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So you want to install a 4L80E? Learn from my mistakes (and successes!)

Discussion in 'Chassis / Drivetrain / Suspension / Wheels' started by 454GrandPrix, Nov 11, 2017.

  1. 454GrandPrix

    454GrandPrix Master Mechanic

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    (Prologue: It seems that every time I mention my 4L80E transmission in this forum, somebody asks me for information about how I installed it. As I search around, I can find only one or two old threads with a few scraps of info... but it seems there isn't one all-inclusive thread to discuss the entire process. I'm hoping to change that now. Please remember that there is always more than one way to skin a cat. I tend to go for the low-buck Roadkill method whenever I modify my car, though I am not above spending a bit of money for something that is well engineered or that can save me significant amounts of time and/or headache. In other words, if you want to do something differently than I explain below, well, go right ahead--after all, it's your car. With that said, here we go.)


    So you say you want to install a 4L80E into your G-body. Great! I put one in my 1980 Grand Prix, and I'm sure you can install one in your G-body as well. Let me guide you through the process--detailing the hijinks and heartaches, my failures and successes--so that you can pull this off with as little cursing as possible. There are a number of things you need to consider, and I'll attempt to address them all in a more-or-less systematic order.

    Consideration #1: vehicle body prep

    Good news: nothing outrageous is required. In fact, I did not hammer/dent/reshape any portion of my transmission tunnel or my firewall. I just dropped my 454/4L80E into the car and it fit. However, I later learned the transmission bell housing's left 'ear' contacts the trans tunnel--I should have cut that off. Oops. In my case, I've just been letting it "self-clearance" as I drive... which works, kinda, but it does transfer extra vibration to the interior. Cut the ear(s) off in advance and you should be golden.

    Consideration #2: transmission prep

    As I said above, my 4L80E is bolted to a 454. Both the transmission and the engine came out of a 1999 Chevy Express 3500. I already mentioned cutting off the ear(s) of the bell housing. Other than that, the only prep I performed on the transmission was a trans pan R&R to install a new internal filter, then I filled it with new fluid. I reused the stock converter.

    Consideration #3: mounting it in the car

    I used stock Monte Carlo SS frame mounts on the engine cross member + my donor van's stock engine clamshell brackets in order to mount the engine. For the rear transmission mount, I simply ordered the G-Force 4L80E crossmember. It bolted right into place, and the transmission bolted right to it. Because my G-body pre-dates the 4spd transmissions, I did need to also install the driver's side frame extension piece that they offer... but even that was a simple matter of drilling a couple holes and bolting it into position. You can see the extension here:

    [​IMG]

    The G-Force piece is very well engineered, and it makes installing a 4L80E very simple (and it also perfectly cleared my dual 3" exhaust system). I am not a paid spokesman, but I endorse it completely.

    [​IMG]


    Consideration #4: connecting it to your axle

    This is as straightforward as it gets. I took some measurements, then went to a local driveline specialist and had him fab me a driveshaft. Easy.

    Right behind the G-Force crossmember is the stock "driveshaft loop" bracket. When I installed my driveshaft, its u-joint was directly above that little bracket, and it would contact the bracket when the shaft spun. I quickly removed that bracket from the car. This didn't bother me, as I'm sure I'll install an NHRA-approved driveshaft loop at some point in the future.

    Consideration #5: fluid cooling

    There was no way I was going to try to adapt my stock V6 cooler lines to the 4L80E. Instead, I bought some lengths of steel brake line plus a handheld tubing bender, then I bent the lines into shapes that would work. At each end, I flared the tube and used rubber hose to connect it. At the transmission end, I needed some fittings to connect these rubber hoses to the housing. Because I had not modified my trans tunnel, I needed fittings with 90^ bends in them so I'd have room to attach the hoses. After looking at every part store in town, I found an old NAPA that came to my rescue: they had a dusty old cabinet with brass fittings--I literally blew the dust off the fittings as I took them out to inspect them. Here they are next to one of the transmission housing fittings:

    [​IMG]

    DON'T do what I did and wait to install these after the transmission is in the car! I barely had enough room between the trans and the tunnel to install these. Attach them to the trans while it is still sitting on your shop floor and you'll be much happier. If you plan ahead and "massage" your trans tunnel with a large hammer, you'll be significantly better off than I was. ;)

    As for the actual heat exchange, I bought the largest bar and plate (or stacked plate) design cooler I could easily find--its core measures 12"x12". (This cooler design is much more efficient than the tube design!) I mounted it in front of the radiator but not attached to it; there is probably 4" or so between the two. As an old habit from my turbo minivan drag racing days, I also put an inline fluid filter in the inlet hose just before the cooler. I did not route my transmission fluid through the radiator at all; this external cooler is all I am using for temperature control. So far it has worked well; even in the peak of my summer desert heat, I have never seen the fluid temp go higher than 165^ at any time.
     
