Diff gear break-in?

RatLabGuy

RatLabGuy

You look like a monkey and smell like one too
Joined
May 18, 2005
Location
Churchville, MD
Well hopefully by this evening I'll have my new 3rds in place and ready to go.
Rear is new gears, just setup with a hardly-used TruTrac. Front is stock from another vehicle but been sitting quite awhile. Since it's open manual hubs anyhway that one is only turning off-road anyway.

Anyhow - is there any kind of specific "break-in" procedure?
I figured I'd fill 'em w/ generic/cheapie 80w90 now, then drain/replace in about 100-200 miles to get out what little metal shavings there may be, marking paint etc, then put in better stuff. Anything else?
 
general rules...

- don't hold a steady speed (like getting out on the interstate)

- don't run for long periods of time without letting them cool off (like getting on the interstate)

- usually the first drain is 500 miles, then use good stuff...but doing it at 200 or so, and then again between 500-1000 wouldn't hurt

really just crank it up and run errands, or back-and-forth to work, etc for a couple hundred miles...

Greg
 
you need to drive short distances, (like around town) no more than 30-45 min each, and letting it cool down between drives. This tempers the gears, and hardens them into the wear pattern together. This should be done at least for 300 mi, i did mine for 500 mi... if you just take off on a long trip, or pull a heavy load before you do this, they are more than likley going to start roaring, and ruin your gears., after break in time (300-500mi) change gear oil and you're good to go :beer:
 
Ok, thanks.
Sounds alot like break-in for an engine rebuild....

unf I have a 12 mile highway commute to work. Luckily, ths isn't my dd... which also means it will take a good month to hit 300 miles...
 
I've been told you don't have to put a couple hundred miles on them. Just give them a few good drives around town, with 30-45 mins to cool down like the others have said.

I will be doing this in a number of days, and I'm not going to have the time to ride around town for 300 miles before I have to be back at school. Might be able to stop and eat for 30 minutes in between but I cant really avoid th constant speed part. I'm not worried.

Plus, if this was the case, it'd take you forever to break in your front gears. Just a thought.
 
You do need to heat treat the gears properly. Josh quoted our recommendations that we use based on every major gear manuf. recommendations.

Andy
 
I jack mine up and let them run ( if a manal tranny) in 4th gear idling for about 20 minutes and let them cool. Then I make 4 or 5 20 to 30 minute drives around town and let them cool. Each cooling period is about 4 hours. After that I drain the fluid and replace. When I geared my tacoma I did the initial run and later that night I got frisky and was running the hell out of the gears down the interstate w/ less than 20 miles on the setup. Chance luck or not but I never had any problems with those gears in the 4 years I ran them. All my other axle builds i went through the break in period w/ no problems.
 
Wow yea, I def did none of this when i got my Z71 regeared a long time ago. That was before I knew what the heck I was doin and let 4WP do it cause they were havin one of there 1/2 off labor sales. They told me to just come back in 500 miles so they could change the fliud and to not tow anything until then. Never mentioned anything about heating/cooling periods or not doin interstate driving, as a matter of fact the first bit of driving I did was interstate on the way home. I mean the Z71 has been my DD from then since now (almost 3 years since the regear) and I havn't had any issues other than blowin out my pinion seals not too long ago which was still covered by the warranty. maybe thats why my diffs make so much frikin noise. Especially when they first did it and I'd be the interstate and let off the gas it sounds like I have a turbo winding down, nowadays its more of just a grindingish/whinningish noise :confused:

fawkin 4WP
 
Someone else mentioned this, but I have always put the rear on jack stands and ran it 10-20 minutes first.

Of course youu need to follow some standard safety precautions and make damn sure it aint coming off the jack stands.

But I like ZERO load for 10-20 then a short trip with no jerks (ok the one behind the wheel but no hard starts or such)then drain and refill.
Then 500 then drain and refill with synthetic.

I am a huge fan of synthetic diff grease. And the cost is only 1 time unlike oil changes...
 
jrraw23 said:
Wow yea, I def did none of this when i got my Z71 regeared a long time ago. That was before I knew what the heck I was doin and let 4WP do it cause they were havin one of there 1/2 off labor sales. They told me to just come back in 500 miles so they could change the fliud and to not tow anything until then. Never mentioned anything about heating/cooling periods or not doin interstate driving, as a matter of fact the first bit of driving I did was interstate on the way home. I mean the Z71 has been my DD from then since now (almost 3 years since the regear) and I havn't had any issues other than blowin out my pinion seals not too long ago which was still covered by the warranty. maybe thats why my diffs make so much frikin noise. Especially when they first did it and I'd be the interstate and let off the gas it sounds like I have a turbo winding down, nowadays its more of just a grindingish/whinningish noise :confused:
fawkin 4WP
Click to expand...

Or it could be those crappy brand of genuine gear they use. I've known several people to run them. One guy went through 5 sets. They kept giving him new new sets and it didn't matter where you set the backlash at they still roared. There's a reason they have that no questions asked money back guarantee.
 
Josh C said:
Or it could be those crappy brand of genuine gear they use. I've known several people to run them. One guy went through 5 sets. They kept giving him new new sets and it didn't matter where you set the backlash at they still roared. There's a reason they have that no questions asked money back guarantee.
Click to expand...


Figures, yea I mean the roar doenst really bother me, I just keep my fingers crossed that they'll keep on holdin together.
 
used oil after break-in

I drain the break in oil into a clear quart jar (like used for canning vegetables). Sit the jar or jars on a magnet. After it sits for a week it can be used as spare oil on trail days. Absolutley nothing wrong with it except fine metals shavings that go to the bottom. One thing I learnt about break-in, its not as important when you change ratios every year!
 
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