Transmission dilemma 4l80e / th400

Discussion in 'The Garage' started by Thomas Fournier, Sep 6, 2020.

  1. Thomas Fournier

    Thomas Fournier Registered Member Premium Member

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    Hello all,

    I have pretty much decided to go with a 4L80E swap in my 1977 K20 pickup. It has a sbc 350, np241 and 4.56 gears. Unless there is some new information as to why i need to scream down the freeway at 2900 rpm....im gonna go with a 4L80. I know the th400 is a badass trans but mine is getting old and i have no idea how many miles are on it. I could spend 2000 and just get the 400 rebuild with some awesome speed parts thrown at it but o/d sounds amazing on long trips.

    my BIG dilemma is whether or not to go with a junkyard pull out of a 4wd 2002-2006 chevy pickup (about $650 where im from) or whether to buy a remanufactured one (2000 give or take) I dont have a core so i would have to front a core charge on a new one. Anyone have any experience with used trans or with this particular swap? I know it would be best to buy the new one, however, i dont want to blow my budget on this thing. I do have a boss (wife).

    I priced out the TCI EZ-TCU with a vss pulse sender for the t-case (i have a mech speedometer) and some other goodies to include a bigger cooling pan, braded hoses, massive external cooler with a fan with oil for under $2000.

    i was also thinking when i get the trans and my dana 60 that i could swap gears to like a 5.38 or so. Im running 37 inch tires right now and i dont plan on going over 40 inches ever. I still want to street the rig but be super capable offroad.

    thoughts?

    if there is another feed for this question (i haven't found one) please refer me to it.

    thanks,
    -Daniel
     
  2. b454rat

    b454rat 1/2 ton status Premium Member

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    Of all the years I've been messing with cars/trucks, I've never had a trans rebuilt or bought new. I can't afford to do that. I've bought trans before that were rebuilt, but we all know how that goes. IMO theres no reason to go with a 3 speed for a street driven truck. Getting to the point where you CAN'T FIND turbo 350s and 400s anymore. And since people think they are worth a fortune, want more than what you could get a 4L80 for.
     
  3. mrk5

    mrk5 The Sticker Guy Moderator GMOTM Winner Author

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    So far I've had pretty good luck buying used transmissions that were rebuilt by the previous owner. Generally end up spending around $500.

    5.38 is too low in my opinion. I've had 5.13 with 37s in my crew cab with a 4l80e and it would be running 2400 rpm. I'd rather be around 2000 rpm for a cruising speed like 65mph.
     
  4. Thomas Fournier

    Thomas Fournier Registered Member Premium Member

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    So what your saying is get a good used 4l80. I have only had used transmissions (3 th350s that all cooked on me) in this truck except a th350 that was rebuilt at a local shop. That one tanked after about 15000 miles, so im over the local guy hookups. The th400 i have right now is working, but i dont want to be stranded somewhere with a cooked slushbox. I dont want to throw any money into this th400 if im gonna swap it either. I want to do it right the first time on this one. Im over changing out one piece of garbage for another, without killing my $$$ account.

    @mrk5 thanks for the input on gears. I was thinking 5.38 might be a little on the low side...how is your bottom end with the 5.13's? I want to get my crawl ratio down and make more low end on my takeoffs. I really dont like how doggy it feels right now. I suppose i could get the transmission first gear reduced to a 3.00 and then drop 5.13s in it....

    i really appreciate the input, gears will be a long time from now, thats expensive. Money i don't have right now. Lol
     
  5. Rick Capito

    Rick Capito Registered Member Premium Member

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    If you decide to go used I have a standalone controller with the harness, and TPS if interested PM me.
     
  6. sweetk30

    sweetk30 let it all BURN ! Premium Member

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    look at these guys for there trans controler . few members here run one and like it .

    the quick 4 unit has 4 saved programs for your driving styles you program . you can down load a test version of there program to play with before you buy it .

    www.usshift.com
     
  7. Thomas Fournier

    Thomas Fournier Registered Member Premium Member

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  8. sweetk30

    sweetk30 let it all BURN ! Premium Member

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  9. Thomas Fournier

    Thomas Fournier Registered Member Premium Member

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    @sweetk30 that one looks awesome (especially the price). I was still planning on running the factory cooler that is in the radiator after the external cooler so on cold days it would warm up and add a little more cooling. Thing i should just bypass that? I am planning on swapping the radiator at some point. maybe i should get one without the cooler to save a little money $$
     
  10. mrk5

    mrk5 The Sticker Guy Moderator GMOTM Winner Author

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    I have a 454 and a Magnum so I've got plenty of bottom end. I've been thinking about dropping all the way down to 4.56 gears.

