hi everybody i have an 91 RS 305 and yes it comes stock with one wheel wonder, so the other day i went out and was doing a brake stand and i could of swore that both tires were spinning, because there was so much smoke. So i take off and come back the other way and YES there are two tire marks, at the time im thinking awsome i have posi but then im thinking maybe theres something wrong with my rear end. So i put it on ramps and no more than get under there, and right on the axle there is like a picknpull writing that says 89 firebird and a bunch of other writing .

So my Qs is i thougth the firebirds have one wheel wonder to but maybe it was a formula firebird, but it has drum brakes so is it true it has( lsd or posi or not) and dose anyone know the ratio on those rearends.

thanks ,

 

you could have it...jack the rearend up again, spin one rear tire forward...the other one should spin forward as well....if it does that, you have limited slip...i think the limited slip rearends came with like 3.08's or something....look in your console and look up your RPO codes...that will tell you if you have the limited slip option and what gearing you have....

 

Here's the RPO codes for you so you know what they mean...

GU2 - 2.73
GU4 - 3.08
GU5 - 3.23
GU6 - 3.42
GW6 - 3.27
GM3 - 3.45
GT4 - 3.73
G80 - posi
G92 - performance

 

My peg leg will spin both whenever I power brake it. I think something is bad wrong. I know I do not have posi but sometimes I do get 2 tires spinning. I figure the spider gears are on their way out.

 

pop the cover off and look. yes, drums and posi was common in the firebird and camaros



yes alot of formulas had drums and posi

doing the spin test is worthless

 

the rear end is not the stock one so will the codes work for the firebird rearend and also its not just sometimes its all the time when i gun it off the line both spin when i turn it trys to spin out alot way more than a one leger so i dotnt know i guess ill just take the cover off i should changes the diff fluid anyways but hay if i do have lsd then cool if not then its ok to as long as when im doing a burn out i can smoke both of them then its fine with me
thanks everbody

 

this is why you "pop the cover off" take a look and see what it is


there are so many guys on here who think hey spin the tire

that's foolish way to see what the rear is.........


if it is a open rear and the both spin forward then you think it's a posi? if it is a posi and you hold one wheel and try and spin the other and it spins what you think it's an open?



spring pressure in the stock 10 bolt thirdgen auborn posi units are on the tame side, add age and miles well It still is a posi just not very good one


so the only way to KNOW is to open the cover and look. plus you can see what gear ratio it is. (this will help you from hearing the "turn the whells " which does not work correctly. even if there was no way the spider gears would turn and through off the reading you still would need a better way of mesuring the specific deg. the wheel turned and the drive shaft turned right down to the perfect deg. other wise a 2.73 would look like a 3.08 or 3.08 and 3.23 and so on

 

yea there are a few tests out there to see if you maybe have posi....only way to surely tell is get your hands dirty and pop that cover off....i'm sure its all sludgy fluid and deteriated gasket that needs replacing anyways...

 

I've got an 86 camaro. The rear has a tag that says use limited slip fluid only, or something to that effect. Also I jacked the passenger side up and tried to spin the wheel. It wouldn't move at all. Now I know that these tests are generally considered worthless, and I should only go off pulling the cover, but if it wasn't posi then wouldn't the wheel spin? Also it has disc brakes all around if that means anything. I don't know what the options were for the 86 model year.