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Vintage Jeep Driveshaft Upgrade

Posted in How To: Transmission Drivetrain on September 26, 2017
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Off-roading is a whole heap of fun, and it’s also a whole heap of extra stress and additional loading on your Jeep. The first common upgrade is to get high traction tires, maybe even a couple sizes larger than stock. That leads to better axleshafts or beefier axle assemblies. It’s all in the name of running even larger tires and driving your Jeep over more difficult obstacles.

With all of that going on you have likely overlooked one item: the propeller shaft—and we aren’t talking about boats. It’s that steel tube with wiggly ends delivering torque to the axles. Driveshaft upgrades are often the last thing we think to do when outfitting an older Jeep. Luckily, the driveshaft experts at Tom Wood’s Custom Drive Shafts have the knowledge and parts to help even the older and rustier side of Jeeping.

If you own a Willys or Kaiser-era Jeep, it likely has a 1310-sized universal joint on the rear driveshaft that is still common today in many 4x4s, but the front driveshafts use the smaller-yet 1210 universal joint. These 1210 U-joints are still available, but spares might be hard to find when you’re in Timbuktu, and it’s still a 1210 and not as strong as the factory rear 1310 driveshaft.

Our choice was to not go crazy on a rig that in all probability, and baring an engine swap, tops out at about 150 hp. Upgrading to a stronger and more common 1310 U-joint front driveshaft for any Jeep equipped with a Dana 25 or Dana 27 front axle sounded like a darn good idea.

Our 1967 Jeepster Commando was suffering from factory 1210 U-joint syndrome. We checked in with Tom Wood’s Custom Drive Shafts for advice on the most logical upgrade that would get the job done well without emptying our wallet. Here’s what we came up with.
The stock front driveshaft on this Jeepster was a two-piece design with a carrier bearing to help the driveshaft clear the exhaust. A previous owner had eliminated the awkward two-piece design, with the help of some long tube headers on the stock Buick 225 Dauntless V-6, and installed a simple one-piece driveshaft. The one-piece was too short and was fully extended at ride height leaving no room to allow for suspension movement. The slip joint could have separated on the trail.
The size difference is considerable between the new 1310 Gold Seal Universal joint installed by Tom Wood’s versus the stock 1210 Spicer U-joint. All of the early Jeeps including the MB, CJ-2A, CJ-3A, CJ-3B, Kaiser CJ-5, and CJ-6 are equipped with a Dana 25 or Dana 27 front axle and either a Dana 18 or Dana 20 transfer case. These vehicles can all benefit from upgrading to a stronger 1310 universal joint front driveshaft.
The transfer case yoke is the easy part. Our Jeepster was equipped with a Dana 20 transfer case. All that had to be done was install a Dana 20 front output yoke that was intended for a 1310 U-joint. Easy, he said. If you are working with an older CJ-5 or Willys Jeep with a Dana 18 transfer case, then the job and the parts are the same. Since the Dana 18 and Dana 20 are so similar, a 1310 Dana 20 front yoke bolts in place. No puller was needed to remove the old yoke. You will need to drain the transfer case first to avoid a mess.
The yoke on the front axle must be changed out to a yoke from a Dana 30, which Tom Wood’s provides in the package. It has the same spline count to fit the Dana 27 or Dana 25 pinion. All-new Spicer U-bolt hardware was included with the new driveshaft.
The old yoke was removed from the pinion with the help of a puller. Sometimes they get stubborn after being bolted down for 50 years. Be prepared with an oil pan; the differential may have some oil left in it, even after draining.
The front axle’s new yoke (right) is slightly shorter overall than the stock Dana 27 yoke (left). If this issue is not addressed, the new yoke will not properly hold the outer pinion bearing into place when the pinion nut is seated. No worries, Tom Wood’s Custom Drive Shafts machines custom bushings to compensate so that proper pre-load force is applied to the bearings.
Comparing the faces of the stock 1210 yoke versus the new 1310 yoke makes it easy to see the difference in size. Size really does matter when it comes to the strength and reliability of your driveshaft components.
The new driveshaft assembly from Tom Wood’s is made from better-than-stock materials. It features all-new components coupled with a high-strength 0.180-inch wall DOM tube that will put up with some serious abuse. Our Jeepster may be relatively stock, but it sees its fair share of obstacles out on the trail.
The front yoke was installed on the Dana 27 along with a new Yukon pinion seal. The Yukon seal is a newer double-lip design that has a slightly different offset than the factory Dana 27 single-lip pinion seal. We found that the factory replacement pinion seal from the auto parts store did not properly seal around the new 1310 yoke and custom-machined spacer, and we observed a leak almost immediately. The Yukon seal for a Dana 27 worked perfectly.
Torque the pinion nut to spec. Always consult a manual for the proper specifications. A friend with their foot on the brake and the hubs locked in is enough to keep things from turning so you can properly torque the axle pinion nut. To torque down the transfer case output yoke nut, simply put the transmission and transfer case in gear.
The Dana 20 1310 yoke from Tom Wood’s bolted right into place without any issues. The original seal was working perfectly and did not need to be changed. If your old seal was leaking beforehand or looks to be in bad shape, then this is a perfect time for a fresh one. Don’t forget to refill your T-case with fresh gear oil after the new yoke is in place and torqued to spec.
Now we could bolt in the Tom Wood’s Custom Drive Shafts 1310 driveshaft. If you’ve never done this, it’s difficult to imagine the balancing act that goes on for a few minutes underneath the rig with a heavy driveshaft in one hand and a wrench and parts in the other. Four new Spicer U-bolts were included with the new Gold Series 1310 U-joints. We made sure that the joints were properly seated in the yokes before cranking down the U-bolts. Don’t overtighten these bolts though, as too much stress on the U-joint caps could distort them and lead to premature failure.
That’s it. Not only do we now have a much stronger and reliable driveshaft, but we have also created common components across the Jeep. A spare 1310 U-joint in our toolbox will work on the front or rear driveshaft of the Jeep now. We will also be able to easily find U-joint parts on the shelf at any auto parts store. Time to hit the trail!

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