455 and TH400 with a transgo shift kit question

Discussion in 'The "Juice Box"' started by guyrobert, Aug 22, 2019.

  1. guyrobert

    guyrobert Guyrobert

    My 75 LeSabre convertible has a 455 with stage1 heads and a TA 212 Cam.
    I recently had the transmission repaired and they added a Transgo shift kit 400-1&2
    It is shifting very hard into second even at slow speeds.
    As this is a cruiser, the bang when it goes to second is starting to bug me.
    Unfortunately the shop (Wilf's) near me that did the work has sold the property and closed.
    Is the Transgo shift kit adjustable so I don't get the hard shifts into 2nd?
    Also if any one could recommend a transmission shop to do the work in Vancouver B.C. it would be appreciated
    Thanks Robert
  2. Dwayne B

    Dwayne B Well-Known Member

    I installed one in my TH350 A couple years ago and in came with two different springs to choose from. One was for the street and the other was for the Strip .
    I installed the street spring and it has A nice crisp shift in 2nd and 3rd.
    It kinda sounds like someone installed the strip spring in yours making it hit really hard.
  3. guyrobert

    guyrobert Guyrobert

    Thanks for the info, that is what it feels like, If I really accelerate hard it doesn't seem as noticeable but for cruising around town it is a pain!
  4. 1969RIVI

    1969RIVI Well-Known Member

    X2 on this^^ I just did my th400 with the same kit and used mostly the street parts but drilled the holes in the separator plate larger than their recommended specs since their hole sizing is very conservative. I also did alot of other mods and upgrades to make the trans stronger and better. Talk to member Bens99gtp on this site he's got alot of really good info. I'll try and add some links of his for you to read.

  5. guyrobert

    guyrobert Guyrobert

    Thanks for the info, I will have to have a shop do any adjustments as I simply don't have the space or place to do the work myself....
  6. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    If you have an adjustable vacuum modulator, you could try adjusting it for softer minimum throttle shifts. If you don't have an adjustable modulator, get one and try adjusting it.
  7. Bens99gtp

    Bens99gtp Well-Known Member

    I'm not familiar with the trans go kit as I never buy a shift kit, it's just easier to do it without one, so without know fully what other mods they did it will be hard to tell you how to soften it up.

    But my guess is the hole in the plate is too large and if so it will take a new separator plate, or a stk one to start with.
  8. Bigpig455

    Bigpig455 Fastest of the slow....

    and the correct amount and location of checkballs - read the shop manual
  9. Bens99gtp

    Bens99gtp Well-Known Member

    Some checkballs can be omitted, some can't. I would have the li e pressure checked as well, some shop put a larger spring and then shim it way up, you dont need 200,250 psi to make these hold and last. In fact if too high of pressure and cast iron sealing rings are used, you can actually turn those things into tiny saws inside the trans........
  10. guyrobert

    guyrobert Guyrobert

  11. scubasteve455

    scubasteve455 Well-Known Member

    i bought that kit
  12. 1969RIVI

    1969RIVI Well-Known Member

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