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push-starting just curious.

Discussion in 'The Garage' started by vortec, Mar 1, 2007.

  1. vortec

    vortec 1/2 ton status

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    i know push-starting works for manual tranny vehicles. slightly fun, even. but, i was just curious if it even possible with an automatic. i assume the torque converter would be a major problem in the equation.

    i don't have any intention on doing this, by the way.
     
  2. y5mgisi

    y5mgisi 1 ton status

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    not possible. Allthough i have heard tale of way older auto trannys that had rear pumps on them that would allow pressure to be built up enough that it would work.
     
  3. 83ZZ502_Jimmy

    83ZZ502_Jimmy 1/2 ton status

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    Way out of the box here.....

    I wonder if a TH700-R4 with a manual convertor clutch lockup switch could be push started? With the convertor clutch locked, is it possible? I know it will kill (cut off) the motor if it won't unlock from freeway speeds with it locked.

    Should be backwards compatible.... :thinking:

    John
     
  4. y5mgisi

    y5mgisi 1 ton status

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    Wouldnt work becasue the converter spins the pump which puts pressure on the clutch packs. No converter spin = no pressure
     
  5. vortec

    vortec 1/2 ton status

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    that's the kind of thing i was thinking. get rolling, then flip the switch and lock the tcc.

    if anyone actually successfully starts one this way, they should post a vid on here. of course, nobody will believe they didn't just turn the key.

    disclaimer: i am not advocating this action, so blame someone else when you trash a ride or crash into something.
     
  6. thedrip

    thedrip 1/2 ton status

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    I don't think it will work on a 700r4. The lockup mechanism, while triggered by an electrical switch, is actually activated hydraulically. It means unless the front pump (which is directly driven by the crank anyway, the pump isn't driven by the torque converter per-se) is spinning, it won't lock the converter up. So theres two reasons it won't work.
     
  7. dyeager535

    dyeager535 1 ton status Premium Member

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    Converter is hydraulically locked, which means that you'd have to have pressure, which means you'd have to spin the engine, which means you'd ruin the automatic transmission cooking the fluid and bearings because fluid isn't circulating while the output shaft is turning. :)
     
  8. goldwing2000

    goldwing2000 Guest

    I had an '89 Mercedes with an auto that could be push-started. Well, pull-started, really. You had to get it up to 45mph for it to work.
    I never tried it myself but the owner's manual said it could be done.
     
  9. 83ZZ502_Jimmy

    83ZZ502_Jimmy 1/2 ton status

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    Well that shoots my theory in the foot....:D
     
  10. vortec

    vortec 1/2 ton status

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    i'd say a pull-start behind an operational vehicle to build fluid pressure counts as pretty much the same thing. nice
     
  11. diesel4me

    diesel4me 1 ton status Premium Member

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    no push starts..

    Only GM tranny I know of you can push start a vehicle with, is the older Powerglide trannies ,mostly the cast iron case ones--they have a rear pump,and can be push started..but you have to get it rolling at a good clip,at least 20 mph or more--also,some old "Hydra-Matic" trannies too..no other GM automatics used after 1966 or so can be push started,AFAIK..definately not the TH350 or TH400,or 700R4's..

    Not many other tranny's had a rear pump in addition to the usual "front" pump behind the converter..so there is no way for the driveshaft to turn the engine..so don't bother pushing it!--call a tow truck!..:crazy:
     
  12. pauly383

    pauly383 Daddy383 Staff Member Moderator

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    Ford FMX trans ( 1960's ) had another pump driven by the output shaft , so push starting is possible .
     

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