bobcatnn

Just bought an 86 Iroc and was told it was open. Now curiosity got me thinking it could be posi but it has worn. I've heard of someone selling shims to correct the wear. I have no idea though if it's that or not. Is there any good way off telling if it's an open or posi from the outside? Are there any other good ways of finding out?

SSC

Yea, it's 10 or 9 bolts. 10 bolt is 90% open and 9 is 100% posi. Also 9 or 10 bolts and 2 quarts of fluid to check My Z28 was a 10 bolt posi gov lock, had to pull the cover to find out what was.

RB83L69

Yes, it's very easy to tell from the outside. Just take the cover off and look inside.

If it's a 9-bolt, then it is a posi, and is the type that can be shimmed. If it's a 10-bolt, it might or might not be; if it isn't you can buy a posi carrier for it, and if it is, you can get the parts to rebuild it or trade it in for a rebuilt one.

You just bought the car. The very first thing you should be doing is replacing the fluids, even before you wax it. While you're replacing the rear end lube, make a point of looking at the carrier, and identifying it; and determining what gear is in it. That will save you countless frustration of posting all sorts of stupid stuff trying to get people who also can't see through your cover to tell you what's inside there.

bobcatnn

I figured I was going to have to get inside, which isn't so bad. I was just hoping there was a tag or id code on the outside. Thanks for the quick response guys.

LedZep

iTrader: (22)

Easier way to tell, jack you rear tires off the ground. Then try to turn them, if they turn its an open rear if not its a posi.

bobcatnn

well i know it acts like an open right now, only spins one tire under heavy accel. plus, just spinning won't tell you if it's for sure one or not--could be worn. Just looked it's a 10 bolt, but it has a tag on one side, not sure what it says though.

LedZep

iTrader: (22)

No if you do my method it will tell you for sure. A posi will not ever spin both wheels when jacked up no matter how worn.

RB83L69

Screw a bunch turning stuff. Take the cover and look. It's the only sure way. You have to do it anyway, since you're going to be changing the fluid in the next couple of days at the latest. All else is guesswork, including the "codes". For example, I have a 91 or 92 rear in my 83 car right now, with 3.73 gears; the "codes" won't tell you that.

SSC

Not always and yes both can spin the same way even on an open diff.

thfirewithin

iTrader: (1)

What causes my FB to only peel out one one tire under heavy acceleration?

//<86TA>\\

iTrader: (14)

an open rear...