Thread: 4.10 break in
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      06-18-2009, 07:55 AM   #14
J08M3
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Drives: 2011 M3 COUPE
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Quote:
Originally Posted by CanM3 View Post
of course there is a break in with a new gear set......the ring and pinion have to establish a wear pattern on each other and they have to go thru a few heat cycles during this time period before they can be heavily loaded.
the oil change is designed to rid the oil of any metal contaminants that WILL be there after the break in cycle.
the engine rpm's really dont come into play as much as speed and acceleration. Whenever we installed new ring and pinions, the manufacturer would advise no hard acceleration for the first 500km's, no towing for the first 1000 km's, and no going over 120km/hr for the first 500 kms.
After picking up from the shop, try not to drive more than 100 kms and then let the vehicle sit for around 6 hrs.....to allow the diff to cool (a heat cycle).
The contact surfaces on a ring and pinion are surface hardened, if this hardening is damaged during breakin, when tolerances are tighter, the problems wont show up for some time.

You can get in a vehicle and romp on it right away, but the chances are higher of wiping the tooth contact areas on the gearset..

Also, the pinion bearings and diff case bearings need time to seat. They are installed with a pretty good preload on the bearings, so there will be alot of heat generated for the first little while. I'm sure the Dinan diffs have new bearings as well as a new gear set...they would probably go thru the diff case and inspect the posi internals as well as the spider/side gears..

good point. thanks for sharing
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