3.9 fd vs 4.1.1 fd

[Supafli786]

Hi everyone... Which would be a better final drive in terms of power and everyday driving? I have a 3.9 fd with a 4.1.1 tranny .. Could change the box or tranny depends which will be better for performance?Its on a 97 Gt sedan>. Thank you ..

[mike-tracy]

4.11 would provide more mechanical advantage. You shouldn't be driving with a different ratio rear diff than the front, you'll blow up your tranny pretty quick. Your freeway RPM's will be higher with a 4.11 (or 4.44) gear ratio, and your fuel economy will suffer a little, but you'll accelerate faster.

[Supafli786]

Hi not sure if i understand this part " would provide more mechanical advantage".So overall the better fd is a 4.1.1..the reason i used a different ratio tranny to diff..i bought a tranny from a guy who thought the tranny came of a Scoobie GT very same to mine but only after putting it in and drove the car i could feel a vibration occasionally ..So spoke to him & he said that it was from a jdm spec.. Thank you for your help...Please point in the correct direction of a quick GT..much appreciated..

[rougeben83]

4.11 is a shorter gearing, you lose a little top speed so you can have better acceleration.

[Supafli786]

Thank you..i have an occasional vibration maybe after 20 km...not sure what the cause of that..Help please????

[Supafli786]

tranny code - ty752vb111..Please let me know what is the fd on this Tranny?

[ouch1011]

The 4.11 (which is what you should already have) offers a little better acceleration because it will give you a little more torque to the wheels in each gear. The 3.9 is a little better for daily driving in my opinion, especially if you drive at highway speeds a lot, because it will reduce your engine speed when crusing, resulting in less engine wear and lower fuel consumption.

[jey]

Thank you..i have an occasional vibration maybe after 20 km...not sure what the cause of that..Help please????

Is the vibration felt in the steering wheel? Does it happen in all gears?