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  2. 454GrandPrix

    454GrandPrix Master Mechanic

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    Consideration #6: gear shift setup

    My car was originally a 3spd column shift automatic. I wanted a floor shifter, and I wanted it cheap. I went junkyarding and found a FWD Grand Prix with a floor-mounted 4spd shifter (meaning it had a detent for 1, 2, 3 & D). I grabbed it and bolted it to my floor. That car's shifter cable was plenty long enough to route forward through the firewall, then down to the transmission.

    [​IMG]

    As you might guess, this shifter cable wasn't designed to operate this transmission. I was determined to make it work. The cable was determined to fight back. In the end, I used a small L-bracket to hold the cable to the bell housing so that the cable can operate the shift arm. Well, it sorta operates the shift arm. It shifts smoothly through P-R-N-D, but then the angle gets funny and it doesn't want to shift down into 3 or 2 or 1. This is all I need to operate the vehicle, so I've just lived with it... but it really bugs me. I'm probably going to have to bite the bullet and spend money on an aftermarket shifter eventually. You might want to do that up front.

    But whichever shifter you decide to use, DON'T do what I did and wait to install it until after the transmission is in the car! I was worried about the cable length, so I waited to make sure it would let me mount the shifter where I wanted it. Eventually I drilled four holes in my transmission hump, then went to bolt in the shifter. The two rear bolts were not too difficult to install. The front left bolt was very tricky, and I needed a neighbor kid to help by attaching the nut from inside the car while I was lying underneath the car holding the bolt in place. The front right bolt was just plain impossible; there was so little space between the top of the trans and the tunnel that I could not figure out any way to maneuver the bolt into the hole from under the vehicle. Oh, well; three bolts will have to work. Be smarter than me--install your shifter while the trans is out of the car.

    One other failure with my shifter setup is this: currently I am in no way interfacing with the neutral safety switch. This means I have no reverse lights. It means I can shift my car out of Park without having my foot on the brake. It also means I can start the engine while the transmission is in gear. That last fact will likely cause me problems when I visit a drag strip and try to pass their tech inspection, so I will need to address this shortcoming soon. (I am working on finding the NSS wiring diagram so I can craft solutions to this problem.) Just one more thing you should think about when contemplating this swap.

    Consideration #7: transmission controller

    In case you didn't know, the E in 4L80E stands for Electronic. That means this transmission requires some sort of computer to operate it (unless you convert it to a manual valve body, but I didn't want to go down that rabbit hole). Because my engine is carbureted, I needed some sort of standalone controller. You have a variety of controller options. After reading a comparison test in Car Craft magazine, I decided on the TCI EZ-TCU. I mounted the TCU on my inner fender:

    [​IMG]

    This unit comes with very detailed instructions, and installation is very easy. They even give you a handheld controller for the initial setup (no laptop computer required!) and to make programming changes at any time. You don't need to leave the controller plugged in at all times, but I chose to do so in order to use its screen to monitor the trans fluid temperature. For the curious, there are two live data screens you can monitor; here is a picture of both of them:

    [​IMG]

    I'm still not a compensated endorser, but I really like this controller. Setting it up is a snap; you just enter your trans type, R&P ratio, tire size, do a TPS calibration, then you twist the key and start driving. Out of the box, its stock programming suits my driving personality very well. You can customize to your heart's content, telling it to change how soon it locks up the converter, or to shift firmer (or softer), or how aggressively to hold gears before shifting, etc. For example: out of the box, the default programming does not let the converter lock up before 50 MPH. With my 3.08 axle ratio, I thought that was fine. After I re-geared to 3.55, I decided I wanted the ability to lock up a little sooner, so I changed that down to 45 MPH just by pressing a few buttons. Easy.

    The EZ-TCU also offers numerous additional 'hardware' options, such as support for a normal/performance mode switch, support for paddle shifters, and more. It does everything I want it to do, and yet I feel I'm not even using half of its capabilities. I just don't think automatic transmission control gets any better than this.

    Consideration #8: speedometer

    Before doing my engine & trans swap, I had already installed an AutoMeter GPS speedometer in my car. However, it had some quirks that I didn't care for. After the swap, the speedometer suddenly began getting electrical interference and worked very erratically (when it worked at all). At that point, I swapped it out for a more traditional AutoMeter electric speedometer. The TCI EZ-TCU gives you a loose wire with a speed output signal, so all I had to do was connect that to the input wire on the new unit. Done.


