The only break-in will be for your ring and pinion if they are new.  If they are a used set and you have the pattern and backlash properly set you are good to go.  I've installed three truetracs and never had a problem.  Make sure that you read the instructions carefully on the fluid - they don't need friction modifiers.
If you installed a new ring and pinion, use the break-in recommendations from the manufacturer.

So with a Eaton Truetrac new pinion gears is it differnt than traditional  set up as far as breaking in....I keep googling Breaking in Eaton Truetrak and it says no break in and no friction additives just GL5 rated 80w-90 gear oil should be used. 

GPatrick wrote:

Not sure why you don't believe them.  No break-in is required for the carrier.  You do need to break in the ring and pinion.  Focus on that and don't worry about the carrier - there's no clutches and the internal gearing is made of precision components that don't need break-in.  

Here is one of many links that can be found on-line regarding ring and pinion gear break-in.  https://revolutiongear.com/blog/ring-and-pinion-break-in-procedure/#:~:text=The%20suggested%20break%2Din%20procedure,this%20process%202%2D3%20times

The primary purposes of the break-in procedure for the ring and pinion are noise and longevity.  A drag racer isn't going to put 500 miles on a race car to break in the gears - but the car will never probably see 500 miles in its lifetime.  For a ring and pinion in a car where you're going to put several hundred thousand miles on it and where you want it to be quiet, the break-in procedure is important.  

https://revolutiongear.com/blog/ring-and-pinion-break-in-procedure/#:~:text=The%20suggested%20break%2Din%20procedure,this%20process%202%2D3%20times

I believe them was just making sure on the procedure on the ring and pinion or if it meant all of it I bought it as a unit at Quick Performance all new they even threw in a new 8-inch nodular case that I did not even ask for I said I just wanted the reconditioned 8 inch.....probaly easier for the guy to grab the nice new clean 8 inch nodulr off the shelf. I would have just gone with a 9 inch but I had just put rear disc on this rear.
 

Last edited by BILLY WALTON from GEORGIA (3/30/2024 11:29 AM)

Texas! wrote:

If a new ring & pinion need a break-in period why is there nothing in the Owner's Manual of a new car/truck about it?

Probably because the manufacturer doesn't care so long as its not necessary to get the rear past the warranty period.  Or, because the gears may already be lapped in or something at the factory making it unnecessary. 

Every set of gears I've ever bough that came with instructions stated you should change or oil after driving a shot distance or time.  I live by the maxim that oil is cheap, but the stuff it lubricates is expensive.  The minor inconvenience of changing the oil after running the gears in is small compared to peace of mind, AND the manufacturer having to honor the warranty in the even of an issue.  BTW, its not a break in period.  My understanding is that you are simply removing any metal or gear coating that is shed due to everything being new.  I've rebuild a bunch of rears and there's always some trash in that initial oil change.   

As far as the Truetrac, no, nothing special required.  I run one in the rear of my F250, and installed it after a full rebuild with new Yukon gears.  I changed the oil after 50 miles and all seems well. 
 

MS wrote:

BILLY WALTON from GEORGIA wrote:

So with a Eaton Truetrac new pinion gears is it differnt than traditional  set up as far as breaking in....I keep googling Breaking in Eaton Truetrak and it says no break in and no friction additives just GL5 rated 80w-90 gear oil should be used. 

You want to break in your new GEARS, not the atri-Trac

I been driving it a little each day up the road about 15 miles and and back home.