please answer my 3.08 to 3.42 gear change question

[99firebirdconv.]

if i were to change my stock 3.08's with 3.42's what would be the gas milage difference, would it be a lot harder on gas and would it rev way higher??

[Only4U]

i just answered your question in gen tech.

[Dominic]

You would notice an increase in fuel economy by about 1-2mpg around town because it would be easier to take off from lights on the engine, and you would probably not notice a decrease one bit on the highway. I find the 3.42s are perfect all around gears for the V6's, I don't understand why they chose 3.08s for most of them...

[99firebirdconv.]

Domonic, well if i change my gears i have to lose gas milage on the highway cuz it will be reving higher right. It just dont know how much gas milage i will lose, also i was wondering if you knew how long an installation of gears would take, i just dont want to get over charged on labour.

[Only4U]

heh, you won't lose that much mileage, if any...take my word on this, the extra 100-200 rpms you make on the highway won't make that much of a difference.

it's hard to say how long an installation such as that will take. i wouldn't go by time i'd go by price...it will cost ya anything around $250-400 depending on where ya go.

[DominusEtDeusNatus]

Last tank I got 25mpg and on the highway I cruise at 3K to 3.5K. That's with 4.10s so let's stop the fuel economy myth. This tank I will force myself not to race just to get a "normal driving" number.

[NSolano]

i just read some other posts on this board and they sya that if you get 3.42's on your car u have to do all this reprogramming to get the rpms and speedometer to be accurate, ist his true?? i thougth you only had to get the gears installed and thats it.

[Only4U]

nope that is not it at all...check back in drivetrain for about the last couple of days and you'll find a whole lotta talk about the pcm stuff--you should find the info you need in there.