top of page
  • Phantom

Swapping 4L80E into Phantom's 2003 AWD Silverado SS

Ok guys. After watching the video of me swapping in a 4L80e into my 2003 Silverado SS, I realize I didn't necessarily show you exactly how to do this. Fortunately for you all, I'm better at typing out the process than I am actually demonstrating it. So, here goes.

As mentioned, you won't need any fancy tools. You'll need:

15mm socket (medium length wobble socket will make your life easier) and 15mm wrench

13mm socket (medium length wobble socket will make your life easier) and 13mm wrench

10mm socket/wrench

17mm wrench

21mm socket/wrench

11mm wrench

8mm Allen wrench or 8mm Allen socket

Snap Ring Pliers

Needle nose pliers

24mm socket

Long 1/2" ratchet

Good crescent wrench

3/8" impact is helpful

1/2" impact is helpful

Parts needed:

4x4 4L80e transmission with torque converter

Flex plate from 6.0/4L80 vehicle

Flex plate bolts from same vehicle

Crankshaft spacer 12563532

4l80 torque converter bolts

4l80 dip stick tube 15832205

4L80 shifter cable bracket 15013290

Speed sensor Pigtail

Cross member from DTR Fab LLC or modify your stock one

Front Driveshaft from GM 2500 series 4x4 vehicle with 4L80

New rear driveshaft or have your stock driveshaft shortened

Mark Williams 32spline input adapter for NP149/4L80 or send your stock one in to someone to be modified

Pump Rub Kit - optional/recommended by monkey

1350 series pinion yoke - optional

TruCool 40k GVW trans cooler - optional/recommended

Atomic Fab TruCool 40k GVW trans cooler mounting bracket

Russell 640380 fittings

ICT 551124 fittings if using newer case 4L80

ICT 551114 fittings if using older case 4L80 (fittings close together)

4x 90* -6AN hose ends

15' -6AN Hose

4 Gallons of your favorite ATF

1350 series pinion yoke for 8.5" 10bolt - optional/recommended

If doing the 1350 series pinion yoke go to your local parts store and get a pinion seal for a 1985 1/2ton chevy truck with 8.5 10bolt rear end

First things first, disconnect your battery

Get the truck up in the air, either with a lift or a jack

Hopefully by now you've presoaked the 6 15mm nuts that hold the factory y-pipe to the exhaust manifolds. Get those nuts off. 3/8 impact with an extension and the 15mm socket should make quick work of this.

Now undo the 4 15mm nuts at the rear of the y-pipe

Get the y-pipe out of the way

11mm wrench and loosen the 4 bolts holding the straps over the front driveshaft u-joints

Get front driveshaft out of the way

17mm wrench to loosen nut on shift shaft on driver side of transmission

Remove shift linkage from shift shaft

13mm wrench and remove two bolts holding black box on driver side of transmission and remove that box

Unplug all electrical plugs and remove miscellaneous brackets on transmission to prepare for removal

Remove the two 13mm bolts on the starter. Move starter out of the way

Grab the 24mm socket and long 1/2" ratchet and place the socket on the crankshaft bolt

While looking up where the starter was, watch the flex plate as you rotate the engine with the socket and ratchet until you see the first flex plate bolt. Use the 8mm Allen wrench or Allen socket to loosen bolt. Repeat steps on next 2 bolts

Use 15mm socket to loosen drain plug on transmission pan and let fluid empty out.

Move to the rear with your 11mm wrench and undo the 4 bolts on the rear ujoint. Remove driveshaft and set to the side

Now the first fun part. Use a 15mm wrench, preferably a stubby wrench and loosen the 6 nuts holding the transfer case to the transmission. The top one will SUCK

Separate the transfer case from the transmission. Using a floor jack or trans jack or if you're a man like me, your arms and wiggle the transfer case out from between the trans and torsion bar crossmember

Watch the following video to show you how to open the transfer case and install the pump rub kit. Once you're in, you'll see how to install your new 32spline input adapter as well

Once you're done there and the case is re assembled and clean and ready for install, leave it on the bench and go back under the truck.

