I have a 95 Z28 convertible and I like to just cruise the car. I like to get on it and take it to the track once and a while but mostly like to take it on cruises. I have 2 ring and pinons, 3.73 and a 3.42 gear ratios. I am running 17" wheels and its an automatic. Just wondering what anyone's opinions were?

 

I run 3.73's in my auto. But I have a heads/cam stalled auto. If you just cruise, 3.73's will just mean worse gas mileage and more wheel spin.

 

3.73's for sure.

 

3.73's no question. It will help your acceleration and the Larger wheels with the 3.73's are going to keep your speedo more accurate than the 3.42's.

If you do alot of highway driving and want gas mileage go with the 3.42's and get your speedo calibrated. You can do this with a hypertech, mail order tune, or find someone local.

Jake
Cook Performance Engines
www.cpengines.com
317-697-6061

 

Do you think that's the best choice for someone who mostly just cruises around? I burnt the tires off with 2.73's. If he is going with 3.73's I would suggest a sticky tire and some suspension mods to go with it.

 

The diameter of the wheels does not affect the speedometer. It is only affected by the diameter of the tires, and its possible to use a 17" tire with the same diameter as the stock 16" tires. The 3.73's will have a larger impact on the speedo error.

We also don't know whether his car has the 2.73's or 3.23's, but in either case the change is significant.

If you change the rear axle ratio, you have to have the PCM reprogrammed for it, no matter what size wheels you run. This is particularly true with an automatic, since the PCM uses both RPM and MPH to determine the shift points.

 

the car originally had a 2.73 gear and i put a 4.11 gear from an s10 in it now and that is way to much. Do you think that the 3.73 will be to much like the 4.11? And yes I will be getting my ecm tuned for my gear.

 

I would leave the rear axle alone. Gear swaps in my opinion are over rated for a street car.

 

Well my problem is that there is a 4.11 gear in there now and its to much. The car had a 2.73 so i was thinking more along the line of 3.42 to bring it back down.

 

Its simple math... at any speed, your RPM will drop 9.3% when you go from the 4.11's to 3.73's. If you were to go with 3.42's, your RPM would drop 16.8%.

 

He said he plans to take it to the track from time to time also, the 3.73 is the overall best gear most people agree. At 55 I am at around 2100rpm's with a 235/50/16.

And if you was burning the tires off in excess with 2.73's you either have a built engine, garbage tires or your foot is heavier than your car. I have 3.73's and I am guessing (he does not have a sig) I am driving around with a little more power than him with just LCA's and some street tires (not drag radials) and I can easily take off and not bark the tires etc. Naturally if I lay into it the tires do tend to spin in place.

 

Merging with cross-post from LT1 Based Engine Tech.

 

My engine only had a CAI and muffler delete when I had the 2.73's. And I do have a very heavy foot

But yes I agree that 3.73's are generally the best, as that's what I have in my car. They are not the best for every single situation though.

3.42's can be a good gear for an almost always street driven auto.