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My car is in the shop getting 3.90 gears putt in as we speak. I was wondering is there a special way to break them in??:headscratch: and how many miles should i run it before i really put them to the test? Thanks
 

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some people say heat up and cool down a few times

( drive for 20 minutes let cool and repeat )


i took the safe route.

500 miles of easy driveing.


and some say you dont need to at all, even though it clearly says it on the box....
 

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i would def drive 500 easy miles. Like mentioned, some say that you can beat on it when you leave the shop. I've had gear swaps done probably around 10 times and always broke them in easy.
 

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ok thanks i will do that. and yea ill probably give it 500 miles too.
 

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a couple of heat and cool down cycles is all you need. gears are made to put in and go. put mine in on friday at the track on sat no issues at all.
 

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I had mine installed and took a ride with my mechanic and got up to 5800 rpm the very 1st time I drove it. He said get after it, just don't be drag racing for the 1st 500 miles. It did not take long to get the RPM's up. it was a nice dif.:bigthumbsup
 

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i went in thinking i should break them in but the guy that did them for me insisted (on him) that they would be fine right off the bat. tested em out right after i left :gringreen.
 

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Drive for 500 miles or so, without pounding the throttle and no gear assisted stops....after that get ur differential oil changed cuz there will be alot of metal shards that shave off from the wear pattern breaking in that you wanna get out of there...i reccomend full synthetic after the 500....be sure to put in conventional oil during the break in period to allow proper heat cycles, its not a good idea to jump on the gas right out of the shop because the metal isnt heat treated and it can warp under high heat and pressure before break in is done. full synthetic oil will keep it to cool during break in which is bad so remember conventional oil first 500 miles then ur free to ride...
 

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Drive for 500 miles or so, without pounding the throttle and no gear assisted stops....after that get ur differential oil changed cuz there will be alot of metal shards that shave off from the wear pattern breaking in that you wanna get out of there...i reccomend full synthetic after the 500....be sure to put in conventional oil during the break in period to allow proper heat cycles, its not a good idea to jump on the gas right out of the shop because the metal isnt heat treated and it can warp under high heat and pressure before break in is done. full synthetic oil will keep it to cool during break in which is bad so remember conventional oil first 500 miles then ur free to ride...
there is no need at all to change the fluid after 500 miles thats total BS. When you buy a new car with 0 miles do you change the gear oil after 500 miles no. dont put out incorrect info if your not sure.

drive 20 miles park and let cool repeat that a couple times and your good to go. its never failed me. like I said before gears are made to put in and go.

In my 25 years of turning wrenches I never heard such nonsense.

gears warping:headscratch:
 

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The most important part is the heat cycles of heating them up and cooling them down completely by driving it like a little old lady. 500 miles is a good rule, but its more important to drive them for say 20-30min very easy, let the cool down completely, and do this a bunch of times. The easier you break them in, the less chance you'll have of developing problems later like whining or failures.
 

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there is no need at all to change the fluid after 500 miles thats total BS. When you buy a new car with 0 miles do you change the gear oil after 500 miles no. dont put out incorrect info if your not sure.

drive 20 miles park and let cool repeat that a couple times and your good to go. its never failed me. like I said before gears are made to put in and go.

In my 25 years of turning wrenches I never heard such nonsense.

gears warping:headscratch:

yes change oil....


after 500 miles change it.

it will get gear shards, dust deposits, gear covering, ect ect off.


stock gears are cleaned at the factory.


i also use full synthetic, personally i used RP. its quite easy to do


put car up on jack stands.

unbolt rear cover

crack it open with a screw driver and let drain

add new RTV
then refill.


in the v6 tech in my DIY garage theres a list on how to do it on a V6, if you decide to do this let me know if the measurements are the same?


but def change oil!

and id wait 500 :) to be safe


like i said everyone will say somethign different do what you feel is right :)
 

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yes change oil....


after 500 miles change it.

it will get gear shards, dust deposits, gear covering, ect ect off.


stock gears are cleaned at the factory.


i also use full synthetic, personally i used RP. its quite easy to do


put car up on jack stands.

unbolt rear cover

crack it open with a screw driver and let drain

add new RTV
then refill.


in the v6 tech in my DIY garage theres a list on how to do it on a V6, if you decide to do this let me know if the measurements are the same?


but def change oil!

and id wait 500 :) to be safe


like i said everyone will say somethign different do what you feel is right :)
stock gears cleaned at factory what are you smoking? so they spin them for 500 miles before installing the rear then clean them?:headscratch:


I changed mine after 3000 miles and it was still clean as it was when I put it in. I run amsoil I think its about the best.

If you want to throw money away hey then change it.

gears are very very hard and when installed correctly you should have no issues with any metal shavings etc. I have never seen dust deposits in a rear?

to each there own like I said I have been turning wrenches for 25 years and never changed any oil after 500 miles and never had any rears fail.
 

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Yea im going to have to agree with johnr2001. I worked at the ford dealership for 4 years and ive never herd of changing rearend fluid after 500 miles of installing a set of gears. You do want to do the drive and cool down cycles a few times but after that run the crap out of it :bigthumbsup
Jimmy B..
 

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I also agree with john and jimmy, the factory doesn't break in anything and change the oil, and as far as needing to change after 500, its pretty much a waste, it can't hurt at all, but its money better off spent elsewhere. And as far as I've seen for lubes, Amsoil and royal purple are pretty much the best around, with the edge going to amsoil.
 
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