just got the package today!! i was reading the box and in kinda small print it said "break-in period required". they are motive 3.73's for a 7.5" rear. so what's the break in period for'em? i read the instructions and it didn't mention anything. also when i ordered them i got 2qt's of royal purple gear lube, the only selection AM had was the 75w-90. the instructions call for EP85w-90. do different gears use different lube's? or is the 75w-90 for the 8.8 rear end? also, are motive gears a good gear to be using for street and some strip use? great time for me to ask that Q eh? lol anywho, thx in advance for ya'lls help!

oh yea, 2qt's for the sixxer rear end? or 3?

 

When I got my 4.10s they said to take it easy on the gears for the first 500 miles. They said it was best to drive the car long enough for them to get to normal operating temp (about 30 minutes) and then let them cool for several hours during the break in period.

Every installer is going to tell you a different method though.

 

do you remember what weight oil/lube they used?

 

They used the stuff in AM's gear "kit" (royal purple) and also added some friction modifier. I recommend having the bearing replaced while they're in there too otherwise it will start to whine just like mine.

 

yea i planned ahead and got the motive bearing/install kit on this one. so ya think just go ahead and put the 75w-90 in there? i just scanned thru a jeg's mag i had layin' around and i didn't even see any 85w90, does it exist? lol and would typical auto parts stores have the friction modifier?

 

You should be fine with the oil they gave you and I'm pretty sure it actually has some friction modifier in it already.

 

Just run what Ford recommends and add some extra friction modifer in if you also rebuilt the posi-unit as well. Otherwise, take it easy for 500 miles in which you flush the diff at 500, and then you're good to go.

 

take the car for a test spin with the windows up and radio off. basically you are listening for any grinding or whining. If all is good, let 'er rip. I had mine sideways leaving the dealership.

 

yea i'm going to order a brand new one...so basically, drive like a g'ma for 500 miles (which sucks because i really only drive it on the weekends, and that's maybe 100-200 tops!), flush the diff, put all lube in and i'm good to go? schweeet!

 

as long as you don't hear any grinding metal etc after the first 50 ft, rip it loose

 

lol, yea the grinding metal sound is never a good sound.

 

Wait, After 500 Miles You Need To Flush Old Lube ???

 

that's what i've heard quite a few ppl on here say/post. i'm not sure i fully understand the purpose of that tho...unless it's to remove little shavings of metal that may come off during break-in...hmm..anyone?

 

Mine wasnt flushed. youll be fine...

 

awesome. on the royal purple bottle it says sumthin' about it being used for limited slip differentials...so it has a friction modifier in it? i noticed CCM said to run extra in it, i happend to pick up a tube of it and it says to not over treat the gear lube. opinions anyone? seems like it's 50/50, doesn't matter either way...

 

royal purple has friction modifier in it. most of the better lubricants do. i run a little extra in mine, and I use amsoil.

 

hmm, nvr heard of amsoil...but yeaa i think they effed up the instructions for the install of the gears, they're calling for EP85-90 gear lube. i've looked EVERYWHERE, i'm just going to assume they MEANT 75w-90 and call it a day. and of course there's no type of contact info on the box. only thing i found was the "made in Italy" sticker, lol. how are ya suppose to get them to warranty a product if there's no way to contact them? i haven't googled'em quite yet tho, that'll prolly get it. but still, put a damn web address or mailing addy on it or sumthin'!

 

I run 75-140 in mine, simply because it may see harsh times at the track or strip.

 

hmm, think it'd make that much of a difference for occasional track use, and some foolin' around? i've got 2 qts of royal purple 75-90 already, pointless to return to AM...think it's worth goin' to local autoparts store and gettin' some 75 or 80-140?

 

use what you have.

 

The purpose of flushing after the first 500 miles is that during that time period, the gears are creating a wear pattern on the teeth which results in extra metal being worn off. After breakin (500 miles), flushing gets rid of that crap so that you don't have all that crap in your diff. As for friction modifier, you only add extra for break in when you put new discs in for the posi unit.