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4L40E rebuild question(s)

This is a discussion on 4L40E rebuild question(s) within the Automatic Transmission forums, part of the Drivetrain category; Back in the day a hi stall speed TC did just that all the time. A 3500 rpm stall didn't ...

  1. #21
    Exalted Cyclops 67CamaroRSSS's Avatar
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    2002 Z28 A4 NBM
    Sadly now demodded :(

    Back in the day a hi stall speed TC did just that all the time. A 3500 rpm stall didn't go into lock up until you hit 3500 rpm.

    Today's TC's have a "lock up" function where the TC will flash higher than stock when moving in traffic until you hit a certain speed (say 40 mph) then it will go into lock up regardless of engine rpm.

    Imagine this: Light turns green and you accelerate normally from the light. Engine goes up to about 2500 rpm, shifts to 2nd then shifts to 3rd then goes into OD, all that time at 2500 rpm. When you get to 40 mph then the TC goes into lock up (the speed where the TC goes into lock up can be changed via HP Tuners or similar). That feels like another shift and the rpm's will go down to what it would be normally (as if you didn't have a high stall TC). If you mash the throttle the tranny will down shift normally while the TC will flash up to it's rated stall speed. This puts your engine into it's power band.

    The area that will cost you mileage is leaving lights as the stall is up until it goes into lock up. That and the fact you'll wanna mash the throttle all the time (shit eating grin factor) will result in about 2 to as much as 5 mpg less than stock depending on how you drive.

    For comparissions sake a stock TC has a stall speed of ~1800 rpm so you can see that a 2200 stall isn't that much higher than stock. Most of us opt for a higher stall speed (3400 in my case) as we don't care about losing a few mpgs. In my case it's not my DD so 3-4 mpg less than stock isn't hurting me at all. On the hiway mileage isn't affected as it will be in lock up most of the time while cruising.

  2. #22
    Member godless-phoenix's Avatar
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    Blackened fire chicken
    2000 Pontiac Trans Am WS6

    i thought the stock stall was 1,600??? i havent 100% decided yet on the TC, so its not too late ;P but tony's the one telling me that 3,400 might be too high for DD and reccomnded i get 2,200-2,400 stall TC...i told him i wanted 3,400 haha...well see i guess, whatever, just fix the damn thing! hahaha
    Last edited by godless-phoenix; 01-06-2011 at 04:19 PM.

  3. #23
    Exalted Cyclops 67CamaroRSSS's Avatar
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    2002 Z28 A4 NBM
    Sadly now demodded :(

    I'm not exactly sure what the stock stall speed is but I've been told 1800 rpm. That's why I put a tilde (~) sign in front of it as that sign is considered punctuation used to indicate the word "approximately".

    Please note that rebuilding the tranny with such items as a stainless steel sun shell, more clutches and a shift reprogramming kit are things that are generally done to a tranny that is to be used for "severe duty". Also, a tranny cooler is a good thing to have whether or not you have a higher stall regardless of the application. With a higher stall it becomes a must have item due the heat generated by the TC.

  4. #24
    Member godless-phoenix's Avatar
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    Blackened fire chicken
    2000 Pontiac Trans Am WS6

    oh ok ~ gotchya...tony told me it was 1,600 rpm, thats why i wondered, its not that much of a difference anyway ;P so, right now i have a diablo tune in my car, and i cant reflash the pcm back to the factory settings cause someone stole the tuner. would i need to re-tune the car for the "improved" tranny?

  5. #25
    Moderator Cutlass's Avatar
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    1999 Formula WS6 M6-sold
    2001 Silverado Z71

    2200 to 2400 is old school thinking. 3500 is where the LS1 likes it.

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