Options to Replace the 2.73 on 1997 Z28
 

I have an auto 1997 Z28 which comes with the 2.73 rear end (I believe this was the only rear end option for autos)

Anyway, I have a G2 intake (not cold air) K and N Air Filter, and Borla Exhaust. Everything else Performance related is stock. I want more 0-60 Speed, and I was thinking that changing to a higher ratio would make the most difference for the price. What are my options as far as Higher Gear Ratios, and what are your opinions??? I understand a higher gear ratio lowers your top end speed, but by how much? Lets says with my 2.73 my top speed is 160 MPH, with 3.73 what would it lower the top speed too?

Also, what are the Best Under $300 Performance upgrades for the LT-1?

Re: Options to Replace the 2.73 on 1997 Z28
 

3.08
3.23
3.42
3.73
4.10
4.56

Top speed isn't so much about lower gear ratios as it is about engine rpm vs mph. In an ideal setup you'd want your top speed to occur at peak hp. w/2.73s you'll be at 4k rpms at 160, whereas w/ 3.73s you'll be at 5500. Try messing around on here for awhile so you can see what you'd prefer. 3.73 is generally considered the best setup for an auto.

Re: Options to Replace the 2.73 on 1997 Z28
 

Some of the autos came from the factory with 3.23 gears (GU5). Yes gears would definitely help your 0-60 time. Most auto guys go with 3.42's or 3.73's. Since you have 2.73's you will need to get gears that are made for a 2 series carrier. Whether you run 3.42's or 3.73's really just depends on personal preference based mostly on how much highway driving you do.

Re: Options to Replace the 2.73 on 1997 Z28
 

How Much would 3.42 or 3.73 gears cost? How Much Would a Garage Cost to Change them for you?

Is this a job the average person with mid-range automotive knowledge could do???

How Big of a drop in 0-60 Time would i see?

Re: Options to Replace the 2.73 on 1997 Z28
 

I believe it cost me $250 in labor at a local rear-end specialist shop. And No, this is not the easiest of projects to take on when it comes to installation. I am not saying that you can't install them yourself it's just that most people choose to leave this to the professionals.

Re: Options to Replace the 2.73 on 1997 Z28
 

How Will that effect my Gas mileage? With a 3.42 or a 3.73 wouldn't my car run at high RPMs??? I was talking to my teacher today who knows a lot about cars and he said putting a 3.73 in a 4 Speed auto is a Bad Idea. He also said something about a Torque Converter.... what is that and what does it do???

This kid at my school has a 2003 Infiniti G35 and he wants to race me. These gears will def help that too.

Re: Options to Replace the 2.73 on 1997 Z28
 

3:73's are perfect for you auto.. Trust us.. I loved them in my when it was an auto.. :D As for gas mileage, i still got over 300 on long trips.. Around town was around 250.. RPM's at 80 where around 2500 ( i think correct me it i am wrong guys, been awhile. Use to my T-56 now ) As for you Torque Converter, it will be just fine as well..

Re: Options to Replace the 2.73 on 1997 Z28
 

http://cgi.ebay.com/ebaymotors/82-02...spagenameZWDVW

How do those look??? Good price???

I have a 2 series carrier, so i would need a ring gear spacer.... where can I find one of those and how much do they cost??? Would my local parts store carry it?

Re: Options to Replace the 2.73 on 1997 Z28
 

I have 3.73 gears and the spacer ring that I was going to use on my car that I can sell you... I haven't attempted to list them anywhere yet, but they are used. About 3K miles on them, but they are in good shape. I can take pics when I get home if you would like. I paid $135 for both parts (gears and spacer), so I really would like to get at least that, and maybe a little for shipping. Let me know what you think...


*** EDIT ***
The reason I am not using these are because my posi is going out and I decided to go with a complete aftermarket rear. I just now need to save up for it...

Re: Options to Replace the 2.73 on 1997 Z28
 

3.23s were a $300 option on auto cars in 97.
Switching to 3.73s would be fine for you. The best way to do the change (you'll also need a 3-series carrier) is to drop the rearend from the car.

Re: Options to Replace the 2.73 on 1997 Z28
 

For a 97 auto I agree 3.73's are excellent. I installed Strange 3.73's in my 96 WS6 {stock ratio for A4 WS6} and was very happy with that choice.
If your low on $ and want the stock 3 series carrier and 3.23 gears I took out of mine, I'll sell these parts for $50 + shipping. The stock carrier had started to slip so it will need new cones. The gears are original GM 3.23's with 30k miles and in excellent shape.
PM me if interested although I'll be leaving for a few weeks Monday, but I can get them packaged and let my grandfather send them to you if you want.
Although, as I mentioned, and if you have the $, 3.73 gears are available to fit a 2 series carrier from several manufacturers, including Strange, which will not require the spacer. And after building a few of these units, IMO; seeing as how the 10 bolt 7.625 rearend gears are a weak point already in an LT1 F-body, no matter what brand gear is used, I don't suggest using a spacer to adapt 3 series gears to a 2 series carrier.
Parts for sale thread for my gears / carrier here.

Re: Options to Replace the 2.73 on 1997 Z28
 

That "rearend" would include the carrier and pinion shaft only, correct? Usually, everyone refers to rearend as being the rear axle assembly, which will not need to be dropped for any gear or carrier change. Just making sure. :)

Re: Options to Replace the 2.73 on 1997 Z28
 

As for the used gears; some people do not recommend it but others say it fine as long as they are matched. To me, used gears aren't worth too much but that's just me. $75 plus shipping is a little high imo. A local junk yard can probably beat that price.

You can call one of the guys at http://drivetrain.com and talk with them (I did) and get a good price and free advice. A spacer with bolts should be about $50. If you buy used gears, a spacer and pay a competent garage to install the spacer and gears you will probably be looking to spend about $350 to $400. A good garage will be able to do the shopping for you.

If you have an automatic the spacer isn't going to be a problem as long as you don't go high power or drag slicks. The word out is if you have a manual transmission, even street pounding will eventually break that type of a setup.

Re: Options to Replace the 2.73 on 1997 Z28
 

I guess it is good that the M6 cars came with a 3 series carrier then :D

Bowen292, my offer still stands but price is a little negotiable... Hit me up on PM if your interested...

Re: Options to Replace the 2.73 on 1997 Z28
 

how do i know if i have a series 3 or 2 carrier, and would the 373s be rougher ont he rear end and tranny?