I have an 86 T/A, L69, TH700 an 10 bolt.

When I jack the car up and turn one wheel the other goes in different direction, so I figured I did not have a posi.

When I put the pedal to the medal, on even ground or when I am making turns it spins both tires.

I think my T/A´s rear does NOT have a posi but my 10 bolt thinks it has

Am I right or the 10 bolt?

Thanks in advange,

Nonni

 

if you can do a burn out and spin both tires it sounds like you have posi. the only 100% sure way to know is to pull the rear cover and take a look. most likely it wouldn't hurt to change the lube and posi additive.

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ICON Motorsports
1st & 3rd
MM Black Diamond 538 F&AM

 

This question gets asked a zillion times. It ought to be in a FAQ. You probably have an Eaton locker limited slip. The wheels will turn in opposite directions on jack stands, but if you spin one fast enough by hand the diff *will* lock up. It has a centrifugal governor to engage the clutches when the rpm difference between wheels is >100 rpm or something. Either that, or someone has put a Torsen in there.

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1985 Yellow IROC-Z 5.0 HO, T-5 3.73 Torsen, 4 wheel disks
PFCM pads, GTA wheels, Koni yellows, B&M Ripper, Dynomax

 

I'd go with the Eaton locker.

It's not a true posi and it's not as strong but it does allow both wheels to lock up. There are more of those in cars than real posi's. The only way to really tell is to pull the diff cover off and have a look.

Considering the diff oil should be changed every few years anyway, it's probably a good time to do it.

 

Ahem... Sure it's not a "real posi" because "Positraction" is GM's trademark name for the GM version of a limited slip differential. The Eaton Guv-lock is a true limited slip diff, except the clutches don't slip all the time during gentle turns like a Positraction does. They are not even engaged until they're needed, as determined by one wheel losing traction. Although not used on the F-Body for very long, the Eaton has been used by GM on a lot of trucks. The only flaw it has is when the clutches get worn they take longer to engage and come in with a bang. This can cause the rear end to step out abruptly when applying power in a turn, or put excessive stress on the unit. I think that's how I broke mine, along with the spider gears, at the drags.

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1985 Yellow IROC-Z 5.0 HO, T-5 3.73 Torsen, 4 wheel disks
PFCM pads, GTA wheels, Koni yellows, B&M Ripper, Dynomax