Register now to get rid of these ads!

Technical Th400 “clunk”

Discussion in 'The Hokey Ass Message Board' started by anthony myrick, Apr 26, 2021.

  1. Just installed my th400/caddy combo.
    The trans has a torque converter noise. No issues before the swap. I have a BOP adapter with the correct converter spacer and hub adapter.
    The noise is louder when cold. Not as noticeable when warm.
    Fluid is fresh and at the correct level.
    The noise was noticeable on first firing and got quieter as we finished filling the trans.
    Still has a noticeable “clunk” coming from the converter area. Any you guys experience this?
    Thanks.
    We didn’t notice this noise when we had it bolted up on the run stand. But used a different converter and trans with the same BOP adapter. Also didn’t have an exhaust on it either.
     
  2. squirrel
    Joined: Sep 23, 2004
    Posts: 55,939

    squirrel
    Member

    video? with sound?

    Clunk sounds like something that happens once...is it continuous, repeating, occasional, or what?
     
  3. Joe H
    Joined: Feb 10, 2008
    Posts: 1,525

    Joe H
    Member

    Loose converter bolts make a lot noise.
     
  4. Clunk going from reverse to forward and back again,,,,,,or continual clunk ?

    Tommy
     

  5. '51 Norm
    Joined: Dec 6, 2010
    Posts: 827

    '51 Norm
    Member
    from colorado

    Some time ago I went through a TH400 and when I was done I discovered that I had not installed the anti-clunk spring. Yes that is what it is called. And what it does.
    Naturally it is the first thing to go into the case and I got to experience the dismantle and reassembly a second time.
    The spring doesn't look much like a spring, more like a piece of wire that has ben run over by a train.
     
    winduptoy likes this.
  6. Budget36
    Joined: Nov 29, 2014
    Posts: 13,174

    Budget36
    Member

    Seems like clunking when you start it, the quieted down while adding fluid? I’ve nothing to offer, just trying to clarify the issue.

    Also, seems the trans is not a BOP, since you mention an adapter, could be a place to start looking?
     
  7. They are tight.
     
  8. Continual. Even in park.
    Follows RPMs
     
  9. Continuous.
    Less noticeable when warm.
     
  10. BJR
    Joined: Mar 11, 2005
    Posts: 9,814

    BJR
    Member

    I had that happen on a 400 behind a 472 Cad. Turned out the stock converter to flex plate bolts were too long for the new converter, and were bottomed out but not tightening the converter to the flex plate. Put in shorter bolts and noise was gone.
     
    ottoman and Kevin Ardinger like this.
  11. I measured and cut them.
    I thought the same thing. They’re not bottomed our.
     
  12. bchctybob
    Joined: Sep 18, 2011
    Posts: 5,190

    bchctybob
    Member

    Flexplate to crank bolts tight? Are they the correct bolts? Shoulder too long so they torque but don’t clamp?


    Sent from my iPhone using The H.A.M.B. mobile app
     
  13. SS Pete
    Joined: Jan 13, 2017
    Posts: 48

    SS Pete
    Member

    HI, I ran across a similar case years ago. You did not say what Caddy motor, 429 or 472 ? I had a BBC with a BOP trans. The dowel pins on the block were not long enough to extend into the trans bellhousing with the adapter. check that also. Pete.
     
    anthony myrick likes this.
  14. They do not come all the way through the trans, about 1/2 way
    500 caddy
     
    Last edited: Apr 26, 2021
  15. Yep.
     
  16. Check the bell housing bolts. Tight.
    The dial pins go 1/2 way into the trans.
    I used the “stethoscope” trick around the bell gliding bolts. No noise.
    It seems to be coming from the pump area.
     
  17. TA DAD
    Joined: Mar 2, 2014
    Posts: 1,107

    TA DAD
    Member
    from NC

    So using an adapter you have to space the converter back ? is the nose in the crank like it should be ?
     
  18. The spacers are between the flywheel and converter. A hub adapter is there for the converter and crank.
    I was kinda wondering it that part may be the source. It slides on easily.
     
    Last edited: Apr 26, 2021
  19. Did you install a shift kit? HRP
     
  20. triumph 1
    Joined: Feb 9, 2011
    Posts: 591

    triumph 1
    Member

    I would definitely take a close look at the hub spacer. Possibly see if it moves while assembled with a long pick or similar. I don’t think there should be any movement & possibly that could be your noise.


    Sent from my iPhone using H.A.M.B.
     
  21. No. bone stock
     
  22. TA DAD
    Joined: Mar 2, 2014
    Posts: 1,107

    TA DAD
    Member
    from NC

    I am working on a project with a T400 and if I space the trans back with a mid mount ( 1/4 in. ) I will have to send the converter back to have the nose extended. I would not like a spacer in there. But that is just me.
     
  23. I’ll check that soon
     
  24. Used this adapter.
    3628EF2B-FA39-43A4-8B9C-BAF97A5D2470.jpeg
    The thick washers they sent were supposed to be stacked. My OCD didn’t like that so I bought 3 spacers the same thickness as the adapter plate.
    The hub adapter (circled) could be the source)
    Wonder why it’s quieter when warm? Expansion?
     
    Last edited: Apr 26, 2021
    VANDENPLAS likes this.
  25. TA DAD
    Joined: Mar 2, 2014
    Posts: 1,107

    TA DAD
    Member
    from NC

    Wish I could be of more help, did you have the trans in operation in the donor ? More than likely it will have to come back out, that sucks !
     
  26. squirrel
    Joined: Sep 23, 2004
    Posts: 55,939

    squirrel
    Member

    hmmm...maybe on a TH350? the TH400 uses a bolt to hold the center support in place, it does not have a spring, but the TH350 does.

    th350.jpg

    Anyways...video with sound will really help us hear what you're hearing.
     
    Kevin Ardinger and 427 sleeper like this.
  27. My video skill suck. Will work on getting one
     
  28. I’ve seen flex plates and torque converters make all kinds of clunk noises, now an adapter and a spacer in there. It’s where I would look.

    I have had a few converters come apart internally and make noise, but when that happens you either have a severe lack of power or no drive at all.

    Can’t see it being a pump knocking at I would think it would be a catastrophic failure pretty quick and no noise after that:D
     
    Truckdoctor Andy likes this.
  29. Yep. This thing drives and shifts perfect.
     
    VANDENPLAS likes this.
  30. lippy
    Joined: Sep 27, 2006
    Posts: 6,825

    lippy
    Member
    from Ks

    Slots for the pump wider on the convertor than the tangs on the pump? Since you said it's a different convertor. Lippy
     

Share This Page

Register now to get rid of these ads!

Archive

Copyright © 1995-2021 The Jalopy Journal: Steal our stuff, we'll kick your teeth in. Terms of Service. Privacy Policy.

Atomic Industry
Forum software by XenForo™ ©2010-2014 XenForo Ltd.