JL T-case??

1

13_gecko_rubi

New member
8wr_zj said:
The new system on the JL is almost identical to the system used on the newer 2500/3500 RAM trucks. There are companies that already make solid axle shafts that will eliminate the FAD on the 2500/3500. I think this will become a standard MOD for anyone that beats on the JL on the trail. Basically the FAD function is to disconnect the right hand side axle shaft from the rest of the drive train. This allows the left axle shaft and spider gears spin in the housing not the ring and pinion or the front driveshaft. I believe the FAD helps with MPG numbers on the JL.

Here is a link on cumminsforum.com that has more information on the ram trucks.

http://www.cumminsforum.com/forum/2013-general-discussion/2034394-front-axle-disconnect.html
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Correct. But many folks don't bother on the RAM and it hasn't been an issue. People worry based on the old vacuum systems that had issues. The newer electronic ones won't. I know Cooper has run Ultimate Adventure and every trail in the West with his RAM on 40s with stock axle shafts including FAD.

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JTCO

JTCO

Meme King
13_gecko_rubi said:
You can try the fad electronics easily. Otis a dumb device with a power feed and a return signal like the lockers, it isnt a smart device like the sway bar.

It is hard to explain what/why you need to make a small change via writing. There is a synchro/interlock in tcase to spin up the front driveshaft to match rear before allowing tcase into 4wd.

A good way to see what I mean is if u have a jk with front hubs. Unlock the hubs and go cruising down road. The front driveshaft won't be spinning, try to yank your tcase in 4wd and you will hear a horrible grinding noise as the rear of the tcase is spinning at road speed and the front is sitting still. This is why it's there as with fad the front driveshaft isn't spinning and needs to get up to speed before locking the tcase.

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This makes perfect sense. Thanks. And I'm sure aftermarket will figure out some way around it.

So question.....if you wanted to shift into 4HI with this system (and have an aftermarket front axle), couldn't you just come to a complete stop, shift the new tcase like normal, and avoid all of the grinding symptoms?
 

1

13_gecko_rubi

New member
WJCO said:
This makes perfect sense. Thanks. And I'm sure aftermarket will figure out some way around it.

So question.....if you wanted to shift into 4HI with this system (and have an aftermarket front axle), couldn't you just come to a complete stop, shift the new tcase like normal, and avoid all of the grinding symptoms?
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You would think so. But if the teeth aren't meshed perfectly the interlock won't let you engage it and the synchro isn't strong enough to spin the whole front end. This is why you need to modify it. I don't think it will be a huge deal if you are mechanically inclined. Definitely easier than a SYE imo.

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wayoflife

wayoflife

Administrator
Staff member
13_gecko_rubi said:
You can try the fad electronics easily. Otis a dumb device with a power feed and a return signal like the lockers, it isnt a smart device like the sway bar.

It is hard to explain what/why you need to make a small change via writing. There is a synchro/interlock in tcase to spin up the front driveshaft to match rear before allowing tcase into 4wd.

A good way to see what I mean is if u have a jk with front hubs. Unlock the hubs and go cruising down road. The front driveshaft won't be spinning, try to yank your tcase in 4wd and you will hear a horrible grinding noise as the rear of the tcase is spinning at road speed and the front is sitting still. This is why it's there as with fad the front driveshaft isn't spinning and needs to get up to speed before locking the tcase.

Sent via....
Click to expand...

Ah, got it. Makes total sense now and kind of a bummer. Oh well, for most people, this won't be an issue. For me, I guess it's something I'll have to do a write-up on :crazyeyes:

13_gecko_rubi said:
You would think so. But if the teeth aren't meshed perfectly the interlock won't let you engage it and the synchro isn't strong enough to spin the whole front end. This is why you need to modify it. I don't think it will be a huge deal if you are mechanically inclined. Definitely easier than a SYE imo.

Sent via....
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You mean there aren't any crazy snap rings to deal with? :crazyeyes:
 

Piginajeep

Piginajeep

Moderator
wayoflife said:
Ah, got it. Makes total sense now and kind of a bummer. Oh well, for most people, this won't be an issue. For me, I guess it's something I'll have to do a write-up on :crazyeyes:



You mean there aren't any crazy snap rings to deal with? :crazyeyes:
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Lol, if it’s easier than an SYE, I don’t see the big deal unless the parts are stupid expensive. I did the SYE with no mechanical experience at all.


