I have a 97 trans am convertible with 2.73 gears. I know the car should have had 3.23's stock, but for some reason the person before me switched to 2.73's. I am looking at getting 4.10's or 3.73's. I am not sure if the gears were changed or if the whole rear end was changed. If the rear end was changed do i need a different carrier in order to put 3.73 or 4.10's in? Where can i get the gears and how much should it cost total for parts and install?

 

2.73's are a stock gear for f-bods too it dosnt make sense for him too go down a gear size are you 100% sure he did cause if he went down from the 3.23's then you have a 3 series carrier but my guess is that your car came with the 2.73's stock therefore you might have a 2 series carrier you can always check the door to see what your gears are stock to be sure,i forgot what the codes that tell you what gear came with the car so do a search for how to tell gear size or something similar to that.

 

I just recently got the car and found out that the speedometer was off. I sent the cpu to madz28 and Ion reprogrammed it and told me that from what he gathered the gears were definitley 2.73's since the tire size was correct. I got the cpu back and checked the speedometer and odometer on the highway and everything checked out. So i know the gears are 2.73's, but the since the speedometer was off i would assume they are not stock. Ion told me all trans ams with a 6spd in 97 came with 3.23 gears. So now im not sure if the gears were changed or if it is the rear end that has been swapped out. Is there anyway to tell the difference between a 2-series and a 3-series. Also Thunderracing.com has 2-series 3.73 gears, but i do not see any 3-series 2.73 gears so that leads me to belive that i would have a 2-sereis, but this is all new to me. I will check the code, which i beleive either on the door or in the glovebox and will post. Please point me in the right direction.

 

ok if you ta came with a 6 speed than it shoud definetly be 3.42 gears in that rear end with a 3 series carrier that was stock,(all 6 speeds came with 3.42 gears stock)as for telling the difference between a 2 series and a 3 series i couldnt tell you how ,and im not sure if you have a 3 series carrier you can install 2 series gears in them?mabye someone here on the board will help you out with that one.

 

Here's a question for you, is your car an A4 or an M6?! You were talking about 2.73's and 3.23's which are the factory A4 options, but in your 2nd post you said something about "...all trans-ams with a 6-speed in 97..." so I'm thinking your car is an M6? In that case, it should have had 3.42's. How are you sure what gears are in it now?

ANYWAY, to help you out, if you do in fact have 2.73's, then they are on a 2-series carrier. I don't believe there are 3-series 2.73's even built? SO, if you want to go to 3.73's or 4.10's (I recommend 4.10's) then order them for a 2-series carrier.

 

My car is a 97 Trans Am so its an M6. I checked and i was mistaken Ion did in fact tell me that all 94-97 manuals had 3.42's. I know that my car has 2.73's now because I got the speedometer programmed for 2.73's because it was off and now it records correclty. I guess i have a 2 series carrier because i don't think they made 2.73's in a 3-seiries carrier either. Is there a way to change out just the carrier or do you have to change out the whole axle. Would i be able to change to just change my 2-series carrier to a 3-series carrier? If i were to change the carrier first how much would that cost? Does anyone have 3.73's or 4.10's in a 2-series carrier? If are they reliable as far as not breaking? I am still debating on 4.10's or 3.73's if i put them in a 2-series carrier what should i get???

 

I think some people have a misconception that a 3-series carrier is "better" than a 2-series carrier? YOU DON'T NEED A 3-SERIES CARRIER!!! If you want to change the ratios, buy the (3.73 / 4.10) ring & pinion for your current 2-SERIES carrier. The ONLY difference is that the ring gear will be thicker than a 3-series would be.

And since you've got an M6, then I would definitely recommend 4.10's. That's what most guys put in their M6's.

 

So is the 2-series a 7.5" ten bolt?? Where do you measure 7.5"? Is the 10 bolt the number of bolts that holds on the differential cap???

 

Let's settle the current gear ratio question.

A4 people, put your car in 3rd.
M6 people, put your car in 4th.

Now drive at exactly 70 mph and look at your tach. The tach will tell you your axle ratio. (example 3.42's = 3420 RPM). This works with stock tire sizes.

I can't see why anybody would put 2.73's in an M6 car. Especially the later models. It's ok for the 1993 models, but those ones with 2.73's had something like a 3.28 1st gear ratio and shorter overdrives.

 

Yea like captan pete said one really isn't any better than the other. Just a little difference of thickness of the ring gear--which won't effect durability at all. I am not sure they make 4.10's for a series 2 carrier but if they do that would be the route to go.....way easier than swithcing the posi out.......but if you decide to go to a 3 series carrier send me your old posi...........i am in need of one I'll run 3.73's on it

 

Yes (well, technically 7.625" / 7-5/8").
It's the inside diameter of the ring gear.
No, that's just a coincidence. The ring gear is held on by 10 bolts; that's where they get "10-bolt" from. A 12-bolt has 12 bolts holding the ring gear onto the carrier. Someone correct me if I'm wrong. I think there were actually old style "12-bolts" built that only had 10 bolts holding the cover on.

If you put a 2-series carrier and a 3-series carrier side-by-side, they look exactly the same. The only difference is that (looking from the back of the car) the face where the ring gear bolts to is about ~1/4" to the left on a 2-series carrier compared to where it would be on a 3-series. That is just to accommodate larger pinion gears commonly used on higher ratio gears (3.08's down to 2.73's).

Kapeesh??

 

There are only two reasons why someone would switch over the 3.42 rear for a 2.73 that I can think of. One, maybe he thought the rev's were too high or something and wanted a more top end and rpm efficient rear(why he would do this I don't know, but it is possible). Two, maybe he blew up the stocker and in a quick last ditch effort had to install a 2.73 to get him back on the road. The second seems more plausable. If it is indeed 2.73, which it seems to be. Yes you need a 2 series carrier unless you convert to a 3 series, either will be just fine though. Also I know they make up to 3.73's in a 2 series carrier, not sure if they have 4.10's, easy to find out though. Good luck.

 

Ok i got it...thank you all for your responses. Im leaning towards 3.73 2-series gears for some good torque along with some reasonable highway rpm's. Im thinking of getting Strange Engineering Pro Street gears from Thunder racing.com or Richmond Gears these are the only two i have found with 3.73's in a 2-series. Opinions???

 

I had Richmond 3.73's before and they whined pretty bad, but I've now got Richmond 4.10's and they're almost as quiet as the factory 2.73's. My buddy also has Richmond 3.73's in his '95, and while they whine a little, they're really not that bad at all (nothing a cat-back exhaust and/or stereo can't drown out!).

 

How about the Strange Engineering Pro Street Gears? Anyone have any comments about them? Also have you guys put them in yourself or did you take it to a shop. Ive been told that it is a job to be taken to a mechanice because of precise alignment issues. If you do it yourself do you risk breaking the gears in a short amount of time after install?