Yesterday i was driving my car with my friend and he wanted me to do a burnout, so i did. While i was doing i could feel that my drivers side wheel was not spinning and sure enough when i turned around to look at the strip i just layed down there was only one tire mark. Since then i have spun the tires a couple of times and still the same thing. Before that happened both tires would always spin. What could possibly cause this problem? there dosent seem to be any thing noticibly wrong, the car drives fine.

 

In your case, I would say to many BURNOUTS.

 

I dont think its from doing to many burnouts, i dont go overboard and do them every day, the unit is only 2 years old and worked fine untill the day it stopped working.

 

Brake torqueing or brake standing is bad for posi units. If one of your rear brakes is stronger than the other (which happens alot on third gens) it wears the posi out real fast. If you want to make a smoke show, just fling the back end around and do some donuts, easier on the posi and it looks a ton cooler . But either way I would say your posi is toast.

 

I would say service the rearend. Change the fluid and add the posi additive if needed. I do ALOT of burnouts and whatnot with my IROC-Z, posi is still going strong but I dont expect it to last forever.

 

What makes you think it had a posi in the first place?

And don't answer "it used to put down 2 stripes", because that's not proof. Or even very good evidence. Lots of cars will do that at least some of the time, all that's required is that the tires get approximately equal traction.

Most likely, the reason it isn't acting like a posi, is because it doesn't have one. There were very few posi units around in the early years of these cars. There's a whole lot more people with the early 80s cars that think they have one, than actually do.

Take off the cover and look at what's inside. Nothing else matters. Either the parts are there, or they're not; and if they're there, they're either working, or they're not. Only way to know if they're there, is to look. Only way to fix them if they're not, starts with take off the cover.

Now.... since you suspect your rear is messed up, what's the first thing you should do about it? It would be, take off the cover and look, see if something's torn up.

And of course, from time to time, you should be changing the fluid. And how do you change the fluid? You guessed it, you take off the cover. While you're doing the maintenance that should already have been done, look at the carrier and see if it's a posi.

Besides all that, did I mention it's a good idea to take off the cover and look at what's in there? A side benefit is, if you do that, you can even count the gear teeth, and spare the world yet another "what gear do I have" post.

 

he said it was only 2 years old. I would take a guess that it was replaced 2 years ago


doing donuts is very bad!! don't listen. a 10 bolt is the worst rear in our cars to do that to. ever see a c-clip fall out on a 10 bolt? if you have drum brakes you will see you axle walk right out.

the 9 bolt can handle this better as there are no c-clips but, still? you are grabbing traction off and on very quickly. somethings will give.

I'm not saying don't have fun just expect thigs to break if you do

 

Sure, he said something about "unit" (uh-huh-huh-huh---uh-huh- you said unit) but he also didn't tell us what "unit" was replaced, or what it was replaced with.

These would be relatively critical pieces of data.

Most people who buy a posi carrier and replace it with knowledge and understanding of what they're doing (or paying someone else to do), know afterwards even if not beforehand that it's called a "carrier" or "differential" and not generally a "unit"; and they might often refer to their Auburn or Eaton or whatever by mfr or model when talking about it, rather than as "the unit". Which makes me suspect that no matter what whatever was replaced with, he doesn't know what it is/was.

What if all that happened was, he went to the junkyard and got a whole other 3rd member (uh-huh-huh now I said "member") and stuck that in the car without opening the cover?

The correct answer in any case, even if the exact make & model of the new "unit" is known, is to pop the cover and look at it. We can all sit here and type stupid crap all day long, but that won't install a pois in his rear end if he doesn't have one, or fix a broken one if he does.

And of course, stop abusing the car; or expect that if it's abused, occasional parts destruction and maintenance are to be expected.

 

well all this talk about members and units has me a little disturbed but, I will agree with the breaking parts and learing how to service your car (not saying or implying that he does not but, fact is most people don't and think stuff is cheap junk because they broke what ever on there car after treating it poorly)

 

Not to try and change the subject, but what exactly is so different about a 9-bolt and 10-bolt rear end which makes the 10 bolt so terrible in comparison? Ive never driven a third gen with a 10 bolt and both of my T/A's have had the 9-bolt 3.27, so I guess I should be thankful for that.

 

The 9-bolt has a slightly larger ring gear, and doesn't use C-clips.

There were more 9-bolts used in the various Pontiac models than in the Chevrolet ones. Firebird people (which you would appear to be one of) therefore tend to have them more than Camaro people.

They were discontinued in both car lines after 89.

I doubt you'd notice much difference driving them... other than, the 9-bolt posi tends to wear out more than the ones used in 10-bolts over the years.