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Weird vibration problem

Discussion in 'The Hokey Ass Message Board' started by milner142790, May 16, 2013.

  1. milner142790
    Joined: Apr 21, 2009
    Posts: 87

    milner142790
    Member

    When I had the driveshaft made I had it measured so the slip yoke was bottomed out and pulled back out 1 inch


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  2. I believe the 904 came out in 1960 and the 727 in 62 or 63. These were both 3 speeds and a big improvement over the earlier automatics. The early 904 had a "6" designation and used for slant six motors. When the 273 and 340 v8 motors came out the 904 lost its 6 designation and was used in all 6 cyl. and small block motors. The HP 340 and 360 motors used a version of the 727 as did all big blocks from then on. The two are very simular in design and if it is true that you have a 904 trans then the motor is not a 400 BB but a small block because I do not believe anyone made an adapter to bolt a 904 up to a BB.
     
  3. woodiewagon46
    Joined: Mar 14, 2013
    Posts: 1,408

    woodiewagon46
    Member
    from New York

    I think the clue is that the longer you drive the vibration gets worse. What is your rear tire psi? As you drive the tire and air gets hotter and hotter, just an idea.
     
  4. milner142790
    Joined: Apr 21, 2009
    Posts: 87

    milner142790
    Member

    Then it has to be a 727 because I know for a fact it is a 400.


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  5. Dan Timberlake
    Joined: Apr 28, 2010
    Posts: 1,238

    Dan Timberlake
    Member

    I have an electronic vibration analyzer that measures vibration and can display the individual vibration "frequency" which is frequently related in some way to rpm of the problem component.
    http://www.maintenanceworld.com/articles/coxj/vibrationpen/diagram1.jpg
    It can save a lot of trial and error when troubleshooting vibration problems.

    If you were close to Eastern Mass we could go for a ride.

    Here is a link to a reed tachometer.
    http://www.jackssmallengines.com/Parts-Lookup/19200 /304830/ps?gclid=CKfY6c3OnbcCFUee4AodhTcAbA

    It could be used to identify the frequency of the vibration(s?) you are feeling at 45 mph.
    If its about 600 rpm or cpm it is related to tires and wheels.
    Driveshaft balance or sometimes seized u-joints would likely be more like 1500-1800 rpm.
    U-joint angle issues, sometimes seized u-joints,or super soft trans mounts or axle mounting usually is twice driveshaft rpm, 3000-3600 in this example.
     
  6. The combination of the 400 and the 904 still sounds
    strange to me. Chrysler may have put the two together in
    some applications but I've not seen it.

    So my thinking keeps going back to the 400 being
    externally balanced, as previously mentioned. And then
    maybe the 904 got added on at a later time. And if the
    torque converter from the 904 was used and it was from
    an internally balanced engine, that might be the source
    of a vibration.

    The Torquflites used balance weights welded to the
    converter, not to the flex-plate. Any converter is
    likely to have at least a small weight attached to it to
    balance just the converter. For use with an externally
    balanced engine, there will be maybe two larger weights,
    possibly a couple inches long. Hard to describe here but
    a websearch will probably show you the specific
    difference.

    This isn't really dependant on the transmission type.
    Either way, an externally balanced engine will require a
    specific torque converter, as well as the harmonic
    balancer, I believe.
     
  7. Von Rigg Fink
    Joined: Jun 11, 2007
    Posts: 13,428

    Von Rigg Fink
    Member
    from Garage

    All I can give you is my experiance in something close.

    440 with 727 trans vibrated like a bitch, knocked out screws vibrated the floor and my feet...turned out it was the wrong torque converter...some need to have balance weights , some not..I changed the TC and all my problems went away...well, the vibration problem on that car went away

    if it aint that, than keep lookin

    well , i see claymart has a quicker keyboard;)
     
  8. milner142790
    Joined: Apr 21, 2009
    Posts: 87

    milner142790
    Member

    Figured it out today! I ended up putting a 5/16 shim in the tranny mount to raise it up and change the driveshaft angle. All is well now! Well... For as good as it can get with it being 60 years old and mostly original equipment


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