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Big lift, big tires, big wheeling trips…. you’ve now embraced Jeep life in a BIG way and you are also starting to find parts that are not holding up to all this BIG action. Driveshafts are one of those items that take a lot of abuse, especially if you are running a tall lift.
The driveshafts in the Jeep JL, like the previous model JK, use CVs at both ends on the rear driveshaft and at the transfer case end of the front driveshaft. They are a wear item and a weak point in your Jeep’s drivetrain. As you start to lift a Jeep, the CVs are operating at a steeper angle, which will cause the rubber boot to tear, allow water and debris in, causing wear, then vibrations and ultimately failure.
In the JKs, it was lifts taller than 3″s and 50-70,000 miles before it started happening. For the JL, typically driveshafts start to become a requirement at or past a 3.5" lift or if your shocks extend longer than 28". However, its never a bad idea to upgrade to heavy-duty driveshafts even if you're running less than 3.5" of lift!
The CVs in the Wrangler JLs and JT's have a new, slightly larger CV, but they are still just a simple CV with a rubber boot, which will see the same problems as the older JK CVs.
The CV on the left is from a JL with 15K miles on it. The JK CV on the right was ran with a lift and had around 80K miles on it. The boot was severely thrashed, the CV was packed with dirt and it had worn out enough to cause a serious vibration while driving down the road.
Another problem area is the stock JL (and JK) driveshaft tubes. They are a large diameter and have thin walls like a soda can which one good hit on a rock or a ledge could throw it out of balance causing vibrations. A real big hit could cause instant destruction of the shaft, sometimes severe enough to even take the transfer case out with it.
Now are we saying that CVs are junk?
Not at all!…. In a stock-ish JL (and JK) that is mostly used for on-road driving, the CVs are plenty strong and will have a long, smooth spinning life. It’s when you start adding big lift and longer travel suspension that the CV become a liability and it’s due to running them at higher angles than they designed for.
HD Replacement Driveshafts For the JL:
So if CVs are a problem, what should you do? Swap out those wimpy stock CV driveshafts for some heavy-duty driveshafts from Adams Driveshafts. The Adams Driveshafts use a smaller diameter, thicker tube that give a little more ground clearance and will take more trail abuse than the thin wall OE units. They also use u-joints in place of the CVs. Properly sized u-joints can take more angularity and will give longer life in a lifted Jeep that is seeing a lot of off-road use. The Adams Driveshafts are also serviceable and can be rebuilt down the road as they start to see wear.
Adams 1350 Front Driveshaft:
Big and burly is the best way to describe the 1350 Double Cardan Joint on the transfer case end of the Adam’s Driveshaft. The double cardan joint splits the amount of angle the u-joint has to run at, making it a great solution for running in a lifted Jeep that has higher driveshaft angles.
Adams 1350 Rear Driveshaft:
Another burly 1350 double cardan joint on the rear driveshaft helps split those angles and allow more lift and more travel than a single u-joint.
A single 1350 u-joint on the opposite end of the shaft to help keep the D.C. joint stable. What’s So Special About A 1350 U-Joint?
SIZE….. The 1350 joint is quite a bit larger than the commonly used 1310 u-joint. It has larger trunnions, larger caps and a larger spread between the caps. These combine to give us a stronger joint especially at angles.
Tools Needed:
45IP Bit
5/8″, 15mm, 32mm sockets
8mm – 12 point wrench
9/16″ wrench
Air Impact Gun
Socket Extensions
Gear/Bearing Puller
Soft Blow Hammer
Hard Face Hammer
Pry Bar
Removing the OE Rear Driveshaft:
First step is to make sure you have a 45IP bit (aka Torx Plus 45). The factory front and rear driveshafts are held in with bolts that have the high torque rated 45IP drive slot. Do not try to use a T45 Torx bit.
Introduced in 1990, Torx Plus is a higher torque replacement for the original Torx bit. The lobes are more square to allow for higher torque and to minimize wear. The name is shortened to IP (Internal Plus).
Using that 45IP bit, remove the eight driveshaft bolts holding the CV to the rear axle.
To get the factory CV loose from the cupped flange yoke, set one hammer against the side of the CV at a slight angle, then give it a couple sharp raps with another hammer. Spin the driveshaft 180° and repeat.
