Full-time four-wheel-drive driveline vibration with lift

[guruman]

Also.... you might just try a different aftermarket drive shaft solution.

My JK was running the Metalcloak 5.5 inch lift, which is about as much lift as you could get without some serious fabrication.

I ran an Adams 1350 shafts without issue for tens of thousands of miles, even with all of that lift.


And... you CAN clock your existing axle.. essentially takeout all apart, cut the tubes inboard of the knuckle, and rotate and re-weld to get a better caster/pinion angle. That's really the only no-compromise option.

 

[guruman]

And... just to confirm my own thoughts I found this in the 2023 owners manual... this tells me the front driveshaft is spinning (from the friction passed to it from the non-disconnected axle shaft through the diff), even on the FAD equipped axles.

It's really kind of a shame they added the FAD to get a tiny bit of MPG. Seems to me a set of proper locking hubs and true 2wd would have yielded much better MPG gains, at the cost of needing to actually stop to switch into 4wd. THE MPG difference in every old Scout/Bronco/Blazer I've ever owned was pretty dramatic.

 

[stumblinhorse]

The aftermarket is going to solve this. Especially since 2024 JLs with 4H auto will all be the same 392 setup…

 

[Cali392JL]

I left out one critical point. I have the 392 which has full-time four-wheel-drive, but I also have a Tazer, which allows me to disconnect the front drive shaft at the transfer case. If I could disconnect the axles, I think I would be stopping the drive shaft from spinning.

 

[EBYCREEK]

I've installed 2 of the Metalcloak 3.5 inch game changer 392 lifts along with the Metalcloak front driveshafts and have no vibration up to 99 mph. Currentley running 6.3 - 6.4 degree's caster.

 

[7.62x392]

I left out one critical point. I have the 392 which has full-time four-wheel-drive, but I also have a Tazer, which allows me to disconnect the front drive shaft at the transfer case. If I could disconnect the axles, I think I would be stopping the drive shaft from spinning.

Ask this guy, he’s the first I’ve seen successfully convert a factory Rubicon 392 to an Atlas. I was messing around on the Advance Adapters website last week and a 2 speed case for the 392 plus the adapter and all other add on parts needed is about $5K.

392 Atlas transfer case install

Advance Adapters FINALLY has the correct parts to make this work (even if they do scab 3 adapters together 🙄). I’ll save all the drama for another day, but the main case and some of the parts have been sitting on my shop floor since mid-December. Today the rest of the pieces showed up, so I left...

www.jlwranglerforums.com

 

[84jeepjohn]

So I just had my wrangler back to Cloakworks, who is affiliated with Metalcloak. They are an excellent shop with more experience with the metalcloak system than anyone on the planet. They replaced my 1310 front driveshaft and there was still vibration above 70 miles an hour. They decreased caster to 4 1/2° and still vibration. Lastly, they replaced the U joint 1310 driveshaft with a stock driveshaft and the vibration is gone. This is not a permanent solution as the stock driveshaft will not work well in Xtreme off Roading conditions. They have an idea of that possibly the yoke on the transfer case side is machine incorrectly and causing problems. They are sending both driveshafts and the yolk back to the driveline shop to have evaluated.

This is proving to be a pretty elusive problem. Shame on Jeep for not allowing the front axle to be disconnected.

Jeep/Dana could have fixed this issue with rotating the pinion up/or more caster direct from the factory, but nope they have left them the same since 2018.

 

[bluej]

And... you CAN clock your existing axle.. essentially takeout all apart, cut the tubes inboard of the knuckle, and rotate and re-weld to get a better caster/pinion angle. That's really the only no-compromise option.

guruman say's it all.

remember you only have a dana 44 rear end, you spend all this money to disconnect the front axle to get rid of driveline vibration and now you're putting all 470hp/470 foot pounds of torque to that rearend. by reclocking your front axle and keeping everything else the same your jeep is back to where it was before you lifted it.

 

[LTZ470]

Front Shaft will still be turning (Front Wheels will continue to turn it), the only way you could stop it is with a Transfer Case change or Lock Out Hubs, I don't think they even make Lock Out Hubs for the JL Models....

 

[hardhat]

Steering Solutions - Exact Center - Roadmaster Inc.

www.roadmasterinc.com

Consider this. It is a gas pressurized stabilizer that works in both directions. It holds the wheels straight ahead and resists turning in either direction with 100 lbs (you can buy different strengths). Caster is what gives you the on center feel. With this device you can set your caster at whatever and it will still return the wheel to center. Thus you can ignore caster and set your pinion angle where you want it. This might be easier and cheaper than reclocking the axles. I have one on my 392 which is stock and it gives a nice on center feel and keeps jeep from blowing all over the road in winds.
You have to adjust it to get it just right or it will be constantly pulling to left or right, but once you get it set dead straight, it is nice. 22mm wrench is all it takes to adjust. I left one in the garage and made tiny tweaks over the course of a few days to get it just right.

 

[guruman]

Steering Solutions - Exact Center - Roadmaster Inc.

www.roadmasterinc.com

Consider this. It is a gas pressurized stabilizer that works in both directions. It holds the wheels straight ahead and resists turning in either direction with 100 lbs (you can buy different strengths). Caster is what gives you the on center feel. With this device you can set your caster at whatever and it will still return the wheel to center. Thus you can ignore caster and set your pinion angle where you want it. This might be easier and cheaper than reclocking the axles. I have one on my 392 which is stock and it gives a nice on center feel and keeps jeep from blowing all over the road in winds.
You have to adjust it to get it just right or it will be constantly pulling to left or right, but once you get it set dead straight, it is nice. 22mm wrench is all it takes to adjust. I left one in the garage and made tiny tweaks over the course of a few days to get it just right.

