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After re-gear break in question...

prewdog4

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So, just had the JT regeared to 4.88. Forgive my noobness, but I’m not sure if the front axle (ring & pinion) actually turn for break in, or does it have to be in 4wd to break in the front gears? This is our first Jeep, always owned Chevy 4wd trucks with lock out hubs, so I’m not sure how the Jeep works??

Also, I’ve researched and looks like I should for sure drain the break in gear lube after 500 miles and add new, is this for sure? I just don’t understand why we never drain the gear lube and replace on a new vehicle, why is that? Are the gears different when the vehicle is new?

Thanks for any help you can give....
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From my understanding, the gears turn that’s why FCA put in the fad system for mpg reduces drag due to turning gears, looking in the owners manual for new vehicle break-in it doesn’t require 4 wheel drive to be engaged. I’d just follow the proper guidelines on Mileage and variable speed as specified by manufacture of your gears.
 

CWGrisw0ld

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My shop told me to drive in 4wd as much as possible and return after 500 miles to drain
 
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prewdog4

prewdog4

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Yeah, I was afraid of the different answers I was going to get...
Thanks, for the replies. We’ll see who else chimes in...
 

CerOf

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The R&P turns. The FAD disconnects the outer axle in the passenger side from the inner axle.
 

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So, just had the JT regeared to 4.88. Forgive my noobness, but I’m not sure if the front axle (ring & pinion) actually turn for break in, or does it have to be in 4wd to break in the front gears? This is our first Jeep, always owned Chevy 4wd trucks with lock out hubs, so I’m not sure how the Jeep works??

Also, I’ve researched and looks like I should for sure drain the break in gear lube after 500 miles and add new, is this for sure? I just don’t understand why we never drain the gear lube and replace on a new vehicle, why is that? Are the gears different when the vehicle is new?

Thanks for any help you can give....
1. Even though the front gears turn when you are in 2 wheel drive, they have no load. It is best to run 4 wheel drive high for some miles to help break them in. Find a dirt fire road that you can run for a while.
2. Yes, replace the lube. There are drain holes for both the front and back, so, you do not have to pull the diff. covers. If you have a Rubicon, we have heard that the lockers are sensitive to too much metal, so, make sure to change the lube.
3. The Factory uses (more expensive) Dana Spicer gears which are supposed to require less, or little, or no break in. Note: I did change gears also and used Dana Spicer 5:13s and the powdered metal on the magnetic drain plug was the same amount as when I change the diff oil with the stock 4:10 gears.
 

whiteglad

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The ring and pinion turn some with the axle disconnected. Mostly the side gear attached to the axle that is not disconnected will run around the spider gears if there is resistance on the pinion. It is a good idea to use 4H some, on dirt or snow, but not to the point of getting crow-hopping from the front axle universal joints (which happens with the wheels turned a lot, in fairly good traction and 4WD) or binding from getting too much traction when turning any (because the wheels want to turn at different speeds but the front to rear is locked). I agree to drain the lube after 200-1000 miles. That would be a good time to install stronger diff covers, I chose Motobilt for strength and moderate cost. Mobil 1 75-90 is one good lube.
 

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Make sure you heat cycle those puppies several times. My shop told me to hit up 4wd some just to get them turning. I drive into the neighborhood in 4H.

500 miles of random speed driving. Avoid huge hills. Depends on where you live. .....gear oil change.

Have a great time after that.
 

CerOf

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4-h doesn’t get the gears turning. going in 4wd just applies a load.
 

whiteglad

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The ring and pinion turn in 4H and 4Lo because the axle disconnect on the right axle is locked, the left axle is solid so both are attached to the wheels and turn with them. Thus, the carrier turns and that turns the ring which then turns the pinion. Now that would be the situation if the transfer case is not driving the pinion (i.e. if you could lock the axle disconnect separately with the transfer case in 2H or N) However, you locked the disconnect by putting the transfer case into 4wd, which activated the shift motor of the disconnect, so everything is turning and the engine is transmitting power to the tires.
 

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3 or 4 good hard launches locked in 4wd should do the trick well :devil:

jk jk, definitely don't do that.
 
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prewdog4

prewdog4

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Thanks for all the replies...I think I understand the system more now. Definitely not the simple lock outs from my past. Thanks again!
 

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So, just had the JT regeared to 4.88. Forgive my noobness, but I’m not sure if the front axle (ring & pinion) actually turn for break in, or does it have to be in 4wd to break in the front gears? This is our first Jeep, always owned Chevy 4wd trucks with lock out hubs, so I’m not sure how the Jeep works??

Also, I’ve researched and looks like I should for sure drain the break in gear lube after 500 miles and add new, is this for sure? I just don’t understand why we never drain the gear lube and replace on a new vehicle, why is that? Are the gears different when the vehicle is new?

Thanks for any help you can give....
Here is the break in process for my gears. (See link below) Changing the fluids is to get rid of any metal shavings etc from the break in process is my understanding. https://www.revolutiongear.com/ring_and_pinion_break_procedure
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