    I think with a 350, I'd run 4.88 with 37s.

    I'm running the USShift Quick 4 that @sweetk30 mentioned. Primarily because it will accept all 3 low ranges with the Magnum.

    For a TPS sensor for the controller, I prefer this one. https://www.hgmelectronics.com/acculink-tps-kit/
     
  11. Thomas Fournier

    Thomas Fournier Registered Member Premium Member

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    @mrk5 Im running the 241 for simplicity's sake. How much does the usshift cost? I have been reading about shift point issues due to the speed sensor being on the back if the tcase.

    if i went to 40s would the 4.88 be enough?
     
  12. sweetk30

    sweetk30 let it all BURN ! Premium Member

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    if you have overdrive almost 95% here say on a auto with overdrive go DEEP . 5.13 seem to be the ticket for all around use .

    now if you have a big HP / TQ motor and or big block then you can drop down a bit in the 4.56 or 4.88 area if you want .
     
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  13. mrk5

    mrk5 The Sticker Guy Moderator GMOTM Winner Author

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    I think USShift is around $700. The price was between TCI and CompuShift when I was purchasing.

    With 40s and 5.13 I'm at about 2200rpm at 65mph. I'd still rather be closer to 2000rpm.

    I suppose it depends on the landscape where you drive most. Here in Colorado having to climb lots of high mountain passes, I'd probably consider 5.13 with 40s and a 350. If you drive mostly flatland, I would go 4.88.
     
  14. Thomas Fournier

    Thomas Fournier Registered Member Premium Member

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    @sweetk30

    looks like 5.13s are the way im gonna roll...i want it to be deep, im running 2900 rpm at 65 right now with 37s and almost no grunt on the low end. My take off sucks a**. 2500 at 65 sounds pretty amazing, especially since i can have a WAY better low end.

    @mrk5

    Over here in cali it isn't flat thats for sure... i looked at the us shift website and I'm sold on the quick 4 gen 2. Only issue i see is im running a q-jet (recently custom built by sean murphy induction) and i cant seem to find a tps that will fit it besides this one from tci which says it will only work with tci controllers....

    https://www.summitracing.com/parts/tci-377450

    i saw someone in the comments said it worked for his us shift setup. Do you guys have any experience in this field? Any other brands or models? Us shift inly has them for holly and edelbrock carbs and they don't look universal.

    Thanks again,
    -Daniel
     
  15. mrk5

    mrk5 The Sticker Guy Moderator GMOTM Winner Author

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    What about the one that I'm using? https://www.hgmelectronics.com/acculink-tps-kit/ It's not on a Qjet, but still might work.
     
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  16. Ned Kelly

    Ned Kelly 1/2 ton status Premium Member

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    Last year I enquired to USShift about what TPS to use with the Quadrajet, here is the reply:

    Question: Do you have a TPS kit that will work with Quadrajet carb?

    Hello,
    We do not, but TCI offers a remote mount/cable operated TPS adapter that works well with Quadrajets...It is available at Summit and other major parts retailers.
    --
    Best Regards,
    Jake Chandler
    Baumann Electronic Controls, LLC
     
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  17. Ned Kelly

    Ned Kelly 1/2 ton status Premium Member

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    I can't recall if someone posted this on CK5 in a different thread, but interesting info, K10 4L80e to NP205 swap:
     
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  18. Thomas Fournier

    Thomas Fournier Registered Member Premium Member

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    Did you end up installing the TCI TPS? If you did could you attach some pics of it for reference?

    @Ned Kelly

    thanks for the video. Super in depth.
     
  19. Ned Kelly

    Ned Kelly 1/2 ton status Premium Member

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    I have not done the conversion yet...just researching.
    I was also possibley considering a 6l80e (wouldn't need a doubler tc setup then) but not sure when USShift's controller will be out for that.
     
  20. Thomas Fournier

    Thomas Fournier Registered Member Premium Member

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