hello all, new guy here, just bought a hard used Z-28 the other day. today I did a small burn out and noticed that I only spun 1 wheel, is this normal? it looks to be a disc brake 10 bolt. I thought they were all posi's? some one educate me please. thanks

 

You need to have the RPO G80 to have a factory posi. Just because it has disk brakes doesn't mean it will have a posi.

 

No, definitely not all had posi.

Additonally, even if the car came with RPO G80, it might be completely worn out, as they often are; or somebody might have swapped something at some time in the car's life. So even looking up the "codes" is not a way of determining for sure what's in your rear.

As we all know, the best thing to do, since you just bought the car, is to change all the fluids. While you're changing the rear end fluid, make a point of looking inside there, and identifying what you have; both what kind of carrier, and also what gear ratio it has. Whatever parts you find in it, that's what's there; no matter what the "codes" say that the car or the rear had when new.

 

Thanks for the replies guy's, the more I ask..the more I learn. I've been doing search's on the 10 bolt and about all say the Auburn 7.5 10 bolt is not rebuildable or can't find parts for anyway. So what are my options if it's worn out? I've looked at lockers big $$bucks$$ or spool's. Of course replacement is an option too. what are your thoughts?

 

Easiest/best/cheapest/lowest-risk for most people, is to just get a 98-up rear out of a V8 car. Preferably a SS, and preferably a T-56 one. That will have the excellent rear disc brakes (FAR superior to the 82-89 ones), bigger axles than your 86, a Zexel Torsen worm-gear type "posi", and 3.42 gears, in an almost direct bolt-in package. The only problems are that it's longer, so you'll need wheels with the 4th gen backspacing; and the parking brake cables are different; and the hydraulic part of the brakes may need to be re-plumbed if the rear has the 4-channel ABS/traction control, because that setup uses 2 hyd lines to the brakes (one per wheel) instead of just one that feeds both wheels.

I think you'll find that you can buy one of those for a little more than half of what it would take to buy a posi, a set of decent gears, bigger axles, and all the parts required to assemble all that; and you'll get the nice brakes for free.