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Thread: 4L60E to 4L80E conversion in a GMT900

  1. #1
    Join Date
    Nov 2003
    Denton Texas

    4L60E to 4L80E conversion in a GMT900

    Finally finished the 80e conversion. Damn, I need a lift in the worst way, my shoulder blades are raw from crawling around on my back under the truck all day.

    What all I had to do to pull the old trans out....

    Remove passenger side fender well liner to aid in the process
    Disconnect positive lead from battery
    Set e-brake and chocked the rear tires
    Remove front two O2 sensors for access to exhaust nuts
    Remove y-pipe from manifolds and muffler assembly
    Unbolt the shift lever from the trans and remove the shift selector switch and set aside
    Remove the u-shaped clip holding the shift cable to the bracket and remove cable from bracket
    Unbolt fuel lines mount bracket from driver side of case
    Unbolt 15mm nut at trans rubber mount on tailhousing. It is inside the access hole in the bottom of the xmember.
    Remove four 21mm nuts at crossmember
    Put oil catch can under tailhousing and remove driveshaft
    Remove trans pan and drain fluid into catch tub. I use a large Rubbermaid so I don't miss a drop.
    Put the pan back on.
    Remove starter
    Remove convertor bolts
    Jack up crossmember to take the load off bolts and then remove the 4 bolts
    Lower transmission until the oil pan rests on the front xmember. trans xmember will fall off. Remove vent hose from trans xmember.
    Use a wood block or plywood to protect the trans pan and jack trans assembly back up so you can remove the exhaust y-pipe assembly.
    Lower transmission back down
    Remove heat shield on passenger side
    Remove speedometer pickup wiring on tailshaft housing
    Remove large wiring harness on passenger side of trans behind heat shield by squeezing the sides
    Remove trans cooler lines, top is return, bottom pressure side. Slide plastic covers back and take a pick to remove the retainer wires inside the fittings to remove the hoses.
    Using a 4 foot long extension and swivel, remove the three 13mm nuts holding the fill tube, vent tube and fuel lines brackets
    Jack transmission back up and remove fill/dipstick tube, remove jack
    Place transmission or motorcyle type jack under transmission and put light support on the transmission.
    Using a 4 foot long extension, remove all the 15mm bellhousing bolts. Lower bolts can be removed with a regular short socket setup.
    Remove the transmission assembly and take care to not let the convertor fall off. A bolt into the convertor tab and mechanic's wire or zip tie to the inspection hole will hold it in place.

    My 2002 80e has a transgo HD2 kit, vacuum mod kit and PI Vigilante 10" 3500 stall convertor custom built to mount to a standard truck/LS1 flexplate.

    Install procedure...

    Install convertor and make sure it's seated all the way. Tie it back using mechanics wire so it doesn't slip out. Put bolts in the cover holes and run wire across the convertor lug to hold it in place by wrapping the wire around the bolts.
    I have a piece of masonite placed on the ground to slide the trans out or to put it under the truck to prevent scraping up the pan.
    A motorcycle jack with plywood on it works good to install the trans. A ratchet straps across from one side of the frame to the other was used to hoist it up high enough to get the jack under that heavy pig. After you get the transmission high enough to get the jack securely under the trans just jack it up to installation height. Getting the trans at the right angle is a little tricky when you're doing it by yourself. Using a ratchet strap from the jack, up and around the tailhousing to pull it to same angle as the engine works well.
    Install transmission as normal and check that the convertor has space between the flexplate and the convertor during install.
    Tighten all the 15mm bellhousing bolts
    Install the vent tube bracket at the top center stud, 13mm nut and vent tube to the transmisson vent. Tube will be the stock rubber hose from the 60e.
    Install the fuel hose bracket to the top bolt on the left using one 13mm nut
    Jack up transmission to maximum height and install new 80e oil fill tube and secure with the last 13mm nut.
    Measure clearance from flexplate to convertor lugs. If greater than 3/16" then place appropriate thickness washers to get correct clearance. Use bolts supplied by convertor manufacturer. Longer bolts will be needed if you have to use washers greater than 1/16". You may have to buy longer bolts and cut/grind to correct length.
    Install convertor bolts loosely in all three holes and then tighten after last is installed.
    Install starter
    Lower transmission, again
    Install cooler fitting c-clips
    Stretch the bottom cooler line out by removing some of the bends to fit to the front cooler fitting.
    The top line is the return line and needs to be cut and a piece of tubing or transmission cooler quality hose needs to be used to extend it to fit into the rear center support return fitting. Installing two clamps per end of hose is suggested when using rubber hose to prevent possible leakage should one come loose. -AN compression fittings can be used along with braided hose rather than cooler hose. In my instance a piece of 3/8" tubing and two compression fittings was used. These compression unions are available at any hardware store. A piece of 3/8" steel fuel line can be used in place of the transmission cooler tubing.
    Snap the cooler hoses into the fittings and give a good tug to make sure they're securely fastened and then slide the plastic retainer clips over the cooler fittings

    Driveshaft mod...
    The worktruck has a steel driveshaft and has 1.188 diameter ujoints caps, 1350s, same as my 80e slip yoke. No puney 1.06 or 1.125 1310/1330 size joints. Installed a new ujoint while swapping the 80e slip yoke onto the old driveshaft.

