Description
Adapting the GM 4L60-E (later version) Transmission to the Jeep Dana Model 300 Transfer Case and Full-Size Jeep New Process Transfer Cases
Our 4L60-E (including the 4L65 & 4L70) to the Jeep Dana 300 transfer case adapter makes for the most refined assembly both on-road and off-road, and has become one of our most popular transmission to transfer case combinations in these applications.
**Please allow 6-8 weeks for delivery as the shafts are on backorder.
Product & Features
The Adapter
The Novak 4L60E to Jeep Model 300 transfer case adapter is very compact at only 3.0" long for a combined transmission and adapter length of 25.5" (equivalent to a 17.5" manual transmission). The adapter itself is machined from billet 6061 T6 aluminum, featuring thick flanges, a heavy cross-section, and superior strength.
Transfer Case Clocking & Rotation Options
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.
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 for purchase below.
Contents
Kit includes the billet adapter housing, transfer case input, transfer case input shaft seal, transfer case to adapter gasket, transmission to adapter sealing ring, fastening hardware, steel mounting base and instructions.
Applications & Compatibility
Transmissions
The 4L63 adapter is compatible with all versions (2wd or 4wd) and years of the 4L60E, 4L65E & 4L70E transmission. We’ll refer to all these as 4L60E from now on but compatibility is all the same. For differences in these variations refer to our knowledge page linked below. There are no inherent advantages to the 2wd vs. 4wd transmissions as the output shaft will be replaced. These kits are for the hexagonal six-bolt rear pattern case made starting in 1996 and include a detachable bellhousing. Some 1999 (and earlier) versions have a four-bolt rear pattern and non-removable bellhousing. See our Kit #137 if this describes your transmission.
The new 23 spline 4L60E output shaft is machined from 300M alloy steel which provides a substantial strength upgrade even over the stock 4L70E version. The new Novak shaft splines directly into the OEM style input shaft of a 300 transfer case. This requires disassembly of the transmission, and we recommend the services of a transmission professional.
The basic installation is a 1.5-2 hour bench job and will include at least simple gasket and seal replacements. This is a good time for a more thorough master rebuild and update of the transmission. Many customers purchase one of our complete Novak remanufactured and upgraded transmission packages. The advantage of having a superior professionally built transmission (tested and ready to bolt in) delivered to you is definitely worthy of consideration.
Front Driveshaft to Transmission Pan Clearance
For the front driveshaft to clear the relatively wide 4L60E pan, the following installation steps are required:
- The engine must be installed offset to the driver's side as discussed on this page and in the instructions.
- The installer must use the factory 1-1/4" front driveshaft diameter.
- The transfer case front output yoke and corresponding driveshaft yoke must be the factory, low-profile style.
- The front axle should not be narrower than factory
There will be some situations where the front pan will interfere, despite these efforts, most commonly on the last two years of the CJ's production run. For these installations, a notched front pan is available.
Strength Comparison of 27 vs 23 Spline Versions
The 27 and 23 spline shaft sizes are quite comparable in minor diameter (the diameter of the shaft at the root of the splines) and therefore, strength. Diameters are very close and the finer 27 spline vs the coarser 23 spline has shown no significant strength variation. The 300M material used in production of the Novak shaft is of a superior strength both in PSI yield and torsional resistance - which is exactly the type of load these shafts see. Aside from that, fundamental design strengths are comparable.
GM 27 spline and Jeep / Dodge 23 spline shafts have a history of great strength in factory applications and Jeep aftermarket set-ups.
Output Shaft Strength
We’re avoiding the problem of a broken shaft like this one by going through the trouble and expense of making our output shafts from a solid bar of exceptionally strong 300M alloy steel, instead of lower grade alloys or friction welding salvage GM shafts. A second, sometimes less obvious but pernicious problem is the issue of warpage during friction welding and heat treating - which cannot be corrected when the shaft journals are already ground and worn at or below factory specifications. Novak shafts receive a final grind of bearing journals after the heat treat process to ensure the ultimate finish. The Novak shaft is produced to factory specifications with stress risers removed. Our 4-axis CNC cut of spiral gear, oil feed passages and other features are no small tasks. This attention to detail, maximized strength through design and material along with precise tolerances provide the ultimate parts for your project.
Jeep New Process 208, 219, 228 & 229 Transfer Cases
We've been known to recommend replacing the older style FSJ New Process transfer cases (especially the troublesome 219, 228 and 229) with a newer, more modern version such as the part-time 231J with HD SYE kit installed and upgrades as appropriate.
However, if your transfer case is in good condition, then move forward with the conversion.
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 strong transmissions native to 1/2 ton truck applications. Full Size Jeeps such as Wagoneers, J-Trucks, etc. are conversion candidates for them. There are numerous upgrades available for the 4L60E should stock strength come into question.
Engines
Any engine that can be made to work with the 4L60E will work with this adapter. All of the above mentioned native engines along with others that can be adapted via a front adapter (such as our 437 series kits) open up numerous possibilities.
Keep in mind that the 4L60E transmissions are electronically controlled and as such a non-native engine will require a controller.
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