Once you have a little gap, work a pry bar in underneath the CV and work it out of the cupped flange yoke.
Remove the driveshaft bolts at the transfer case flange. Rotate the driveshaft as needed to get at the bolts.
Remove the OE rear driveshaft from the JL and set aside.
Use a 32mm socket to remove the rear yoke nut from the transfer case. A high-torque air gun will remove the nut pretty easily.
Then use a gear/bearing puller to remove the yoke from the JL transfer case. It’s on there tight, a puller make quick work of it.
The OE yoke uses a thick o-ring to help keep oil from seeping out around the splines. Unfortunately the new flange does not have the provision to accept the o-ring, so we do an old trick that works exceptionally well….
Add a little black RTV around the splines of the Adam’s Driveshaft. This will help keep the hot oil from wicking past the splines.
Use some assembly lube or other lightweight lubricant to lube the seal surface of the new transfer case yoke.
Install the rear transfer case yoke onto the output shaft, tap it into place if needed. Loctite the yoke nut and run it down tight. We used a 100 ft-lb. torque stick to get us close and then used a torque wrench to get to the final 160 ft-lbs.
Moving to the rear axle, use an inch-lbs. wrench to check the rotational torque on the rear pinion and write that measurement down. This measurement is crucial for the reassembly process!
Use that same 32mm socket on a good high-torque rattle gun to remove the rear pinion nut.
Then that handy gear puller to pull the stock pinion flange.
Lubricate the seal surface on the Adam’s Driveshaft pinion yoke and spread it around. You can use gear oil or any other light oil or assembly lube. We’ve used Lubriplate 105 assembly grease for years with great success.
Line the splines up and tap the new yoke into place with a soft blow hammer.
Add it little red Loctite to the yoke nut and tighten the pinion nut until snug.
Check the pinion preload, then tighten the nut some more. Rinse and repeat until you reach the same amount of your “before” preload measurement. If you go past, you cannot back it off, so be careful as you go along. ***DO NOT over tighten or you could have premature bearing failure.***
Installing the rear Adam’s 1350 Driveshaft in the rear of the JL:
Apply some Loctite to the supplied flange bolts.
Install the new 1350 rear Adam’s Driveshaft with the double Cardan Joint up against the transfer case. Use a 5/8″ socket and torque them to 80 ft.-lbs.
Remove the black tape holding the u-joints caps onto the u-joint trunnions and push the driveshaft into the rear yoke.
You may find the driveshaft needs to be compressed a little to get it into the rear yoke. Use a big soft blow hammer and give it a few love taps to get it to compress. Be careful not to lose the u-joint caps!
Add a little Loctite to the threads of the supplied u-bolts, install them over the u-joint caps, then use a 9/16″ wrench to tighten the nuts down snug, final torque to 24 ft-lbs.
Removing JL Front Driveshaft:
Start by removing the bolts holding the front driveshaft at the front pinion yoke. Use a 15mm socket.
It’s a little tougher up at the transfer case end, reach up and in with an extension to get the 45IP bit into the bolt heads.
To separate the front driveshaft from the flange, use a hammer and give it a good solid wack. If using a hard face hammer, make sure you hit the driveshaft flange square to avoid from damaging it. Better yet, use a large soft blow hammer to reduce the chance of damaging it.
Pull the front driveshaft out and set aside.
Reach back up to the front transfer case yoke and remove the nut. It is quite tight up in there, take your time and you’ll get it.
The gear puller comes back out and just like the rear, pull the front transfer case yoke.
Prep the Adams Driveshaft front transfer case yoke the same as you did the rears, a little RTV on the splines, some assembly lube on the seal surface of the yoke and a little Loctite in the threads of the nut.
We again used the handy Torque Stick to get the yoke nut to 100 ft-lbs. then torque it to the final of 160 ft-lbs.
Loctite the supplied front double cardan bolts and bolt up the transfer case side of the driveshaft. These bolts are 8mm – 12 point bolts and it is quite tight up there, use an 8mm – 12 point wrench and get them tight.
Slide the new Adam’s 1350 front driveshaft into the vehicle and seat the double Cardan Joint up against the new transfer case yoke and the other end against the front axle pinion flange. The space around the front shaft at the t-case is tight. We ended up having to drop the Artec Aluminum Belly Pan to get a wrench in on the driveshaft bolts and get them tight enough.
