Saturn S-Series 5th Gear Swap

[cfg83]

jasonm -

Originally Posted by jasonm

On a RWD car, should you be able to get similar gains by switching the final drive ratio?

ie, on a 240sx, would changing the final drive from 4.08 to 3.54 have a significant impact, assuming no other changes?

I would say yes, but it will effect *all* your gears.

Here is my gear ratio comparison :

Dividing ratios : 0.730 / 0.605 = 1.2066 => ~21% reduction in RPMs

Here is your final drive comparison :
Dividing ratios : 4.08 / 3.54 = 1.1524 => ~15% reduction in RPMs

I don't know if I would want that. For me, my "ace in the hole" is my lower gears.

But, if I wasn't in an urban environment, maybe I would have a different POV.

CarloSW2

[scubascooby]

I was pondering a 5th gear ratio swap on the Impreza Sport by using the 5th from a Turbo (WRX). This would change the gearing from about 21mph/1000rpm to about 24mph/1000rpm

A typical 75-85mph motorway cruise would then be at 3100-3500 rpm instead of 3500-4000. No doubt it would slow acceleration on steeper inclines and require a drop to 4th.

The ratio swap would be no easy task on the Impreza, so it's well beyond my tools and time.

I have all ready increased the tyres from 205/50R16 to 205/55R16 to raise all the ratios slightly plus the speedo doesn't over-read by as much as before. There was no obvious change in economy because the odometer doesn't know of the change.

[TimRogers]

Originally Posted by klrv6

Does anybody know of 5th gear changes or parts that would be availalbe for a 2002 nissan sentra XE, 5spd 1.8 base model. Yes, I just picked it up to allow the semi-retirement of the suburban

I asked in some other forums and nobody had a clue.

The 5th gear in your car is 0.733, which is the tallest 5th gear that Nissan puts in a 5 speed with a 4 cylinder engine.
The options for you are therefore (possibly):
Swap in the 6 speed from a 2002 or later Sentra SE-R Spec-V and I don't know if that would be a direct drop-in. I know that to mate this transmission to the older SR20DE motors and the chassis they came in takes a lot of sourcing of additional parts. You might check out the SR20 Forum or Nissan Forums | Infiniti Forums by NICOclub.com, the original Nissan Forum for true enthusiasts. for more info.
If you wanted to change the final drive ratio from your current 4.437 to a taller 4.058 from a '91 to '93 Infinity G20 or a 4.176 from any car that came with the SR20DE motor, that could be a possibility as well.

[fairdinkumfrankies]

Can anyone help with a fifth gear change for a 1994 Geo Prizm? I have been able to reach 42mpg under ideal conditions (flat ground, 55mph, non-Winter seasons, and no traffic to consider). I am expecting to do a 100 mile commute for a few months increasing my present trip by 5X. Most of the driving will be highway so I thought a gear change to my 5-speed might improve my 38.5mpg average. I would love to be able to reach a repeatable 45mpg average without insighting road rage in fast New England/Boston 70mph traffic. My wife said she did not want me to do extensive aero mods and my budget is very modest. I do have access to a mechanic friend and I like the lowered suspension and the belly pan.

My first post,

Neal