I'm picking up the heep tomorrow installed with fresh new 4.88s and a ford 8.8. Is there extra maintenance that needs to happen? Special oil or frequency of changing? My buddy read something on his JK forum about breaking them in properly. Is that with the xj too? They are Yukon gears. Thx

 

You'll need to change the diff fluid after about 500 miles. You have to baby it during the break in period (slow take offs, gradual breaking) and no long trips.

 

Is 150 miles a long trip? Gotta drive it home from Denver.

 

I would stop halfway and give the gear oil time to cool. And during the trip, I wouldn't take it over 55. That's just me though, I would baby it as much as possible

 

you'll be fine.
what they mean by babying it is for the drag racers, so they don't just install and hit the strip.

but as suggested, it wouldn't hurt to stop for lunch half way just to give it time to cool. but i'm sure you will be fine.

 

^
x2

I learned the hardway 2 days after my TJ was regeared I drove it 250 miles and beat on it wheeling all weekend on my way home the rear end seized up.

 

you dont need to baby it, just avoid prolonged heat.

if it was setup right, then there will be alot of friction and a ton of heat from the bearings breaking in and the gears meshing together. avoid cruising at highway speeds for longer than 30minutes at a time.


and at 500miles, replace the fluid

 

did either have a lsd? if so it will require a aditive

 

I replaced a R&P, and had to make a long drive the next morning. What I did was drive home about 20 minutes, drove to the store maybe 10 miles, then home and let it cool down over night. The next day I drove about 100 miles then pulled in for gas, grabbed a snack, took a leak, etc, then drove about 200 miles and repeated the gas, snack, leak, etc, the stops took about 15-20 minutes. I also stopped twice at rest stops for a few minutes. The trip was almost 700 miles and I took all day to make the trip, but I never had problems with the differential set up.