fly boy_1

iTrader: (4)

I searched a bit but couldn't find anything o the topic, I'm having some 3.90 rear gears installed in my Z28 this week and I was wondering if there is a specific gear break in procedure I should follow? At the shop they said just give it 300-500 miles before beating on it, however from all my research with aftermarket rear ends they have very specific break in procedures.

So my question to you all is if there is no specific routine, is there anything to avoid? I'm assuming you'd want to vary speed on the car vs traveling at a constant speed (driving it home on the freeway the whole time a bad idea?). I've also seen some things with aftermarket rears saying to keep speed low initially while the gears are new and to heat cycle them to help surface harden the gear material?

Thanks for any help you can provide,

Eric

skopers3

iTrader: (3)

The box of my Motives said 500 miles. Yes, you should avoid long highway trips.

02ws.sik

I always heard 500 then change fluid.

bestlude

iTrader: (4)

I broke mine after 400-500 miles.. and within that time period i drove for 30 min and let it cool for about an hour or so (for the 1st 100 miles). Then the rest i drove 30-45 min and let it cool for 15-30 min.
Not that you have to do it my way religiously. But thats kind of the way i did it

fly boy_1

iTrader: (4)

Ok, just wanted to make sure. Much appreciated everyone.

02ws.sik

The reason for the new fluid after break in is less chance of whine and gets all of the shavings off from the break in.

fly boy_1

iTrader: (4)

On that note, what kind of fluid/additives would I want to use?

02ws.sik

If its the stock rear or a 9 inch posi use conventional 80w90

Franchi

I beat on mine day after I installed it and never had any issues. But I suspect it was mostly because my friend who helped/did majority of it did it just right, shimmed in. And I used Royal Purple if I recall....All I remember it was some expensive *** gear oil. lol

02ws.sik

Yes royal is very expensive but some of the best stuff.