AZJeeper

Courtesy of Randy Lyman (Randy's Ring and Pinion):

Even with synthetic oils, I still recommend the following procedure for breaking in a new gear set: After driving the first 15 to 20 miles it is best to stop and let the differential cool before proceeding. Keep the vehicle at speeds below 60 mph for the first 100 miles. I also recommend putting at least 500 miles on the new gear set before heavy use or towing. During the first 45 miles of towing it helps to go about 15 miles at a time before stopping to let the differential cool for 15 minutes before continuing. This is necessary because not all of the gear tooth is making contact until it is heavily loaded. When towing, the teeth flex to contact completely, and cause the previously unloaded portion of the teeth to touch and work harden. All of this may seem like paranoia, but it is very easy to damage the ring & pinion by overloading before the teeth are broken in. If you take it easy on a new ring & pinion and keep it full of high quality oil, it should last a lot longer.

CerOf

I've always wondered when you buy a Jeep or any vehicle really, you don't have to break in the gears?

I'm not a total stranger to gear swaps having dine 4.56 on my old ZJ.

lowrpmtork

Yea.... me too. There's always a section on engine break-in, but I have never seen a vehicle with gear or tranny break-in info.

08yellowx

never a break in, never a problem

raidue

I too have wondered that. The shop I am going to have do my gear swap told me that is all paranoia to change the oil that soon and stop every 50 miles. They said no one is ever going to say its bad to be cautious but they said it is not necessary.

They also mentioned all the diesel 1tonnes and such that guys are hauling heavy loads starting day 1.

I have to agree that it does seem to defy logic. :confused:

Mad-Hatter

Wait, OP: are you just talking about when you take off from a stop it goes through the rpms a lot faster and shifts really quickly until you get to speed? That is the whole point of the gears

f3arn0FJ

After 500 miles a lot of small chunks and shavings came out of my diff from the break in. I wouldn't want that stuff in there for 20k miles

raidue

Agreed. That's all they recommended was just monitor for shavings and change when the need arises. Course that will be harder to monitor with my new riddler covers.

AZJeeper

Check your owner's manual. There's an engine break-in procedure. If you follow that, you are pretty much aligned with breaking in your gears as well.

True, but the RAM 3500 has an engine break-in procedure too. In fact, it is identical to the JK's.

There's nothing wrong with hitting it hard from mile 1. It's just the gears will temper better and MAYBE last a little longer if you break them in.

mpkelley20

Yeah, I was suprised how much I cleaned off the magnets after my break in period. I had changed my original diff oil (pre-gear install) after maybe 5000 miles (deep water stuff) and I had nothing like what i had when I broke in my new gears.

I asked the question a while ago about why new gears don't need to be broken in and someone did respond with a logical answer. I don't remember the exact answer but I know it had something to do with the gears already being broken in at factore or something like that. Wish I could find that post......