There are, or should be 7 bell housing bolts holding your transmission to the engine. One of those for sure will be a studded bolt with a 13mm nut holding the dipstick tube to the transmission on the passenger side. There could possibly be another studded bolt on the driver side at the top with a 13mm nut securing a ground wire. Using your 13mm socket, remove that one, or two, 13mm nuts.

Using your 15mm socket or wrench, loosen the 7 bellhousing bolts on the transmission.

Place a floor jack or transmission jack (depending on whether or not you're on your back or using a lift) under the transmission pan

Use the 15mm socket to loosen the 2 nuts on the tail shaft mounts inside the crossmember

Use the 21mm socket and wrench or crescent wrench and loosen the 4 bolts/nuts on the transmission crossmembers sides

Set crossmember to the side.

The transmission is now ready to come out. So, carefully wiggle it off the dowls and lower to the ground.

Hopefully you bought the conversion crossmember from DTR Fab LLC. If not, you'll need to research on how to modify your stock cross member to use with a 4L80

Using your 15mm socket, remove the 6 bolts holding your flex plate to the engine. Remove flexplate

Install your new flex plate/crankshaft spacer/longer bolts

Slide the new dipstick tube up into place

Transfer tail shaft mount from 4L60 to 4L80

Now slide that new 4l80 transmission up into its new home. Make sure you're not smashing any wires in between the engine and transmission

You'll be able to install 5 bell housing bolts. Hopefully you took note of which holes had the studded bolts to secure your dipstick tube and grounds

Install transmission crossmember and 15mm nuts to trans tail shaft housing

Your 4L80 converter likely has 6 bolts. Use the same process you used to remove the old bolts to install the ones. Use red locktite on each bolt

Install black electrical box on driver side of transmission

Install shifter cable into bracket and onto shift shaft

Time to re install the transfer case.

Be sure to lube your shaft lol

I don't know any good way to tell you to install the transfer case. I manually lifted it off the table, carried it over to the truck, lifted it up in between the crossmembers, and then slid it on the output shaft of the transmission.

Now reinstall the 6 sucky to reach 15mm nuts on the transfer case studs

Fill transfer case with 3qt of whater fluid you choose for that. I used the same fluid that I will fill the transmission with

At this point, lets tackle the little bit of wiring. You've either purchased the conversion harness from frost or you you're going to do it the cheap way. Here is a link to help you repin your harness on the cheap

Once that's complete, plug in the rest of your electrical for the transmission as well as reinstall all the miscellaneous brackets

Install your new front driveshaft and tighten the 4 11mm bolts for the u joint

Hook up your transmission lines. You've either chosen to reuse your stock lines, which is fine, or you're going to install an aftermarket unit like I did. Either will work

Reinstall your factory y-pipe and connect to catback

If you chose to install a 1350 series rear pinion yoke, now is a good time to do it. Using an 1 1/4" socket, remove the pinion nut

Tap the old pinion yoke off

Using a hammer and a "chisel" remove the factory pinion seal from the rear end housing

Carefully tap your new pinion seal in

Slide the new 1350 pinion yoke on.

Reinstall pinion nut with some red loctite

If you've chosen this route, you'll need a driveshaft that is 70" from center of rear u joint to center of front u joint. IF YOU DIDN'T INSTALL A 1350 PINION YOKE, YOU'LL NEED TO MEASURE FOR THE PROPER LENGTH DRIVESHAFT.

Slide driveshaft onto output shaft of transfer case and then bolt into pinion yoke.

We're close!

Lower vehicle so you can fill transmission. I like to start with 10 quarts. (will likely end up taking 12-13 quarts)

Reconnect battery

If you chose to use the Frost conversion harness, this thing is ready to fire

If you chose to repin your factory harness, you'll need to segment swap your pcm with a 4L80 transmission segment. Super easy to do. Search HP Tuners for a link to do so.

Fire it up! Run through the gears, check fluid, add more if necessary.

Test drive it, and enjoy!

7,272 views0 comments

Recent Posts

See All
bottom of page