alek72us

I have a 72 olds 442 with a 10 bolt 8.5

if i have the the car jacked up and turn one tire the other tire will stay at still tell about a 1/4 of a turn then start rotating the same direction. then i can turn the tire the oppisite way and the other tire will do the same thing stay at still tell tell about 1/4 then it will start spinning.

Is something broken?

i have yet to take the cover off and look in there. and i bought it with the engine not running so i have never put and power to it.

thanks
alek

svnt442

It sounds like the brakes are dragging.

halfmoontrail

Sounds like a posi rear end, probably fine.

alek72us

i know its not the brakes.


so some posi's are like that then?

svnt442

They shouldn't be, but if it is then it may need a rebuild.

At any rate I would pull the cover to inspect what is going on in there.

alek72us

I will rip into it within the next two weeks. i just was wondering if it was like a true posi or a limited slip. or where one would go then the other would catch on.

thanks i will let u know what i find.

svnt442

Oh jees. A "posi-trac" is GM's name for a limited slip differential.
Other names are:
Alfa Romeo: Q2
American Motors: Twin-Grip
Buick: Positive Traction
Chevrolet/GMC trucks (after 1973): Gov-Lock
Chrysler: Sure Grip
Dana Corporation:Trak-Lok or Powr-Lok
Ferrari: E-Diff
Fiat: Viscodrive
Ford: Equa-Lock and Traction-Lok
International: Trak-Lok or Powr-Lok
Jeep: Trac-Lok (clutch-type mechanical), Tru-Lok (gear-type mechanical), and Vari-Lok (gerotor pump)
Oldsmobile: Anti-Spin
Pontiac: Safe-T-Track
Porsche: PSD (electro-hydraulic mechanical)
Saab: Saab XWD eLSD
Studebaker-Packard Corporation: Twin Traction
TVR: Hydratrak

Other than that you have either an open diff (full differential action with no torque transfer), a locker (mechanical, pneumatic or electric) or a spool which locks boths axles together without any differential action.

alek72us

Lol ok. thanks.

507OLDS

Do you have the transmission in park,when you are spinning the wheels,or do you have it in neutral? You should have it in neutral.Then have someone hold one of the wheels while you spin the other.If you can spin one wheel,while the other is being held,then it is an open rear.If you can't spin the wheel because the other one is being held,then you have a posi.

alek72us

The transmission isn't in it. if i have someone hold one side. i can move the other about a 1/4 of a turn then it will catch with the other and not move. then i can move it the oppisite way and same thing it will move a 1/4 of a turn the stop.

Its like there is a 1/4 turn of play before the oppisite tires catches on then it will spin the same way as it. and i can turn it and turn it and they will stay in the same spot. until i go to turn it the oppisite way a 1/4 with just one wheel then the other will catch on.

thanks
alek

507OLDS

Sounds almost like a Detroit Locker,which is a coupler style unit,but I have seen some worn posi rear do the same thing.Best thing is to pull the cover,and see what you have.