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non-lock-up t/c on lock-up tranny?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by 4x4_76, May 23, 2002.

  1. 4x4_76

    4x4_76 1/2 ton status

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    Last week I bought a new torque convertor on my trucks TH-350.I think it's lock-up version,not sure.It has green wire going in on left side of the tranny.
    Anyway,I called to part-store and asked that can I use non-lock-up convertor in this tranny,because I don't have anything that controls lock-up.Guy told me that yes,you can.So,I ordered it,changed it and tranny worked fine.
    Yesterday,when I was accelerating on road,I was manually up-shifting,1st,2nd,and when I hit 3rd,engine revved almost to limiter.I thought that I accidentally shifted to neutral,so I rolled on side of the road.I shifted to 1st gear.Nothing.All gears were gone,including reverse.20 miles and torque converter was broken!
    I just called to a part-store that sold me that convertor,and guy(not one who sold it) told that it's not possible to use regular t/c on lock-up tranny.
    WTF!!Who can I trust?
     
  2. RedDwarf

    RedDwarf 1/2 ton status

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    Well, I have swapped in a lockup tranny and convertor to a non-lockup truck and it worked so if you put in a lockup convertor it should be ok.

    Not sure about the convertor not fitting, though aftermarket high stall jobs are mostly non-lockup....

    My guess is something else in the trans is messed up...did you flush the trans really well (what color is teh fluid now)?
    Are you sure it is full of fluid?
     
  3. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    Sounds like either the pump went or the forward drive drum clutch went out. Might be something as simple as a jammed piston in the valve body. If it was the converter and it say snapped the impeller off the shaft I would think it would make some ugly noises
     
  4. 4x4_76

    4x4_76 1/2 ton status

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    When I was stranded ona side of a road,I tried to listen any unusual sounds,but didn't notice anything.
    Last evening I was wondering that what went wrong,and started the engine.Still didn't hear anything.But when I shut down the engine,I heard very clearly somekind of rattling sound.


    RedDwarf,

    Oil is red as it should be,and there is plenty of it.I didn't flush tranny.
    Convertor went in nicely,I did have thoughts of it not fitting,but since it fit,and I could actually drive it,I was thinking that everything is fine.
     
  5. Blue85

    Blue85 Troll Premium Member

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    You might want to check on the length of the splines that engage the torque converter on the two versions of the tranny. Perhaps you just barely had spline enagement and it worked for a while, but then you stripped out the ends of the splines?

    This doesn't sound like a torque converter failure.
     
  6. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    Blue is right about the splines. As the tranny ages the stator shaft (the part stiong out of the tranny that the converter rides on) get worn pretty bad. I had to replace mine when I rebuilt my tranny.
    Now let me ask you this. Will it go into park? If it goes into park then My guess above is correct. If it doesn't hold in park......Check your transfer case and make sure it's in gear. If your still running the transfer case full time it may have broke the chain. Should have made a lot of REAL nasty noise when you came to a stop.
     
  7. dyeager535

    dyeager535 1 ton status Premium Member

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    Isn't the input shaft length different on a lockup/non lockup tranny?

    I was under the impression that the conversion "kits" included a new input shaft....the later transmissions IIRC (like the 700 and 200) had an extra "nub" on the end of the input shaft, with a checkball, that might bottom out on a non-lockup converter, before its fully seated in the pump. (meaning if it doesn't seat, you strip out the pump, and no pump means no movement)

    If you have only one wire, and it's a '76, it wouldn't be lockup anyway, probably that weird timing idea GM tried for awhile with a tranny switch of some type.
     
  8. 4x4_76

    4x4_76 1/2 ton status

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    Thanks for your help,guys!

    I found non-lock-up convertor from garage,that was on my brothers C-10.I could see just looking in there that splines are deeper in non-lock-up convertor than in lock-up convertor.
    I measured the difference,and it was 14,5mm(0.57inches).
    So,when I accelerated and hit the 3rd gear,it screwed the splines.

    I can't do nothing to it at least for a week,because I have broken rib.Luckily I have sparepart TH-350,where I can take the input shaft if it has broken splines.

    Well,at least next time I remember measure turbine from INSIDE,too.
     
  9. dyeager535

    dyeager535 1 ton status Premium Member

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    make sure the pump "tangs" aren't what stripped out. A poorly constructed TH400 converter (too thin overall) stripped the tangs out of the pump in my car.
     

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