breaking in new gears
TECH Enthusiast
Joined: Apr 2002
Posts: 644
Likes: 0
From: Sugarland , TX
Re: breaking in new gears break in is relative.. i really doubt anything would happen if you abused the hell out of the gears 5 min after you were done...but breaking them in can be by heat cycling them... drive and let them get hot, stop and let them cool down. drive some more and let them cool down. i dont think 500 miles is totally accurate but it coudlnt hurt
Re: breaking in new gears You have to break them in. There is this phosphorous coating on them that needs to be worn off. 500 miles will do. Just don't go WOT on them in that time. Try to keep trips short. Gear oil gets real hot.
TECH Fanatic
Joined: Dec 2001
Posts: 1,060
Likes: 0
From: MI
Re: breaking in new gears When the gears are installed you should run the car in gear on the lift for a while and then let the rear end cool down and then take the car out for a normal run for about 15 min. then stop and let the rear cool again for about 10 min. and do the same thing again and those gears if they were setup right are ready to go.
Re: breaking in new gears just think of it as you were buying a brand new car with like 8 miles on it. for those 8 miles it probably had the **** ran out of it. i used to be a mechanic at a ford dealership and a dodge dealership and when i broke in a vehicle i ran the heck out of it. plus how much would you actually baby it if you was to buy your car brand new? just my 2 cents.
Re: breaking in new gears Heat cycling a new gear set allows the high pressure additives in the gear lube to go into the pores of the steel. Drive normal for 15 to 20 minutes then let them cool for an hour. Do this 3 times and your all set. As per DTSs install sheet, break-in procedure.
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Re: breaking in new gears My experience has been exactly as Al noted. Drive the car gently for about 30 miles - preferably under varying conditions (don't stay at any one speed too long) and NO aggressive, WOT type stuff 
Then let it cool completely. Do this 3 times. When I was breaking in the 4.10's in my C4, I found Highway 9 to work really well. You can't really go too fast and you get a good variance in speed. Just take a 30-45 minute trip, come home, and let the car sit overnight. Then do it again the next day, etc.
After this heat cycling is complete, take it easy until you've got about 500 miles total on the new gears and keep it under ~65mph. After that, change the fluid and let 'er rip
Then let it cool completely. Do this 3 times. When I was breaking in the 4.10's in my C4, I found Highway 9 to work really well. You can't really go too fast and you get a good variance in speed. Just take a 30-45 minute trip, come home, and let the car sit overnight. Then do it again the next day, etc.After this heat cycling is complete, take it easy until you've got about 500 miles total on the new gears and keep it under ~65mph. After that, change the fluid and let 'er rip
