Hi guys,

What would the advantage/disadvantage of putting a 3.90, in a 5speed instead of using the 4.10.

4rotors

 

high top end speed/gear, faster acceleration if you have enough torque (im talking V8 type hehe). its just a lower gear

Final Drive RPM
5th gear @
60mph Speed (mph)
7500rpm
1st gear Speed(mph)
7500rpm
2nd gear Speed(mph)
7500rpm
3rd gear Speed(mph)
7500rpm
4th gear Speed(mph)
7500rpm
5th gear
3.90 2375 39 68 98 137 191
4.10 2500 37 65 94 131 182
4.30 2625 36 62 89 124 173

taken from http://www.rx7.com/store/rx7/fddrivetrain_rearend.html

 

these are all theoretical numbers though. Most 3rd Gens lack the power to actually get to the end of 5th gear. In our case, it would provide little, if any advantage.

 

torque?

 

haha who said we could ever use all that gearing???

 

How about with 400 rwhp and 100 to 200 lbs lighter.


4rotors

 

I know of very few cars that can actually reach the 180mph end of the speedometer. I say, why don't you take your car with that much power and top it out somewhere safe. If you reach the end of 5th in the stock 4.10, THEN you can consider changing out your rear end. Only 7's I know that can make it to speeds of near 200mph and farther are 3/4 rotors and purpose built top speed cars such as racing beat's.

 

Anyone know where I can find a write up of how to change the ring and pinion?

 

The factory service manual

Sarcasm out of the way,... try here..

http://iluvmyrx7.com/