Ok so i recently swapped out my 3.55 gears in my cherokee for some 4.11's. This is what is said on the box; Some slight sound may be detected under light load, this is considered normal and is in no way detrimental to the rear end. Doesn't this seem a little weird to anyone??

 

If they are set up right you shouldn't hear them. If they roar they will wear prematurely and cause bearing wear as well.

 

ok i understand that but you can barley hear it. once the music is on you dont even notice it. and like i said the box said it was expected...damn im torn both ways

 

I know a guy who has worked on the line in the Dana plant in Ft. Wayne Indiana since the 70's. He told me that unless you get the gears lined up perfectly you will always have some noise coming from the rear axle. There is an acceptable margin for error, and if you are off just enough you can have premature wear, and bearing failure. That being said, if they are installed properly you shouldn't have much noise. Did you install the gears yourself or did you have it done by a shop? The shop should warranty their work, and if thats the case I wouldn't worry about it too much unless the noise gets louder.

In my experience I've been pretty lucking when swapping out gears and ending up with little to no noise. I light hum is not uncommon though. After all its a jeep, not a Cadillac

 

Straight Lucas Oil in the diffs and transfer case will quiet any slight noise you have. I've done this in all the mustangs I've had (no insulation so there's always noise), and all the 4X4's. Hasn't given me any problems yet. That and if you do a posi there is no need for the additive.

 

Now I have to do a search on Lucas Oil.... is that like a universal rear end oil? I just got my Jeep and am about to look at (pull) the diff covers, but am still wondering exactly what to put in as depending on the rear end/tranny combos or whatever there's like 3 different oil/additive combinations. Well, you gave me something to think about. Time to do a forum search LOL

 

Don't know if you've done it yet or not, but if you look at a Lucas Oil bottle it says the ratios of Lucas to gear oil to use or to just pump it full of Lucas. Positive thing is if you have a posi axle you don't need the special additive if you use straight Lucas.

 

I ran Lucas in my 98 when I had my locker installed in it. It ran just fine but in all honesty I couldnt tell a difference between running lucas and Valvoline syntec full synthetic 75W-90. Lucas is a great brand and I recommend it to anyone, its just really expensive.