[fast79malibu]

i have a 1979 malibu with a 7.5 rear end ... i have strange axles c clip eliminators and 373 richmond gears... my question is this a full posi unit or limited slip? when i jack i the car and put in neutral and spin the tires one tire goes one way and the other tire goes the other way. so exactly what is this?

 

[Mike in Michigan]

Posi-test

If the opposite tire spins the other way, you have a conventional diff, not a posi.

 

[Bob C]

If the opposite tire spins the other way, you have a conventional diff, not a posi.

If the clutches are worn out it will do the same thing.
Bob

 

[johnsongrass1]

"Posi" and "limited slip" are the same thing.

Take the cover off and look. Change the gear oil and count the teeth while your at it.

 

[fast79malibu]

posi or not

41 on the ring gear and 11 on the pinion = 3.73 thats what i got when i counted the gears last night. when my cousin owned this car a couple of years ago he did all the rear end work to it. and every time he would smoke the heck out of the tires and it always left 2 tire marks. so as 5 or 6 years have went by i now own the 79 malibu and just wanted to be sure on what i have. thanks.

 

[Henry Highrise]

Yep...Its a posi....when you fill it back up with 80W90 gear oil....add a bottle of friction modifier to it....If you don't the clutches in it will stick and chatter when you turn corners .

 

[fast79malibu]

posi or not

my question is this ? what makes it posi to begin with ? i didnt see any clutch springs or plates or whatever they are when i had the cover off last night. i called jegs last night and talked to their tech line and they said i most likely have a open differential .... what is that ? all i seen were spider gears turing as i counted the teeth on the gears. and jegs tells me that they sell 3.73 gears for this possible type of rear end thats in my malibu

 

[fast79malibu]

posi or not

another q? is what do these clutch packs look like?

 

[jimfulco]

Two stripes do not necessarily mean it's posi. If both back tires are equally loaded, an open rear end will spin both tires at the same time.

The center portion of the posi carrier should have 4 or 5 horizontal coil springs, about as big around as a finger, or a single flat, S-shaped spring. I say "should have" because some people remove the preload springs, thinking it will make it work better. With the preload springs removed, one tire could possibly turn backwards when you turn the other one by hand.

 

[66GMC]

another q? is what do these clutch packs look like?

This is exploded view of an (Eaton) Limited Slip Differential that uses clutches:

This is the legendary "Detroit Locker" LOCKING differential (not recommended for street applications ... clicks when turning on dry pavement):

There are several other types of limited slip or locking differentials. This Auburn unit, for example ... that uses a conical frition material: