Adapting the GM 4L80-E Transmission

to the

Jeep Dana 300 Transfer Case & FSJ NP Transfer Cases

Novak's 4L80E transmission to the Jeep Dana 300 or Early New Process (or New Venture) transfer cases conversion makes for one of the strongest geartrains possible for both on-road and off-road, and has become an increasingly popular transmission to transfer case combination.

The adapter is compact at only 3.0" long for a combined transmission and adapter length of 29-1/4" (equivalent to a ~22-5/8" manual transmission). The adapter itself is machined of a 6061 aluminum alloy, featuring thick flanges and a heavy cross-section.

There are three different styles of kits to join a 4L80E to these transfer cases:

  • "A" Kit: replacement 4L80E output shaft version, 23 splines, keeping your 23 spline Dana 300 or New Process transfer case input shaft
  • "B" Kit: replacement Dana 300 input gear version, 32 splines, keeping your 4L80E 32 spline 4wd output shaft
  • "C" Kit: replacement New Process input gear version, 32 splines, keeing your 4L80E 32 spline 4wd output shaft

If you're unsure about what kit you need, the "A" version covers your bases, so long as you don't mind having your 4L80E opened up and built.

All versions and years of the 4L80E can be adapted to the Dana 300 and FSJ NP (Full Size Jeep New Process) transfer cases. 2wd or 4wd versions all work equally well with the adapter option that best fits your install sitation.

Option A: 4L80E Output Shaft Replacement

Adapter kit for 4L80E to Jeep transfer cases

Kit 4L83-A, adapting 4L80E transmissions to Jeep Dana 300 transfer case, output shaft version


4L83-A Kit Contents

  • Adapter housing
  • Transmission output shaft, 23 splines
  • Seal spacer
  • Seal
  • Adapter gasket
  • Seal ring
  • Fasteners
  • Steel foot for rear mount
  • Instructions

The 4L81-A adapter is compatible with all versions of the 4L80E. If you have a 2wd 4L80E, a 4wd 4L80E that is undergoing a rebuild anyway, are unsure what 4L80E you have (or will have at the time of the conversion), are missing the rear speed sensor, or your transfer case was just rebuilt (doesn’t leak) and you’d rather not open it back up then the 4L81-A kit is your best choice. The new 23 spline 4L80E output shaft is machined from stock material through an extensive process ensuring maximum strength and a precise fit. The new Novak shaft splines directly into the OEM style input shaft of a 23 spline transfer case.

The basic installation is a 2-2.5 hour bench job and will include at least simple gasket and seal replacements. Be sure that if your transmission is missing the output speed sensor it is added at this time. See below for the correct parts. This is a good time for a more thorough master rebuild and update of the Hydra-Matic.

Early vs Late 4L80E Oiling

In about 1997, GM changed the way the rear bushing is oiled in the 4L80E transmission. The shafts are not interchangeable and you will need to identify for sure which version you need.

  • The first design has two lube holes in the sides of the case bushing journal. Lube flows through these feeding the output shaft and forward to the planets.
  • The second design does not have the lube holes instead has a tube feeding oil from the valve body.
4L80E Transmission Output Shaft Lube Hole

Option B: Dana 300 Transfer Case Input Shaft Replacement

Adapter kit for 4L80E to Jeep transfer cases

Kit 4L83-B, adapting 4L80E transmissions to Jeep Dana 300 transfer case, input shaft version


4L83-B Kit Contents

  • Adapter housing
  • Transfer case input gear, 32 splines
  • Seal spacer
  • Seal
  • Adapter gasket
  • Seal ring
  • Fasteners
  • Steel foot for rear mount
  • Instructions

There is a factory 4wd version of the 4L80E which is ready to bolt up to our 4L83-B adapter kit. It features a 32 spline output shaft which protrudes about 3" from the rear face of the 4L80E transmission main case. If you have this veresion, disassembly of the transmission is unnecessary but disassembly of the transfer case is necessary to install the provided input shaft.

The input gear installation is a 2-3 hour bench job and usually includes either a simple gasket and seal replacement or a full rebuild with chain if the transfer case has many miles on it. Transfer case rebuild kits are available. See Related Products, below.

Option C: New Process 208, 218, 219, 229 Transfer Case Input Gear Replacement

Adapter kit for 4L80E to Jeep transfer cases

Kit 4L83-C, adapting 4L80E transmissions to Jeep Full-Size NP transfer cases, input gear version


4L83-B Kit Contents

  • Adapter housing
  • Transfer case input gear, 32 splines
  • Seal spacer
  • Seal
  • Adapter gasket
  • Seal ring
  • Fasteners
  • Steel foot for rear mount
  • Instructions

There is a factory 4wd version of the 4L80E which is ready to bolt up to our 4L83-C adapter kit. It features a 32 spline output shaft which protrudes about 3" from the rear face of the 4L80E transmission main case. If you have this veresion, disassembly of the transmission is unnecessary but disassembly of the transfer case is necessary to install the provided input gear.

The input gear installation is a 2-3 hour bench job and usually includes either a simple gasket and seal replacement or a full rebuild with chain if the transfer case has many miles on it. Transfer case rebuild kits are available. See Related Products, below.

Applications & Compatibility

Compatible Transmissions

4l80e_transmission_drivers_side

All versions and years of the 4L80E can be adapted to the NP (New Process) transfer cases. Both the 2WD and 4WD versions work equally well with the correct adapter option.

Output Shaft Speed Sensor

4L80E rear reluctor speed sensor

1991 - 1996 4L80E's should feature a speed sensor at the driver's side rear portion of the case (see image, below), whether they are 2wd or 4wd applications. 1997 and later 4wd applications often omit the rear sensor as this data is available from the transfer case output shaft in factory applications. This adaptation requires that this sensor and its internal reluctor ring be installed by a transmission building professional for proper operation.

See Related Products, below.

Compatible Jeeps

This conversion is compatible with all longer wheelbase (CJ7 93.4” or longer) or stretched Jeeps. The TH350 is the only real automatic option practical for CJ5 and other short wheelbase Jeeps.

These are exceptionally strong transmissions native to 3/4 ton truck and SUV applications. Full Size Jeeps such as Wagoneers, J-Trucks, etc. are conversion candidates for them. There are numerous upgrades available for the 4L80E should stock strength come into question.

Compatible Engines

Any engine that can be made to work with the 4L80E will work with this adapter. Natively compatible engines such as the 1997-2006 Vortec / LS / Gen III+ engines are far and away the most popular choices.

Keep in mind that if you depart from a native configuration on the engine, you will need an aftermarket controller for the transmission as these are electronically controlled both in the shifting and pressure. Without a controller you’ll only have reverse, third gear and max line pressure; probably not the best solution for a Jeep.

Lastly, be aware of Gen III engine crank spacing, 4L80 flexplates, and torque converter heights. This is not much of an issue where installers have pulled a factory matched engine / transmission combo as their donor, whereas those who are mixing and matching LS components should verify accordingly. We've written a helpful guide to GM crank spacing here.

Transfer Case Clocking & Rotation Options

Our adapter is drilled for multiple clocking locations. This will permit the installer to optimize the angle of the transfer case. However, shifters, clearances and other considerations may be limiting factors.

Rear Mount Provision

This transfer case adapter's design features a modular mounting and support system and mounting base, ready to accept our industry standard urethane isolator mount, available in Related Products, below.

Related Products


Urethane Rear Mount for Crossmember
4L80E Output Speed Sensor OSS
Auto transmission cooler
4L80E 4wd output shaft
4L80E 4wd output shaft
1976-1986 Jeep floor tunnel cover
Dana 300 Rebuild Kit
Billet aluminum Dana transfer case pan
Dana 300 Super Short Tailhousing
TurnKey 4L80E Transmission Package

Installation Requirements

Tools

Tools required will vary depending on which kit is selected. The automatic transmission takes more specialized tools and knowledge, gaskets, seals, snap ring pliers, etc. The D300 input will require bearings be pulled and pressed on the input, in addition to typical mechanic's hand tools. The 208 requires hand tools, large snap ring pliers and RTV to reseal. Rebuilds are a little more involved, but not much.

Placement

Transmission placement is largely determined by factory engine location. It is not necessary in typical conversions to change the engine position unless an engine is being swapped in at the same time as will often be the case with these kits. Setting the powertrain to the proper factory or conversion pitch angle - usually tilted down ~5 (3-7 acceptable) degrees - is recommended. Consult our engine conversion guides for more specific recommendations on placement if the engine is being replaced.

Clocking Information & Driveshaft / Yoke to Pan Clearance

Use of the factory size driveshaft and yoke is recommended. Our adapter design has maximized clearance between the transmission pan and yoke, but it is necessary that you install your GM engine offset 1-1/4" to the driver's side. If you are installing against a factory AMC engine with our 437-AMC adapter kit, your factory engine should already have this proper offset. Our adapter is drilled for multiple clocking locations from near-factory (20 degrees down) to near-flat (3 degrees down). However, pan clearances and front axle width may inhibit the flatter options.

Engines & Engine Mounting

If converting to a V8 in conjunction with this upgrade, aftermarket engine mounts are available to ease its installation. Because of the broad spectrum of engines and vehicle combinations used with this adapter, it would be difficult to list them all here. Whatever your application, Novak likely has the perfect solution. From a 225 Buick V6 in a CJ2A, to an LS3 in your JK, we’ve got you covered.

GM Engine Mounts for Jeeps

Novak's engine mounts, featuring excellent vibration dampening, superior strength and impressive adjustability - adjustable even after the engine is installed. The design, strength, and affordability of our mounts are second to none.

Engine placement in these applications is an effort in compromise to find the best position overall as a package. Generally the engine will be about 1” or even more towards the left, (driver’s side in the USA) away from the front differential in a CJ application. This gives the best balance of weight and more importantly clearance for the driveshaft going to the front axle. your tight spots will be steering to exhaust on the left (hold that as tight as you can) and clearance for the front driveshaft on the right. Fore and aft position will vary with the Jeep model and engine. Have a CJ5 and Gen I with a rear distributor? you’ll be better off a little forward for more rear driveshaft length and clearance for that HEI. If you are in a longer Jeep and using an LS engine with no distributor, you’ll have more fan clearance and better balance if you hold it to the rear. Usually for ground clearance tuck things up nicely for height to avoid damage to oil pans and other life giving parts in the Jeep. Common sense and taking a step back to look at things overall goes a long way.

Driveshafts

Driveshaft length changes are often required. Most conversions to these transmissions will require that the rear driveshaft be modified to be shorter and front driveshaft longer.

Some installers, concerned about the expense of new or modified driveshafts, attempt to let the existing driveshafts dictate engine, transmission and transfer case location, often to the detriment of the project. Our recommendation is to prioritize the correct position of drivetrain components over saving a few dollars which is usually regretted in the long run with compromised positioning.

Driveshaft modifications and rebalancing can be affordable when performed by driveline, RV or tractor implement specialists. New driveshafts are an option, but not necessarily a requirement in regards to the actual successful conversion if your existing driveshafts are in good condition.

Jeeps that require extensive travel or specialty-built driveshafts have this option available through several fabricators across the nation. These are normally specified after placement of the new transmission and measured at vehicle ride height. As the rear driveline gets shorter, it is often advantageous to us a Double Cardan or “CV style” rear shaft with the correct geometry at the axle to minimize vibrations and possible binding.

Axles

Use of factory axles is completely acceptable with this conversion. Axle upgrades are not necessary, but they may be chosen for reasons external to this transmission upgrade.

Also See