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BlackDiamondBound
10-31-2004, 08:39 PM
i heard this guy say he blew his gears because he drove from tahoe to the bayarea (a couple hundred miles) the day after he installed his gears. is there a warming up period after you install new gears in the axles?? he said that after new gears are installed you should not go over 55 mph for 1,500 miles. is that true? anyone heard of this before?

LouisianaZJ
10-31-2004, 09:13 PM
true

OverkillZJ
10-31-2004, 10:16 PM
under 50 for first 500 miles, THEN CHANGE THE FLUID.

Only, to do it right... Drive like 2 miles, check the cover temp (it will be HOT) - let it sit and cool, then 4, then 8, then do a good 15, then just keep going for an hour and letting it cool.

Not many of us do it that way, but it's the right way to do it...

BlackDiamondBound
10-31-2004, 11:18 PM
ok thanks, so anytime it gets hot let it sit for a bit. how come new gears do that?

get so hot that is

OverkillZJ
10-31-2004, 11:35 PM
ok thanks, so anytime it gets hot let it sit for a bit. how come new gears do that?

get so hot that is

I'm not a guru on it, so if I say something dumb anyone notices, feel free to step up, whoop my ass, and correct me ;)


When you set gears, it's down to .001" - that still leaves for significant room for the metal to wear and rub against itself while it litterly "shapes" and rubs that gear pattern into the metal. If you do it too hot too long, not only can you cook the seals, but you can break down the diff oil to the poitn where it no longer lubricates. After that, you're done!


Pretty much, it's just friction. Then you change the fluid because it is, literaly, full of lil' metal chips. You'll see it has a silver tint.

gsh
11-01-2004, 07:43 AM
Another thing that goes on is work hardening. The pressure and heat on the gear mating surfaces will further spot harden the gears exactly where needed. If you allow things to cool as mentioned above and don't run too fast for too long.

I heard some say not to use synth during breakin.

Alaska ZJ
11-01-2004, 10:15 AM
Work hardening and Break in are absolutly crusial to having a long living gear set.

Drive 10 miles and park the Jeep for a couple hours. Drive the next stretch of about 50 or so. Let it sit until completly cool.

Drive 100 and let it cool.

This entire time avoid harsh acceleration and long uphill climbs (Tahoe...lol).

After that 2nd 100 drive another 3-400 and try to avoid harsh acceleration and always keep the speed under 60.

Change the Fluid.

Drive as normal.

You don't have to do it this way, but if you do you will surely get 100k out of a set of properly set up gears.

RufftyTuffty
11-01-2004, 10:51 AM
ok thanks, so anytime it gets hot let it sit for a bit. how come new gears do that?

get so hot that is

Close tolerances as stated above....and i've been told they coat the gears with a chemical that hardens them....this is why you NEED to change the oil after 500m...if you don't this chemical will burn your gears up.

I think it's Hydrogen Perocide <sp>.

JeepinHank
11-01-2004, 11:12 AM
I believe the coating is some sort of phosphorus.

Also, from reading the Yukon installation guide that was stuck in the box I got Thursday (Thanks PeakZJ) - they recommend that you shouldn't tow for the first 500 miles. Then, on your first outing with a trailer, you should drive the first 15 miles, then stop and allow the diff to completely cool. (I guess that goes back to the work hardening comment above.)

BlackDiamondBound
11-01-2004, 02:25 PM
i will defently do this. lol, its going to take me a long time to get back from the guys house that is installing them for me. he lives 1 1/2 hours away from my house, so with stopping cooling then driving and stopping ect it should only take 6 hours to get back :lol: thanks for all the info guys!