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CJ-2A Driveshaft Upgrade & Rebuild

Posted in How To: Transmission Drivetrain on April 16, 2018
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It would have been so easy to toss a few 1310 U-joints onto the old front and rear driveshafts of our ’46 CJ-A build, rattle-can them with black spray paint, and call it a day. However, that wasn’t going to be the case for us. It turned out that the previous owner had swapped to a different-style driveshaft that eliminated the stock transfer case flange. Wanting our rig to be as original as possible, we reverted back to the factory-style transfer case flange for a stock emergency brake setup. That meant we needed a new and longer rear driveshaft.

With the need for a new and stouter rear driveshaft established, and a reconditioning/rebuild of the front shaft needed to finish off the CJ-2A drivetrain, we headed over to JE Reel Driveline in Pomona, California. The company has been doing high-end driveshaft work for decades, and Jim Reel’s shop is one of the go-to spots for serious off-roaders looking for drivetrain performance replacements and upgrades. Follow along as we give you a detailed look at how it all went together, and how your classic Jeep project can benefit from JE Reel know-how.

These were likely the original front and rear driveshafts, and they were definitely in need of some attention. Notice the old rear shaft has a sketchy weld in the center where it was shortened for the previous owner’s transfer case flange swap. Reel suggested we go with their new HD rear option to avoid any potential issues.
Even though both shafts would not move freely from years of inactivity, the front shaft splines were in surprisingly good condition upon inspection and made our decision easy to simply rebuild it.
Cleaning the front yoke started with soaking it in a degreaser solution for a while and then brushing the internal splines clean.
After removing the clips, the old 1310 U-joints were removed from the front driveshaft. What you see is us gripping it in a vise. What you don’t see is the hammering (carefully, of course) and prying that went on to get everything loosened from its grip on the shaft.
A wire wheel was used to remove all the loose dirt debris and surface rust from the front shaft. The entire shaft was wire-wheeled, which really helped prep the shaft for a nice paintjob later on.
The correct grease seal and retainer for our stock front driveshaft was on the shelf at JE Reel Driveline, making this job go even quicker.
Once the front shaft splines were coated with plenty of new grease, the seal and retainer were set in place.
Adding a bit of extra high-quality grease just before installing these 1310 U-joints onto the yokes will help them live a longer life under the Jeep CJ-2A.
Once the front shaft was complete with U-joints, it was moved over to a driveline-balancing machine. As a fitting testament to how things used to be built, the front shaft had no vibration at all, and no weights were added, even after years of off-road use.
Our JE Reel Heavy Duty rear driveshaft was created on the spot to our specs. The first step was to measure the length of tube needed to properly connect the two ends of the new driveshaft to its opposing yokes, while maintaining the correct amount of spline depth play during suspension movement. Ours ended up being roughly the center of the driveshaft’s travel and will be fine for this stock application.
Once the new centerpiece of tubing was cut to the needed length, deburred, and set into place, the shaft was then moved to the same balancing machine that also acts as the welding station. It’s difficult to read the gauge in the photo, but the shaft is slowly rotated and lightly tapped to get the least amount of runout for better balance prior to welding.
Now that’s a clean bead. With a welding gun set into position on the balancing machine, the shaft was slowly rotated as a precise weld joined the tube and yoke together.
As soon as the driveshafts came off the welder, they were immediately cooled with running water.
The completed rear driveshaft was now ready for balancing. Its precision set up using a dial indicator prior to welding meant the new driveshaft did not require any weights to keep it rotating smoothly.
Once the final rear yoke was attached and both complete driveshafts were ready for installation, they were wiped down with paint prep to remove any loose debris or grease and then painted.
With paint dry now, the new heavy-duty rear shaft was muscled up between the rear axle yoke and transfer case rear output flange, and a bolt and nut were started hand-tight on the output flange. This temporarily secured the shaft’s front end and made it easier to install the rear shaft to the rear axle using our reconditioned U-bolts with new lock washers.
Lastly, we returned to the rear output to finish the job. Grade 8 bolts are used and come in from the backside of the transfer case and stock e-brake drum. If this is the first reassembly after a transfer case rebuild, make sure to torque the rear large castle nut on the output shaft and put in the necessary cotter pin.


JE Reel Driveline Specialists

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