what is the difference between 3.42's and 3.23's gears?

3.42's will feel slightly better then the 3.23's. Generally the higher the number (lower the gear ration) the faster it gets you off the line, the lower the number (higher gear ratio) it will be better for top speed runs. What is your purpose for the change? What are your goals for the car?

-Jim

well i just found out that i actually have 2.73 right now. i am working my way towards a nice street/strip car, that will spend most of its time on the street, since the nearest track is about an hour and a half away.

I take it the car is auto then since you have 2.73's. Usually the best gear for an auto car is a 3.73. You should see a large differece in the way the car feels with them.

-Jim

yeah if you switch from 2.73's to 3.73's, it'll feel like your car just gained about 100 more horsepower And another big difference you'll notice for sure will be your gas mileage haha!

I love that lol, i'm, not knocking you or anything but i really find it funny when someone talks about gas mileage and performance cars. I never even look at my gas mileage, I drive my cars because they fun to drive. If I wanted gas mileage I'd drive a 4cyl. i measure my car in smiles (evil grins) per gallon

-Jim

Jim with the way gas prices are now and the way they seem to be heading, even if you or he bought your car for the smile value, unless you've got a really good paying job or have a bottomless wallet, gas mileage does have to put into the equation whether any of us like it or not.

As for gears, since you plan on driving it more on the street then at the track, I'd go with 3.42s. They're a good bang for the buck, while still not hurting your gas mileage too much but still giving you the added "oomph" you'd want at the track. If you'd plan on your car being the other way around, more strip then street, I'd say go for it with the 3.73s. But that's just my opinion.

I have a decent paying job, but right now i'm still single and don't have many bills I easily spend $150 every two weeks in gas between the three cars all 93 octane. I really don't worry about gas mileage at all, i think my monte may get 7 mpg lol, with the new motor maybe 5. In the future when it does become a concern to me, i'll just get a beater and save these cars for the weekends or cruising. I just think a perfromance car should be just that, gas mileage would never be a concern with me in comparing them, these cars are meant to be fast not frugal.

-Jim

That's cool that you've got a decent paying job, are single and don't have many bills Jim, but some of us are in different situations and do have to watch our pennies even though we enjoy fast cars. Also if it's done right you can have our cars both be fast and still "frugal". I've managed to do it with both my 4th gens (both get around 28-30mpg on the highway/22-25mpg city) and I can tell you there's nothing really stock left on my 99 besides the heads and my 97 isn't far behind it.

Oh and another thing, some of us can't afford to have a beater (this coming from someone with 4 of these cars), so we've got to give members options of different things so that they can make the best choices for their life situations as well as their financial situations.

i am in the same kind of boat you are sue. i don't have the best paying job, and now i have to take summer classes, which cuts back on my hours during the summer even more! i do have a beater car for the winter, but its not super on gas either. so i do need to watch my mpg's because it does matter for me. will the 3.42's be fine in my stock rear end? i know it's not the best rear end, but i have read that people have put 3.42's and even 4.10's in them.

If you are going to go with 3.42's I would just try and find a stock rear. The local f-body yard here sells them for $300 with brakes and alum covers (98-02 ss/firehawk rears). That's alot cheaper then buying the gears/install kit and installation.

-Jim

What if a 95 Trans am came with an Auburn posi rear end with ABS, then you switch over to an Eaton locking type style? Would the sensors prevent the car from accelerating?

Skittles,

I had 3.42s in my car and on long trips got almost 32 mpg at 75 mph! I really don't think you will notice too much in the way of a mpg loss with the change in gear ratio. Check F-body.org and look up their gearing chart, it will tell you exactly what rpms your car will turn on the hwy. Don't forget, when the gear ratio is changed, you must also mod the computer program a bit, becuz it is set up for the 3.23's. pcmforless.com can do that for you, or a Hypertech Power Programmer can also do it.

I also had the 3.42's in my car and I didn't notice a huge loss in MPG but it sure added to the seat of your pants feel and spins the tires at will. I still have the original ring and pinion that camin the car. they say 3.42 right on them. When I first bought the car I thought I had 3.23's

I f doing gears i would have them installed proffesionally with a master install kit. Then you don't have to drop the entire rear just open it up and thave them installed.

Usually for a street car an automatic likes 3.73's and with a 6 speed manual 4.11's

http://www.edmunds.com/used/1994/pontiac/f...ktid=ik16231731

That is a link to the specs for a 94 new they got 17/25 MPG for a manual and 17/24 for an automatic

32 is great. I haven't heard of anyone getting over 30MPG in one of these even with porting and polishing and very efficient breathing so that is great milage you got. Was there a real strong tail wind and was the trip all downhill? (kidding)

I am totaly kidding depending on what specification book you look at highway milage for a formula coupe is as high as 28MPG so you gained 4MPG still very good.

Doug