jwth2005

not to thread jack but its kinda on topic. i just bought an 06 gt. the rear diff says it has 3.55s however the rpms stay about 2450 at 70 mph with the stock 17s. Can anyone confirm this??

gman73

I have read that your car will actually dyno a little lower with 4.10s but dyno numbers are just a tool to see if your mods are working. With a manual, you just need to adjust your axle ration with our hand held tuner. No additional tuning needed. Now with an auto you will need your tune adjusted as your shift points will be different.

jahudso2

jwth - if you have a manual transmission and 235-55-17 tires, then you have 4.10s in your differential, and not 3.55s. Are you getting this speed based on your speedometer or another source such as a gps?

jwth2005

speedo havet tried a GPS yet. passed by a radar sign a week ago. speed limit was 35 and per it i was doing 34

Manual 5 spd

gman73

With the stock tires and a manual, your RPMS should be around 2100 at 70. With 4.10s your RPMS would be 2400 at 70. You might want to see if your speedodometer is off. Use a GPS to check your speed. Here is a RPM/gear calculator.

http://s197forum.com/forum/showthrea...culator&page=3

See post #53

jwth2005

yea i didnt receive a tuner or anything when i bought the car. just also found out that it has a B&M short throw shifter

808muscle

4.10s make the car feel much lighter, therefore it feels faster. A great mod imo.

jz

The easiest way to understand how 4.10's work, and why you won't see an "actual" increase in HP is to compare it to an 18 speed bike.

You being the bike rider is a constant. First run, start in "1st" gear. Second run start in "18th" gear. You are just as strong in both runs, but the multiplier has changed therefore allowing you to accelerate faster when starting in 1st gear. That's exactly how 4.10's work.

I have never once regretted my decision to go to 4.10's. I'm sure you'll be more than pleased with the end result. Whether you understand how it works or not, it'll put a smile on your face!

jwth2005

ok guys... took the car out today with my garmin. got it up to 70 mph on the garmin. Stock speedo was at 72-73 and RPMS were between 2400 and 2500... is this consistent with 4.10s? is that how much difference they make in the speedo as well??

Never2mucHP

You could always lift the rear of the car, mark the tire, and rotate the driveshaft to count the revolutions. That would give you and idea.