    Crossmember mod...
    Modify the xmember by cutting off 5" from each end. Use 4" x 1/4" thick plate 10-1/4" long to move the xmember back to the mount location. It ended up being 5-7/8" that I had to shift the mount toward the rear.

    Wiring mods...
    Remove K(orange), V(light blue), S(white), T(tan/black) and U(brown) wires from transmission connecter. Move U(brown) wire to the S location.
    Front Input Speed Sensor (ISS) is made by using the orand and light blue wires. Add a VSS connector, connect orange to terminal A and light blue to terminal B. Move the low signal wire from pin 45 to location 26 in the TCM harness.
    Install the front Input Speed Sensor wiring connection
    Install the shift selector switch on the driver side you removed from the 60.
    The factory speed sensor can plug back into the 80e tailshaft sensor

    Conversion is finished, had to get a 2008 Chevrolet Express 4.8L/4L80e van C2500 TCM tune to get the transmission to shift correctly. There was nothing special done to make the TCM work in the Silverado, just swap them out. The TCM was loaded with a factory tune for an 80e transmission, thanks for the help there Nathan.

    Type: Chevy Express (V8) 2008
    VIN: 1GCGG25C481106014

    Segment 1: 24239927
    Segment 2: 24235887
    Segment 3: 24251658
    Segment 4: 24235883

    I did not have to buy HPTUNERS licenses for the new tune since its just the TCM. Now I need to learn how to tune these POS E38/T42 PCMs. Without the 80e TCM tune there was no speedo output to the PCM and the tune would not enrichen the fueling when accelerating.
    Last edited by RedHeartbeat; 04-29-2010 at 06:48 PM.
    See my truck data in the "My Garage" section here... http://www.ls1truck.com/forums/my-ga...tml#post191709

  2. #2
    Join Date
    May 2008
    Schertz, Tx
    Nice write-up Greg!

    07 Z71 4x4, 6.0L, 3.73s, Turbonetics T76 @ 10 psi, 75 shot, Snow meth kit, PLX DM-100 wideband gauge, Nelson tune, Comp 212/216 .557/.561 114 lsa, 60# injectors, Yank 3000, 4L80E , Magnaflow - dumped, e-cutout
    Line-X, Pace Edwards Full Metal Jackrabbit bedcover

  3. #3
    Join Date
    Oct 2009
    Reidsville, Georgia
    Yep, this will definately help inform people in the future, I've done 4 80E swaps now, and they get easier every time!
    2000 2-toned silverado, Totalled. Gone But not Forgotten.

    Now: 2002 black rcsb chevy. 5.3, P&P 862's, Comp 224/230 .58*/.59* 114 LSA, Racetronics 44lbers, ARP 2000's, Ebay long tubes, 4L80E, 3800 yank pro, transgo HD-2, 4.10's, True-Trac, Walbro 255, Nitrous Outlet plate setup for 200, 80mm BBK, 3" Magnaflow, and Raggedy traction bars! Waiting to be istalled, F.A.S.T LSx intake..........

    Best: 7.40@90 1/8th


  4. #4
    Join Date
    Nov 2008
    Spring, TX
    def vote for sticky
    '02 Silvy: Z71 EC Step Side 5.3L Nelson tuned
    2013 GMC Acadia: SLT1 Carbon Black
    1976 Corvette Stingray: Trying to save it, progress is slow.

    ^Ricky's Sweet PS Skilz
    09/21/2010 02:31 <danger_ranger83> I'm not really worried about the looks...I want it to be fast and ugly...bc no one wants to get outrun by something ugly

  5. #5
    Join Date
    Feb 2010
    did u get any pics.. while u were down there?

  6. #6
    Join Date
    Nov 2003
    Denton Texas
    Updated TCM information
    See my truck data in the "My Garage" section here... http://www.ls1truck.com/forums/my-ga...tml#post191709

  7. #7
    Join Date
    Jun 2010
    RedHeartbeat: I have to remove the shift lever from the tranny so I can beef up the ball stud that attaches to the shift cable.
    You may not have ran into this when you removed yours, but on mine the nut
    as well as the threaded stud is rusty. I'm afraid if I wrench on it too much I'll break something in the tranny - and I can't hit it with heat because of the
    switch behind it.
    Any thoughts?

  8. #8
    Join Date
    Nov 2003
    Denton Texas
    leave it on the shaft. Drop the pan and remove the nut that holds the shaft to the shift mechinism inside the transmission. Unbolt the shift selector and unplug the harness and pull the whole assembly out at once.
    See my truck data in the "My Garage" section here... http://www.ls1truck.com/forums/my-ga...tml#post191709

  9. #9
    Join Date
    Aug 2007
    honestly are you happy with the way the 80e is vs the 60e? do you street race or just race it at the track?
    2008 GMC CCSB 6.2/6L80e swap
    Gen IV 5.3/60e swap 1994 ecsb W/T

  10. #10
    Join Date
    Nov 2003
    Denton Texas
    Mine is a DD / weekend racer with a 3500 stall. The 80e takes some major abuse and keeps on ticking. My 60e behind the 4.8L was toast after only 40k miles. My only complaint about the 80e is the fact that the convertor unlocks on deceleration, with a loose 3500 stall it's a PITA.
    See my truck data in the "My Garage" section here... http://www.ls1truck.com/forums/my-ga...tml#post191709

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