truck Model:
    CUCV
    Engine Size:
    Small
    Hey. All new components including NV4500 professionally rebuilt. When the drivetrain transitions from being under load to unloaded (whether just letting off the gas or pressing the clutch) I get a clunking noise. In this video I’m driving around my driveway circle and periodically letting off the gas. That’s when the audible clunk is heard. Everything is tight and no noises like this came from anywhere with my TH400. Seems like I’ll be pulling this transmission and waiting for another...

    <iframe class="rumble" width="640" height="360" src="https://rumble.com/embed/v9wv1h/?pub=axwcn" frameborder="0" allowfullscreen></iframe>
     
  2. DoubleDingo

    DoubleDingo Drain The Swamp, Completely

    Posts:
    6,174
    Likes Received:
    5,323
    Joined:
    Jul 3, 2012
    Location:
    Right where I am
    First Name:
    Bagoomba
    Truck Year:
    1981, 1965
    Truck Model:
    81-C20 Silverado Camper Special-TH400-4.10s; 65-C20 with 4:57 gears and Borg Warner Overdrive
    Engine Size:
    Carb'ed Vortec 350; 1972 L48 350
    You do have a direct connection now. If you had a gopro I bet you could find the cause of that. I have a feeling it is just a little slop in the gears. Other than that sound, it sounds like a normal manual transmission setup.
     
  3. Dutch Rutter

    Dutch Rutter Full Access Member

    Age:
    31
    Posts:
    865
    Likes Received:
    813
    Joined:
    Aug 13, 2013
    Location:
    Independence, Or
    First Name:
    Joshua
    Truck Year:
    1984
    Truck Model:
    K20
    Engine Size:
    5.7
    Is it possible that there isn't enough clearance between the cab cut out and the top of the trans? Would probably make a different noise then an internal trans knock though.

    Dingo is right too. You dont have the auto cushion anymore to soak up some of the harshness, if a u joint was on the verge with the auto it'll be louder with the manual.
     
    DoubleDingo likes this.
  4. DoubleDingo

    DoubleDingo Drain The Swamp, Completely

    Posts:
    6,174
    Likes Received:
    5,323
    Joined:
    Jul 3, 2012
    Location:
    Right where I am
    First Name:
    Bagoomba
    Truck Year:
    1981, 1965
    Truck Model:
    81-C20 Silverado Camper Special-TH400-4.10s; 65-C20 with 4:57 gears and Borg Warner Overdrive
    Engine Size:
    Carb'ed Vortec 350; 1972 L48 350
    Just watched it again, hard to tell. You're a fine mechanic but did you make sure all the mounts were snuggled up? Is something now hitting the frame or body with a flop?
     
  5. DoubleDingo

    DoubleDingo Drain The Swamp, Completely

    Posts:
    6,174
    Likes Received:
    5,323
    Joined:
    Jul 3, 2012
    Location:
    Right where I am
    First Name:
    Bagoomba
    Truck Year:
    1981, 1965
    Truck Model:
    81-C20 Silverado Camper Special-TH400-4.10s; 65-C20 with 4:57 gears and Borg Warner Overdrive
    Engine Size:
    Carb'ed Vortec 350; 1972 L48 350
    That's why I mentioned gopro. It's amazing what you see with one of those mounted under a vehicle.
     
    Dutch Rutter likes this.
  6. Frankenchevy

    Frankenchevy Lying Dog-Faced Pony Soldier

    Posts:
    4,757
    Likes Received:
    4,969
    Joined:
    Jan 3, 2018
    Location:
    USA
    First Name:
    Jeremy
    Truck Year:
    Square
    Truck Model:
    CUCV
    Engine Size:
    Small


    I’ve had several vehicles with a manual trans and it sounds a bit unnerving.
    I looked at that even though it didn’t sound like contact with the floor and I don’t see any witness marks.


    all mounts are brand new and snug...


    I talked to advance Adapters and they think it sounds like excess backlash. Pretty sure that’s what they said, but that’s just from my description. They didn’t see the video.
     
  7. Frankenchevy

    Frankenchevy Lying Dog-Faced Pony Soldier

    Posts:
    4,757
    Likes Received:
    4,969
    Joined:
    Jan 3, 2018
    Location:
    USA
    First Name:
    Jeremy
    Truck Year:
    Square
    Truck Model:
    CUCV
    Engine Size:
    Small
    I’ll check the floor again, but it sounds internal. How much clearance between the shift tower and the floor should there be? 1/4”?

    I should mention that when I filled the trans, it leaked from not PTO covers, so I had to drain and seal it back up. Maybe the rebuilder was having an off day.

    I don’t have a go pro, wish I did sometimes.
     
