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Break in period?

4K views 7 replies 7 participants last post by  okstatejk 
#1 ·
Picking up my Jeep this afternoon after the dealer replaced the transfer case and rebuilt the rear differential. Mechanic acted like he wasn't aware of any break in period, my question is...isn't there? What exact driving instructions must I follow to properly break in both the new TC and diff? Do I need to change the fluids after a certain amount of miles?

Thanks!
 
#2 ·
Can't speak to our Jeeps but have had similar situations with racing and Camaro's I assume the theory is the same.
Common sense prevails, Go easy.
- multiple heating/cooling duty cycles
- Use the operating aspects of the parts (shifting etc.)
- Go easy for 200-300 miles and/or half a dozen duty cycles
- If it were me, I would change the fluids after 500-600 miles assuming (again) you have cycled several times and "exercised" the moving parts.

IMO, break-in is as much about what you do as well as what you don't do.
DO use it - DON'T Abuse it.
and you'll be fine.
 
#3 ·
I just had my rear diff rebuilt and right rear axle replaced after a warranty issue and asked the rep from the service department if there was a break in period I need to follow he said he wasn't sure but he thought no. I asked him to check with the service manager and the manager came out and told me that there is no break in period......still think that's kinda weird tho
 
#4 ·
A new JK recommended break in period is for the entire drivetrain. It doesn't hurt treating it the same at this point. Some drive it hard out of the box with no noticeable problems down the road. Being conservative for a few hundred miles can't hurt. I can only tell you that if that was done to my JK, I would change the transfer case and dif. fluid after approx. 3,000 miles; pull the dif. cover and inspect the gears, and then re-fill with synthetic. It's easy and inexpensive to service both. Servicing it early like RubiconSS said can't hurt either. Your call.
 
#6 ·
Key aspect that needs to be mentioned.... It ALL depends on who is doing it.
Reason I mentioned the interval I did was, I'd be doing it myself ($20-30 bucks, why not)
IF they are doing it..... No way. Get them to put in writing on the work order
"No special break-in required" then IF something breaks or wears out prematurely you have something to fall back on.
They are going to charge you like $160-200 dollars to drain and refill.

As kik correctly points out, standard break-in takes into consideration the entire drive line.
Only difference here IS, it's not a robot in a squeaky clean factory that just climbed inside your drive line.....
 
#8 ·
When I re-geared, I followed this:
Short, low speed 25 minute initial heat cycle.
First 500 miles: Keep speed below 60 MPH, keep driving distances limited to 30 minutes or less. If driving more, stop every 30 minutes for 15 minutes or so.
No hard starts, towing, or quick acceleration for first 500 miles.
After the 500 mark, drain fluid, check magnetic drain plug for large metal chips. Small metallic flakes are expected. Fill with fluid of your choice. Enjoy.
 
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