Differential question

GeoWillys

New member
I just got me 15 JK re-geared and am going through the breakin period which got me wondering. When you buy a brand new jeep no one tells you to do any kind of breakin and change your diff oil after 500 miles. So how is it new vehicles dont require you to do this? Plus how do the gears get broken in then?
 
I just got me 15 JK re-geared and am going through the breakin period which got me wondering. When you buy a brand new jeep no one tells you to do any kind of breakin and change your diff oil after 500 miles. So how is it new vehicles dont require you to do this? Plus how do the gears get broken in then?

It’s in the Manuel to maintain speeds under 55 to 65 for the first 350-500 miles depending on the vehicle. It does not say that you should swap the gear oil, it’s never a bad idea. Most people, including the sales staff never take time to read the actual manuals.


2015 JKUR AEV JK350
1985 CJ8 Scrambler
 
That was a good read. Back in the day when I got my ZJ regeared the shop was adamant about using regular gear oil instead of synthetic. They said it absorbed heat better. Not being a heat transfer expert I folled their advice. I think if synthetic lubricates better there is less heat to transfer. I followed their directions to make sure they would warranty their work. Any thought on this or oil preferences?

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Awesome info!! That is why I love this forum, real world experience and first hand knowledge!! Thank you fellow jeepers!:clap2:
 
I just got me 15 JK re-geared and am going through the breakin period which got me wondering. When you buy a brand new jeep no one tells you to do any kind of breakin and change your diff oil after 500 miles. So how is it new vehicles dont require you to do this? Plus how do the gears get broken in then?

Gears on the Jeep get lapped at the factory prior to you getting the car at the dealership, this does not happen on aftermarket ones so you have to do a Break in period. I still break in my new cars for the first 1K miles anyways, something my old man taught me to do.
 
Excellent info in this thread! I just got my East coast gear supply Dana 60s under my WJ , now waiting on 37s and 8 lugs wheels to show up , im going to break in the 4:88 gears with Lucas gear oil.
 
Excellent info in this thread! I just got my East coast gear supply Dana 60s under my WJ , now waiting on 37s and 8 lugs wheels to show up , im going to break in the 4:88 gears with Lucas gear oil.

Nice! That’s going to be a sweet setup


2015 JKUR AEV JK350
1985 CJ8 Scrambler
 
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