How do I find out what gears I have in my 9 bolt, no tag on cover? Any help would be great.

 

If you are correct that you do have a 9-bolt and have 305 & t5 the ratio should be 3:45.

 

I have an 89 firebird formula WS6, with T-5, and 9bolt. The car was damaged before I bought it. The drivers side axle shaft is bent and I couldn't find a replacement. so I put in a 10 bolt, and am parting out the posi disc braked 9bolt. Any one need b parts?

 

my car was a 305 t5 and it has 3.08 and drum brakes in the rear and its a 9bolt

 

Can I count the teeth of the gears to figure out wich ones I have. There has got to be some way to figure this out. I'm selling this setup, so I need to find out wich ones I have. Any help would be great.

 

Yes.

 

Okay then how? ring gear, and pinion gear. Whats the formula????????????????????

 

# on ring, divided by # on pinion... for instance, if you count 13 and 40, 40/13 = 3.076923076923076923 etc. commonly known as 3.08

 

The ratio should be stamped onto the ring gear as well if they are OEM gears.

 

Only 9-bolt gears available in 1989 for his 305 TPI & T5 was the 3:45 ratio and I dought anybody would change those. But if he wants to pull the cover so be it.

 

I agree that changing the gears is unlikely, but changing the whole rear is a very very common practice. I.e. the 3.70 posi/disc 9-bolt in the back of my '91 RS. Who knows what was done before he got the car?

Pull the cover and count.....it's the only way to really be sure.

 

Is anybody reading what model car and engine & tranny plus a 9-bolt rear this question is about???

 

The issue is not what came in the car; that's not necessarily the same thing as what's in the car now.

Sooner or later somebody's going to ask him for his gears. And I can guarantee that if he tells them it has 3.45s and just pulls them and ships them, and they turn out to be 2.77s (because somebody "upgraded" to a 350 rear end somewhere along the line) after the parts arrive, there's going to be a real unhappy buyer out there.

Much wiser to go ahead and look, and assume nothing.

 

It's the original rear end. I'm the third owner. The car is an 89 Firebird Formnula with a TPI 305, T-5, 9 bolt posi, with pbr disk brakes. It was originaly a Canadian car. Thanks for the info, I'm going to count teeth in the morning. And yes I'm parting out my 9 bolt.

 

Those 2 statements don't belong in the same sentence, about the same car. Sometimes even the original owner doesn't even realize the rear has been swapped; especially not if it was "repaired" under warranty. Basically a subsequent owner no way whatsoever of knowing any of that.

It's still important to count the teeth, to avoid screwing over somebody that buys the stuff.

 

Agreed. Pulling off the cover only takes five minutes and its the only way to be sure.

 

I checked the side of the ring gear and it say's 3.27, and I also counted the ring gear teeth at 36, and the pinion gear teeth at 11, and came up with 3.27. I am the third registered owner. The father of the family I bought it from was 1st owner, his son was 2nd owner, my father in law was 3rd owner, and I'm the fourth. There has nevewr been any rear end work done to the car, other than my swapping out the 9 bolt for a 10 bolt, cause I can't find parts.

 

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