This is interesting.... didn't know anyone was making these. Back in the day somebody made a similar product with springs instead of being gas charged.

Speaking of the gas charged setup.... what will happen when (not if) one side of that thing loses its seal, depressurizes and you get 100 pounds of push from the other side?

I do take issue with the marketing wank though. Giving your RV "sports car like" handling , and "fights death wobble" are both kinda BS.

 

[LTZ470]

Steering Solutions - Exact Center - Roadmaster Inc.

www.roadmasterinc.com

Consider this. It is a gas pressurized stabilizer that works in both directions. It holds the wheels straight ahead and resists turning in either direction with 100 lbs (you can buy different strengths). Caster is what gives you the on center feel. With this device you can set your caster at whatever and it will still return the wheel to center. Thus you can ignore caster and set your pinion angle where you want it. This might be easier and cheaper than reclocking the axles. I have one on my 392 which is stock and it gives a nice on center feel and keeps jeep from blowing all over the road in winds.
You have to adjust it to get it just right or it will be constantly pulling to left or right, but once you get it set dead straight, it is nice. 22mm wrench is all it takes to adjust. I left one in the garage and made tiny tweaks over the course of a few days to get it just right.

Can you confirm it fits the Rubicon with sway bar disconnect?

 

[guruman]

The bottom line here is that this IS solvable without any magic. Lots and lots of Jeeps are running 3.5 inch lifts without issue. There shouldn't be anything special about the OPs setup. Swap in a 7k atlas and 20k axles to get the front driveline to stop turning if you want, but it's overkill for just 37s and mild wheeling.

The only thing I can think of at this point is that the front adjustable arms might be out of whack. Setting the 4 front arms up so that you have a desirable axle position, alignment and the recommended pinion angle (MC should be able to recommend a pinion angle), then adding a quality driveshaft made for this. I chose Adams, but there is Tom Woods and a dozen other good choices that just bolt in.

Thousands upon thousands of Jeeps are running like this.

 

[@WhiteBronze392]

I'm running the 3.5" 392 Metalcloak Game-Changer lift on my 2021 392 and have no vibration. I have installed this lift on 2 392's and neither one of us has any vibration. My caster is set at 6.4 degrees and I'm running the Metalcloak front driveshaft. The part that sucks is every oil change I have to remove my skid plates to be able to grease the front CV. I wish Teraflex would build a front Rzeppa driveshaft like they do for the JK's.
View attachment 20580

I am surprised none of the custom aftermarket driveshaft companies or some industrious owner hasn't had a custom one built for the 392

 

[EBYCREEK]

If we could talk Teraflex into making this driveshaft for the 392 if would fix out problems.

 

[EBYCREEK]

Can you confirm it fits the Rubicon with sway bar disconnect?

I've been running this on my 392 for 6 months, works great. And yes it fits with the sway bar disconnect.

 

[LTZ470]

I've been running this on my 392 for 6 months, works great. And yes it fits with the sway bar disconnect.

When I went to the site the topmost one said will not fit Rubicon with sway bar disconnect, so I guess the bottom one fits…

 

[EBYCREEK]

When I went to the site the topmost one said will not fit Rubicon with sway bar disconnect, so I guess the bottom one fits…

I run the Exact center on top and left the factory steering stabilizer where it was.

 

[7.62x392]

The bottom line here is that this IS solvable without any magic. Lots and lots of Jeeps are running 3.5 inch lifts without issue. There shouldn't be anything special about the OPs setup. Swap in a 7k atlas and 20k axles to get the front driveline to stop turning if you want, but it's overkill for just 37s and mild wheeling.

The only thing I can think of at this point is that the front adjustable arms might be out of whack. Setting the 4 front arms up so that you have a desirable axle position, alignment and the recommended pinion angle (MC should be able to recommend a pinion angle), then adding a quality driveshaft made for this. I chose Adams, but there is Tom Woods and a dozen other good choices that just bolt in.

Thousands upon thousands of Jeeps are running like this.

I wouldn’t say thousands of Jeeps are running a 3.5 inch lift with full Auto and no 2WD or FAD without issue. The front driveshaft always spinning on our 392s is what causes the vibrations. That is not the case with any other JL. I think someone said earlier here or in another thread the driveshaft is spinning on JLs even with the FAD but that is not true (see below video). Jeep really screwed us with this transfer case / no FAD combo.

 

[guruman]

I wouldn’t say thousands of Jeeps are running a 3.5 inch lift with full Auto and no 2WD or FAD without issue. The front driveshaft always spinning on our 392s is what causes the vibrations. That is not the case with any other JL. I think someone said earlier here or in another thread the driveshaft is spinning on JLs even with the FAD but that is not true (see below video). Jeep really screwed us with this transfer case / no FAD combo.

There's probably a dozen 392s on here doing it.

JKs have the same limitations with pinion and drive line angles. I've driven my 5.5 inch lifted JK for many many miles at speed in 4wd without vibration, again worse angles the a JL with 3.5 inches of lift.

And you may be right about the drive shaft not spinning, but I cannot get my head around how you could shift on-the-fly at speed, if it's not. It cannot be engaging the FAD as the axle shafts would be spinning in opposite directions. So how then does the 100 pounds of steel (transfer case, drive shaft, ring, pinion spider gears and one half of the axle) get from zero to highway speed in the amount of time it takes to move the lever from 2h to 4h?

This has always been the dirty little secret of shift-on-the-fly, all of the driveline had to be spinning all the time anyway. It's why some folks would swap in manual locking hubs, so that they could gain an extra 5 or so MPG when in 2h.