  8. DoubleDingo

    DoubleDingo Drain The Swamp, Completely

    Posts:
    6,174
    Likes Received:
    5,323
    Joined:
    Jul 3, 2012
    Location:
    Right where I am
    First Name:
    Bagoomba
    Truck Year:
    1981, 1965
    Truck Model:
    81-C20 Silverado Camper Special-TH400-4.10s; 65-C20 with 4:57 gears and Borg Warner Overdrive
    Engine Size:
    Carb'ed Vortec 350; 1972 L48 350
    Backlash, slop. I agree, a manual shouldn't make that noise. That's why I asked if something may be loose or flopping. You can get refurbished gopros on ebay for a decent price, and then acquire some clamp style mount and you see all kinds of neat stuff going on under the vehicle.
     
    Last edited: Jan 7, 2021
  9. Frankenchevy

    Frankenchevy Lying Dog-Faced Pony Soldier

    Posts:
    4,757
    Likes Received:
    4,969
    Joined:
    Jan 3, 2018
    Location:
    USA
    First Name:
    Jeremy
    Truck Year:
    Square
    Truck Model:
    CUCV
    Engine Size:
    Small
    I don’t know about that, seems I have more will than skill. My willingness is strong though.
     
  10. Dutch Rutter

    Dutch Rutter Full Access Member

    Age:
    31
    Posts:
    865
    Likes Received:
    813
    Joined:
    Aug 13, 2013
    Location:
    Independence, Or
    First Name:
    Joshua
    Truck Year:
    1984
    Truck Model:
    K20
    Engine Size:
    5.7
    It does sound quite backlash like. But if it we're mine I'd hate to tear it all back apart and find something else to be the problem after all that work.

    My 700r4 had a VERY similar sound which went away after it was replaced. Thinking that was a missing internal pin at the rear of the trans (no idea the actual name of the part).

    Even took it to a few shops who came up with all kinds of things, from rear gear lash, to TC, to lash in the trans output and TC input shafts, basically alot of shotgun diagnosing.

    Do you happen to have an old cellphone in a drawer that can record video? If so tape that SOB under there.
     
    DoubleDingo likes this.
  11. DoubleDingo

    DoubleDingo Drain The Swamp, Completely

    Posts:
    6,174
    Likes Received:
    5,323
    Joined:
    Jul 3, 2012
    Location:
    Right where I am
    First Name:
    Bagoomba
    Truck Year:
    1981, 1965
    Truck Model:
    81-C20 Silverado Camper Special-TH400-4.10s; 65-C20 with 4:57 gears and Borg Warner Overdrive
    Engine Size:
    Carb'ed Vortec 350; 1972 L48 350
    That's what matters, and being thorough, which you are. But even the great ones miss something once in a while.
     
    Dutch Rutter likes this.
  12. Frankenchevy

    Frankenchevy Lying Dog-Faced Pony Soldier

    Posts:
    4,757
    Likes Received:
    4,969
    Joined:
    Jan 3, 2018
    Location:
    USA
    First Name:
    Jeremy
    Truck Year:
    Square
    Truck Model:
    CUCV
    Engine Size:
    Small
  13. Dutch Rutter

    Dutch Rutter Full Access Member

    Age:
    31
    Posts:
    865
    Likes Received:
    813
    Joined:
    Aug 13, 2013
    Location:
    Independence, Or
    First Name:
    Joshua
    Truck Year:
    1984
    Truck Model:
    K20
    Engine Size:
    5.7
    I think your right about it being internal. If it just was one "clunk" kind of sound I'd think something rocking into something else. But that kind of "ker-clunk" sound... I'd be pulling it back down, somethings not right.
     
  14. Frankenchevy

    Frankenchevy Lying Dog-Faced Pony Soldier

    Posts:
    4,757
    Likes Received:
    4,969
    Joined:
    Jan 3, 2018
    Location:
    USA
    First Name:
    Jeremy
    Truck Year:
    Square
    Truck Model:
    CUCV
    Engine Size:
    Small
    I agree. The company I bought it from said to drive it 10-15 miles and see, but that’s a scary idea. They said they would send me another one. I’m going to call again tomorrow. I’ll put on my lift springs this weekend so I have at least a little sense of accomplishment.
     
    bucket likes this.
  15. bucket

    bucket Super Moderator Staff Member

    Age:
    39
    Posts:
    23,109
    Likes Received:
    9,527
    Joined:
    Aug 3, 2010
    Location:
    Usually not in Ohio
    First Name:
    Andy
    Truck Year:
    '77, '78, '79, '84, '88
    Truck Model:
    K5 thru K30
    Engine Size:
    350-454
    Drive it a whole bunch and work it hard to see what happens. If it gets real bad, just tell them it happened in 10-15 miles.
     
    68post and DoubleDingo like this.

Share This Page