    Anyway, that's an overview of everything to consider when deciding to drop a 4L80E into your G-body. Did I miss anything? Do you need additional clarification about how I did something? Just let me know. OTOH, if you installed a 4L80E into your G-body and you want to explain how you did something differently, please post away and show us what you did. I'm sure we'd all love to see it. :)
     
    #2 454GrandPrix, Nov 11, 2017
    Last edited: Nov 13, 2017
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  3. Anubis

    Anubis Royal Smart Person

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    Nice write up. Thanks for sharing. I installed a 4L80E as part of my LS swap and cut off both ears with a sawz all to facilitate header clearance. For those searching for a used 4L80E keep in mind that GM made a few changes in 2004 you need to know about. Most notably the PRNDL is not a 7 position like most older overdrive transmissions. This means you cannot manually select gears 3-2-1 on the new models unless you have the BCM wired and paddle shifters to electronically change it. For those doing an LS swap I highly recommend using the factory transmission controller (they are plentiful in the junk yards and cheap!) For newer CANBUS ecm's like the E38 you can use a T42 transmission controller shown below. GM used them most every platform including 4 cylinder FWD cars. Most of the other 99-2003 ecm's have a built in transmission controller so no additional cost there.

    I am using factory lightning rods with the 4L80E connected via a B&M cable and bracket kit. When installed with the 4L80 lever kit there is no fabrication required and it bolts up like GM would have installed it. Very clean and easy with no slop.

    [​IMG]
    [​IMG]
    [​IMG]
     
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  4. 87National

    87National Greasemonkey

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    Nice write-up. I'm surprised more folks aren't going the 4l80e route behind carbed SBC and BBC engines.

    These transmissions are fairly plentiful in salvage yards nowadays. For someone on a tight budget, you could use the standalone gm trans controller from a mid to late 90s diesel truck. Factory crossmember can be modified. For a few hundred $ you can have the strength of a th400 along with the OD and TC lockup of a modern trans.
     
    #4 87National, Nov 11, 2017
    Last edited: Nov 11, 2017
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  5. olds307 and 403

    olds307 and 403 Royal Smart Person

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    I am seriously considering one for my 70S. Used 2wd versions from vans come up all the time for sale. I know an adapter is needed for an Olds V8. I am thinking of Jake Shoes manual control unit and some line pressure improvements. How much longer is it than the 2004R and TH350? I assume they use the TH400 32 spline output? A 2004R needs so many parts to live, a 4L80E needs what a shift kit to live behind big power? I need a similar, easy to use OD shifter. I just removed the TCI Fastgate shifter in my G body, hated the reverse lock out. Need one that will fit with a bench seat. Great thread
     
    #5 olds307 and 403, Nov 11, 2017
    Last edited: Nov 11, 2017
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  6. UNGN

    UNGN Royal Smart Person

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    Very nice. What did you do about the Speedometer?
     
  7. Anubis

    Anubis Royal Smart Person

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    Dakota digital for me.
     
  8. 454GrandPrix

    454GrandPrix Master Mechanic

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    OOPS--I forgot to mention that. I'll go back and edit that into my info. Thanks for the reminder!

    If you're installing an LS engine--and therefore using a factory computer to control your EFI--it obviously makes tons of sense to also use the factory computer to control the transmission.
     
  9. abadwillys

    abadwillys Apprentice

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    Excellent write up, i love my 4L80, one of the best upgrades ive done to my car, i "dimpled" my trans tunnel slightly for that rear cooler line clearance, and used 90* AN fittings because i have braided stainless cooling lines, I cut the ears off too, knowing that they always cause an issue, Im using the same home made X -member i made 28 years ago with my TH400, just cut the mount off the front because the 4l80 mount landed right on top of it so i just drilled a hole for the stud, sorta like that G-Force X member, I also had a custom driveshaft made with billet yokes, I use a Hurst Q-stick/B&M Pro stick shifter, so that was just a matter of buying a 7004R gate plate and swapping that in to my shifter. I am a carbed BBC as well, so i used a CompuShift Controller, very happy with it, Completely programmable thru my dash mounted display screen, i also have a A-B mode switch and can switch between a "Cruising" Shift to a "Race" shift with a push of a button. My Trans display will show MPH but i may put Autometer speedo in my dash, as i put a Autometer Tach in my dash last year, Pretty easy swap no biggie and well worth it imo..
     
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  10. mr evil

    mr evil Moderator
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    Stickied this....
     
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