TH350, Rebuild or Not?

Discussion in 'Transmission & Driveline Topics' started by StrongSurvivor, Sep 27, 2017.

  1. StrongSurvivor

    StrongSurvivor Member

    33
    0
    Jun 5, 2017
    Bold Springs, GA.
    Hi Everyone,

    My '81 Z28 sat for eight years before I bought it. The previous owner tells me the trans, a TH350 was rebuilt shortly before parking the car. Should I rebuild or run it?
     
  2. CorkyE

    CorkyE Veteran Member Lifetime Gold Member

    8,819
    134
    Nov 4, 2004
    Ringgold, GA
    Run it, unless it was stored in a swamp.
     
  3. larrylarry

    larrylarry Veteran Member

    1,292
    37
    Dec 22, 2011
    San Antonio Tx
    Drive it see what it does. But be aware that there lip seals that must hold ATF at anywhere from 85 - 300 psi & when it sits for a long time the seals might leak then it won't shift for shit.
     
  4. Twisted_Metal

    Twisted_Metal Moderator Staff Member Lifetime Gold Member

    25,270
    286
    Feb 26, 2004
    Bloomington, MN
    Moisture in it will break down the clutch packs.
    If it sat indoors it should be fine.

    If it has a mushy feel to the shifts... It's time for a rebuild.
    Warm it up, check the fluid level and run it to see what it does.
     
  5. StrongSurvivor

    StrongSurvivor Member

    33
    0
    Jun 5, 2017
    Bold Springs, GA.
    Thanks everyone for your feedback. I'll run the trans as is, at least for now. Fingers crossed that it does the job. I've got enough to do as it is!
     
  6. tlcronk

    tlcronk Member

    45
    3
    Jun 27, 2016
    Coleman,Michigan
    Some years ago when taking classes for rebuilding transmissions, I was told a little secret.
    If the seals are dry from either sitting a long time or high mileage, just dump about 4 ounces of brake fluid in the filler tube.
    Start it up, and shift the gears forward and back. Do this and let it warm up and try again.
    It might take a day or two to soften the seals so they apply properly.
    Just don't expect doing burnouts right from the get go. Give it time.
    This suggestion was from my old time instructor. He worked for GM as an on the road rep./service guy back in the 50's-60's..
    Fords were especially prone with their harsher fluid.

    My $.02
     
  7. lapedr

    lapedr Veteran Member Gold Member

    459
    1
    Jan 28, 2003
    Pembroke, GA
    I rebuilt my th350 and I am not a trans expert I just made sure I followed step by step instructions, if you are going to rebuild it I have all the special tools needed and would sell them to you at a fair price, I dont need them anymore
     
  8. StrongSurvivor

    StrongSurvivor Member

    33
    0
    Jun 5, 2017
    Bold Springs, GA.
    I'm undecided about the rebuild. What special tools and how much? With shipping to 30656 please.
     
  9. lapedr

    lapedr Veteran Member Gold Member

    459
    1
    Jan 28, 2003
    Pembroke, GA
    There are special compressors bushing and bearing drivers I will look into a cost this weekend and get back to you I suggest you get a gm overhaul manual from the 70s it shows step by step with pics and spec tools I got one on amazon
     
  10. lapedr

    lapedr Veteran Member Gold Member

    459
    1
    Jan 28, 2003
    Pembroke, GA
    Below is a pic of the manual I used, it lists step by step from disassembly, to inspection, to replacement, to assembly. Also below is a pic of the special tools. I don't have all of the tools in the pic but I have what is needed to do the job. I can take a picture of what I have, and message it to you if you pm me your cell number, or post it here just let me know.
    [​IMG]
    [​IMG]
     

Share This Page