DaytonaBlues

hello all, i just got a 99 Z28 M6 for not a lot of money and while doing a fuel filter i wanted to check the rear end, so.. with both rear tires in the air in neutral i spun the left rear tire, the other tire spun the opposite way. that being said, i put the car IN GEAR while still in the air i spun the left rear tire and the other side tire did not spin. HMMMM. the RPO code on the door says it has the g80 and gu6 option. which is limited slip and 3.42 gear. i know that if you spin one tire by hand, and the other spins the opposite direction, you dont have posi...someone PLEASE help me out....

thanks guys..
-matt

LS1TA_956

iTrader: (1)

try doing a stand still burnout and check if both tires spin

ULTIMATEORANGESS

iTrader: (4)

thats all.



but them spinning in opposite directions is normal.

DaytonaBlues

Well ic the.wheels.spin opposite directions is normal, i guess what u guys say is just lay a patch and see If both spin? I'm going to change the gear oil in the rear end FIRST. JUST I'M NOT SURE what weight oil to use. I know I need the GM posi additive and Im gonna use 75w90 synthetic Mobil 1 gear oil. Before I go and try my first burnout and pray the posi is in good shape. Any other suggestions or things to look for when I pop open the diff cover? Car has g80 and gu6 rpo code on the for sticker
Thanks for any and all help guys

ULTIMATEORANGESS

iTrader: (4)

check your pinion seal for leaks and replace while youre there if needed.

redbird555

iTrader: (14)

yup go do a burnout to confirm everything is fine. but the torsen works by using worm gears, when you spin the tires on the road the load on the tire from the pavement makes the worm gears climb on top of eachother and lock the tires together. with the car in the air there is no load on the tires so the worm gears dont work and the tires dont lock

therabidweasel

iTrader: (5)

Your gear oil combo is wrong. If you have an auburn you want dino oil add friction modifier. If you have a torsen you can go synthetic and do not need friction modifier. I don't know the codes off hand, just verify which diff you have.

DaytonaBlues

What!! So if i got a Auburn In there I gave to use petroleum based gear oil? And friction modifier you mean the posi additive you get at the dealer right? I decoded all my rpo codes on the door sticker and I got no code.that told me what diff.I have. idea how to tell what diff.is.in there? U sure I cant use synthetic? I was gonna put synthet Royal Purple in everything ??????????