Trouble with my TH400 S/P!

Discussion in 'The "Juice Box"' started by Tim, Oct 12, 2004.

  1. Tim

    Tim Silver Level contributor

    I bought a used '67 Th400 S/P for my 72 Skylark I installed a B/M shift kit and had TSP build me a 12" converter and for the first 800 miles everything was fine.
    Recently I noticed a whining coming from the tranny when I was driving and didn't think much of it but it seemed to get louder lately, it sounds like when you would put in second or first gear manually and it whines.
    Anyway the other day when I first started driving it, (the tranny was cold) at about 25mph the tranny would shift back and forth between second and third.
    I kept driving it and it quit doing this once the trans warmed up.
    I then decided to see if it did anything strange under a load so I floored it from a stop in drivs, second gear came in fine at about 5,100rpms but third gear was slipping at 5,300rpm's and actually hit 6,000 before slowly shifting.
    The trans used to shift right at 5,000rpm.( a little low for my combo)

    The trans fluid is all new and looks clean and full.
    What do you think it could be?
    Thanks
    Tim
     
  2. simon1243

    simon1243 Got Torque?

    i had the same problem with my th400. when i finnally tokk it out and had it rebuilt it turned out that there wasnt any friction material left on the clutch packs. just a thought
     
  3. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    Tim,
    I hate to say it, but there's really no way to diagnose that problem on this board. Too many things can be wrong. All I can tell you is to check the basics. Check the fluid level, and condition very carefully. Make sure the modulator is good and it has a good vacuum supply that is leak free. If you installed the B&M kit yourself, it may be related to that. The whine might be the front pump. In any case I wouldn't drive the car with a slipping transmission. You are doing damage. If the line pressure is low, and not increasing at wider throttle openings, the clutches will slip and overheat. Take it to a transmission shop, and let them run some oil pressure tests. That's what I would do.
     
  4. Tim

    Tim Silver Level contributor

    Ok thanks guys.
    Tim
     
  5. buick535

    buick535 Well-Known Member



    The things that can cause a whine on the t-400 are, torque converter, front pump, or a loose filter. My guess here would be in the pump, since you are having shifting problems and now slipping.
    If you di not engage the pump tangs on the converter correctly, the tranny can work good for a while, then as it starts to destroy the pump, things will start to act funny. This cindition will often not show up as burned fluid right away, but will show lots of metal in the pan.
    The tranny is gonna need to come out. Jim Burek
    P.A.E. ENTERPRISES

    www.paeenterprises.com
     
  6. Tim

    Tim Silver Level contributor

    Thanks Jim.
     

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