Turbo 400 transmission question.

Discussion in 'The "Juice Box"' started by eagleguy, Nov 14, 2019.

  1. eagleguy

    eagleguy 1971 Skylark Custom

    Did the Turbo 400 automatic transmission found in a 1970 BBB come with an adjustable modulator or was it non adjustable?
  2. johnriv67

    johnriv67 Well-Known Member

    All were non-adjustable. The only way to adjust one was modify it. Not worth it, just buy the adjustable modulator for like $15
  3. eagleguy

    eagleguy 1971 Skylark Custom

    I have been told the whining noise my car (1970 Chevelle SS/ Turbo 400 trans) makes mostly in park but occasionally in drive and reverse is being caused by a faulty pump in my transmission. Noise sometimes is real loud but on occasion there is no noise at all. Transmission shop stated that if the noise is not that bad and if I do not have shifting issues I could leave it alone. I however, am of the opinion that its not a good thing to drive around with a pump going bad as it could lead to some really serious issues. I am considering getting the unit rebuilt now to be on the safe side but by a different sop. Opinions?

    I have been getting quotes at around $1500 for a rebuild with premium parts including a new torque converter.
    Last edited: Nov 16, 2019
  4. eagleguy

    eagleguy 1971 Skylark Custom

    I also have new deep pan that was installed last year with new fluid and filter. Is it possible the filter has disloged somewhat or is leaking past its o-ring is causing the intermittent whining?
  5. BrunoD

    BrunoD Looking for Fast Eddie

    Stupid question! with the deep pan,I would think you installed a deeper pick-tube?We all do it automatically,but we also all make mistakes.Otherwise,most likely the filter is loose a bit,like Bill stated.Bruno.
  6. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    I agree you should drop the pan and take a look at the filter and O ring. Make sure it is secure and all sealed up.

    To answer your question about the stock big black modulator, technically, they were adjustable. If you look at the threaded rod that extends from the modulator, you'll notice sealant around the threads where it exits the modulator. Any adjustment would break that seal, and you would need to reseal it after adjustment as it would leak vacuum without the sealer. RTV would do the job I imagine.
  7. eagleguy

    eagleguy 1971 Skylark Custom

    I did not install the new deep pan, change the filter or add the fluid. It was all done while the car was in the shop last year for other things and I was told the OEM pan was bent and leaking. Hence the replacement. Knowing the shop I would hope they used the correct filter. I will be dropping the pan and see if there are any issues before going the rebuild route. Pulled my back and for the last few weeks I have been unable to lay flat under the car! Thanks for all the insight!
  8. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    Filter is the same. The deep pan takes a longer filter tube and shouldered bolt and spacer so the filter sits lower.

    For the GM Deep pan (Part # 8679994)

    The extended pipe is part # 8629526

    The longer filter bolt is part # 8633208

    The bolt spacer is part # 8629523
    Last edited: Nov 20, 2019
  9. eagleguy

    eagleguy 1971 Skylark Custom

    Thanks for the info. Just did not expect a problem a year after the work was done but stuff happens. Rather check first then spend $1500 unless I have to. Like I said I have no shifting issues at the moment. Mechanic who worked on my car made me a deal. If I buy the filter and fluid he said he will swap everything at no charge so we can see if the o rings and filter are the issue. I will also inspect the pan for metal shavings.
    Last edited: Nov 21, 2019
  10. eagleguy

    eagleguy 1971 Skylark Custom

    Hey guys. Car has sit a bit but I am getting ready to drop the pan. How much fluid will I need and what filter parts should I be getting. I understand Larry gave me some part numbers but I plan on going to Napa. Will they cross reference?
  11. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    Steve, those are the GM [part numbers for the GM deeper pan. I posted them many years ago when I bought those parts. They may no longer be available. You might get lucky with a sympathetic GM parts person.

    With a stock pan, you'll need about 4 qts. and the filter. You can get that anywhere.

  12. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

  13. eagleguy

    eagleguy 1971 Skylark Custom

    Thanks Larry,

    Dropped the pan today. Pan and magnet were spotless. Filter was as tight as......... and had not dropped. O rings and everything else looked fine, no issues. Put everything back and added new fluid with some Red Lube Guard. Whine noise was a little less so we will see what happens.

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