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trans prob or is it

Discussion in 'The Garage' started by gravydog, Jul 16, 2005.

  1. gravydog

    gravydog Registered Member

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    I got a mind boggler for every one it in an 88 full size with a 350 and 700r4
    the problem is under a light acceleration the trans seems to shift back and forth from 2nd to 3rd at about 30 to 35 miles per hr. but under a normal or a harder acceleration it is fine and usually shifts at about 45. now thats the symptom I had reason to belive that the tv cable was at falt so I played with that alittle and ended up burning up the trans to I put another trans in it correctly adjusted the cable and still had the same problem so I have reason to belive that it is not the trans. I reasently purchesed a parts blazer for the trans and a few other parts that ran well. I relaced the rear with 3.73s org was 2.73 and swaped throtle bodies and gave it a tune up and the problem still existed. the motor seems to pulsate in drive and if you tap the throtle and let off quickly the idle will drop to 500 rpm then rise to 680. which led me to belive that there may be a vaccum leak or a distributer problem. another thing I tryed to manuely thift through all the gears and if you stift in second at about 35 to 40 mph it acts like it is shifting into 3rd but I think it is a pulse that feels like a shift since the rpm doesn't change I might have to hook up my laptop to it and watch the rpm. I don't know am I looking in the right direction I have never had a problem lihe this before. has any one ever had this problem. all I know is that this one does it and my other dosn't. please reply
     
  2. k5guyva

    k5guyva 1/2 ton status

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    Mine does that with a similar setup... 350/700R4, but I'm running a carb... I'm about to put a shift kit in to stop that.
     
  3. unclematty

    unclematty 1/2 ton status

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    Hey fellers, read up a bit here and a few other places, the 700r allthough a OK tranny, is notorious for that little problem, Notsure what to do to cure it, Maybe a shift kit like one gentleman said in a previous post :crazy:
     
  4. original balzer

    original balzer 1/2 ton status

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    i was told its a servo problem and the fault is that the overdrive is behind the other gears what ever the hell that means i say sm465 swap is in your future lol


    balzer
     
  5. gravydog

    gravydog Registered Member

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    let me know how that works out. because I have also heard that by changing the springs on the governer can effect shift point also
     
  6. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Sounds like you're feeling the convertor locking and unlocking. There are a couple of things that make the convertor unlock, one is brake application. To confirm it's the convertor unlocking and locking drive it at a steady speed and without changing throttle input lightly touch the brakes...you should feel the 'shift' and the rpms should slightly increase.

    The difference between locked and unlocked can be as much as 200 rpm.

    Rene
     
  7. k5guyva

    k5guyva 1/2 ton status

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    Thats not this case for mine... The locking system is disconnected. It showed up really bad when I was towing my boat.
     
  8. Brocky

    Brocky 1/2 ton status

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    My rig was doing the same thing and it turned out to be the kickdown on the carb. I was ready to pull my tranny out and a tranny repair guy told me to adjust the cable. I am really not sure if this is any help, but just passing on what I learned. :)
     
  9. gravydog

    gravydog Registered Member

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    now I really dont think it is a trans related problem nor do I think that it is an over drive issue because when I have it in 2nd under a light load even under a normal load the motor will pulse at about 30 to 40 mph depending on the load almost feels like a shift but doesnt actually go into another gear un less I have one of those rare 700r4 5 speeds. so I am sort of leading to ither vaccume or ignition. I hooked up a vaccume gauge and apon start up I was reading about 21 vaccume then once it approched opperating temp the gauge will pulsate between 22 and 19 and rpm reads between 602 and 680 and when i held throtle at 1000 rpm and let go the rpm would drop to 510 then raise agian. I sprayed some gum cutter around the intake and got the idle to drop one time but couldn't get it to do it agian. I also noticed that there was a coolant leak in front of the #2 cylinder probably comming from the coolant flow near the front so I think I have a vaccume leak comming from the #2 cylinder intake port I guess since I need intake gaskets any way because of a coolant leak It wouldn't hurt
     
  10. gravydog

    gravydog Registered Member

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    I have actually tried that,and I held the brake up hill and still the problem remains this is one of those ****ty ass drivabilty problems that I seem to be married to
     
  11. Thunder

    Thunder 3/4 ton status

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    I'm having a similar problem which has got more noticible lately.
    I have a miss that is really noticible at the 2-3 shift. with light load.
    The miiss is around 2Krpm. Definatly not a tranny problem.
    I have pretty much narrowed it down the the ignition. Gona put in a new set of wires. If that doesn't do it guess I'll put in a new pick up coil in the dist.
     

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