2012 JK8
1958 FC170 (Jeep Forward Control)
 

wayoflife

wayoflife

Administrator
Staff member
Piginajeep said:
Lol, if it’s easier than an SYE, I don’t see the big deal unless the parts are stupid expensive. I did the SYE with no mechanical experience at all.


2012 JK8
1958 FC170 (Jeep Forward Control)
Click to expand...

Well yeah, you used my super detailed write-up :crazyeyes: :D
 

1

13_gecko_rubi

New member
wayoflife said:
Ah, got it. Makes total sense now and kind of a bummer. Oh well, for most people, this won't be an issue. For me, I guess it's something I'll have to do a write-up on :crazyeyes:



You mean there aren't any crazy snap rings to deal with? :crazyeyes:
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Never said there weren't any snap rings to deal with :)

You shouldn't have to buy any parts, just remove something.

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wayoflife

wayoflife

Administrator
Staff member
13_gecko_rubi said:
Never said there weren't any snap rings to deal with :)

You shouldn't have to buy any parts, just remove something.

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:cheesy: I like to call them Jesus Rings, as in... "Jesus! This thing is a pain!!" or "Jesus!! Where did it go?!" :eek: :crazyeyes:
 

Strike Force Zebra

Strike Force Zebra

Supporting Advertiser
In the 4wheeler write up, they noted a workaround that could be as simple as reprogramming the computer.

“Sadly, front-axle disconnect (FAD) returns to help boost fuel-economy, albeit in a more durable electric form, not the troublesome vacuum system of the past. Thankfully, Jeep engineers have JL owners intent on replacing their front axle covered with a software workaround that allows the FAD to be disabled by the dealer. These same dealer tools can also reprogram popular parameter changes required by enthusiasts, such as gear ratios and tire size.”

We will see....


Sent from my iPhone using JL Wrangler Jeep Forum mobile app
 

wayoflife

wayoflife

Administrator
Staff member
Strike Force Zebra said:
In the 4wheeler write up, they noted a workaround that could be as simple as reprogramming the computer.

“Sadly, front-axle disconnect (FAD) returns to help boost fuel-economy, albeit in a more durable electric form, not the troublesome vacuum system of the past. Thankfully, Jeep engineers have JL owners intent on replacing their front axle covered with a software workaround that allows the FAD to be disabled by the dealer. These same dealer tools can also reprogram popular parameter changes required by enthusiasts, such as gear ratios and tire size.”

We will see....


Sent from my iPhone using JL Wrangler Jeep Forum mobile app
Click to expand...

Sure would be nice if they're right :crazyeyes:
 

RMC2

RMC2

Member
I saw this on Facebook too, and was thinking what the heck.

Then I read this and think, Hmmm.

Then I have nightmares about the vacuum fad on my truck.
 

8

8wr_zj

New member
13_gecko_rubi said:
Correct. But many folks don't bother on the RAM and it hasn't been an issue. People worry based on the old vacuum systems that had issues. The newer electronic ones won't. I know Cooper has run Ultimate Adventure and every trail in the West with his RAM on 40s with stock axle shafts including FAD.

Sent via....
Click to expand...

There is no issue in strength of the axle shaft those things are beefy or the slide that engages both shafts. My first hand experience is with the FAD system in itself. My brother is a manager for a construction crew. First I have had to go pull him out because the FAD would not engage(replaced under warranty no service 4wd message). The front drive shaft was spinning but no power to the front wheels on both occasions. Second time he replaced his brake pads and afterwards got an abs light on the test drive. He was going to see if the sensor was frayed,or pulled a pin connector or maybe he broke it. He would check it the following day it was a short work day anyways. Well he needed 4wd to remove a stuck trailer no go gave a service 4wd message. He had messed up an abs sensor on the left front side. I had to go pull him out and the stuck trailer. If I have a 4wd I want it to work when I need it and not by the grace of the computer. Also he ordered his truck with a manual 4wd shifter on the floor. he "didn't want the motor to fail and not let him have 4wd" oops should have gotten a FAD delete. Only thing we can think is we had a lot of water this past year and he drove through water that was 1-2 feet deep multiple times to reach his house. hopefully jeep has done a better job of getting the FAD bulletproof. This is why my truck has manual locking hubs as a backup if the vacuum lock system does not work.
 

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