3.90's dammit!

[combatstang]

I really really wantthem.. im just worried that i will lose everyrace on the street because of traction.. now i have the 315 nittos... i only have bad traction in 1st when cooled


BADASS03SVT ... convince me...

but also tell me.. this

1. will it cause more wear/tear on motor?
2. will it improve my et/mph at all?
3. gas mileage?

4. how do gears exactly help?

Thanks

Marc

 

[Bob Cosby]

1) Slightly, but unless you dog the car all the time, not significantly
2) Yes, if you can get traction
3) Similar to stock - unless you dog the car more
4) They multiply torque

 

[postban]

I did 373's in my live axle vert, barely noticed any difference, shoulda went 390 or 410.

Just do it and never look back. My next gear change will be 390's

 

[BADASS03SVT]

do them!!!

why buy an 03 cobra if u care about mileage..lol. seriously though u ownt notice a change. acceleration will improve...2nd form 55 is SWEET....3rd on the highway ROCKS...ask my girl... :rockon:

i wouldnt worry about traction with the nitto's. dropping 2nd and peddling it fo rme itll be ok.....1st is a waste on regular tires though

 

[IronTerp]

4. how do gears exactly help?

Back in the day, a gear change was the end all, be all to performance mods (along with headers!!). Great bang for your buck mod back then. But now, with these high horsepower cars that already have tons of torque, it's become a little more of a "designer" mod....especially when you take into consideration the IRS and inherent traction challenges.

Lower gears (higher number) multiply the torque that your motor is producing at a faster rate. For every crank revolution, the rear tires will be turning that much faster with lower gears. Thus, you will go from 2,500 to 6,000 rpm much quicker. I was running 3.42's in a 71 Trans Am a few years (decades!) back and went with 4.10's and couldn't believe the acceleration difference.

The drawbacks, obviously, are running out of rpm in 4th gear (most of the guys are running taller tires to compensate for this, which just brings the net ratio back down again.....???), getting good traction off the line, and lastly, a little gas mileage. But, the overdrive tranny's really help with gas mileage now and it's not much of an issue. I took the 71 TA to the Street Machine Nationals back in Indianapolis back in the 70's and actually did a complete drum to drum swap from my 4.10's to another rear with 2.73's. Without overdrive back then, I would of had to drive at 45 mph and still gotten 10 mpg. As it turned out I drove at 65 and got 20 mpg!!!! But the swap was kind of a PIA........

 

[combatstang]

they are being installed right now.. i will let u guys knw..

Marc

 

[CobraZb]

Are 3.90's safe for the IRS?

 

[red03dave]

Are 3.90's safe for the IRS?

YES. I had 4.10's in my last 03 and LOVED THEM. Now that I have the KB I'm staying with the 3.55's so that I don't run outta gear at the track. I hope to have an auto in it before long as well .. .