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

[kerryp]

Hello Neal.

Swapping gears is fairly simple, use a tranny from a 1994 Prizm with a 7afe, 1.8 litre engine. This transaxle has a 3.73ish rear end versus your 4.33ish, for a 15% reduction in RPM's. This gets sweeter, first gear is about 15% lower, so overall, first gear remains unaffected!!! 1-2 shift might be a little more dramatic.....


BTW.

This is what I done for my 1987 MR2 project.
Was expecting 42 MPG, before I discovered this website!
Kerry

[Weather Spotter]

cfg83: I am filling in the wiki with your data and have a few questions.

Do you have a good overall cost number ($140 in parts) what was labor?

Is the ~41 to 49 MPG 20% gain at steady state a long term MPG gain?

How long did the mod take?

Regear for lower cruising RPM - EcoModder

[cfg83]

Weather Spotter -

Originally Posted by Weather Spotter

cfg83: I am filling in the wiki with your data and have a few questions.

Do you have a good overall cost number ($140 in parts) what was labor?

Is the ~41 to 49 MPG 20% gain at steady state a long term MPG gain?

How long did the mod take?

Regear for lower cruising RPM - EcoModder

I bought a *new* gear set at the Saturn parts counter, so as you read I paid about $140 for both gears. At a junk yard I would guess it's under $50. I think I paid my mechanic about $100 to do it. I think you need a new gasket and tranny oil too.

The mod took about 1 hour in an auto repair shop where you can raise the car up and have all the power toolzz to make things go fast. I'll bet an Aamco could do it fast, assuming they'd be willing (I don't trust them, BTW).

CarloSW2

[HaiRuiDe]

That is great I like the results... I am considering a SW2 for hypermiling... how many miles do you have on your engine? I can only find a few manuals in my area all with 100,000 plus miles. Is this a solid enough engine?

[cfg83]

HaiRuiDe -

Originally Posted by HaiRuiDe

That is great I like the results... I am considering a SW2 for hypermiling... how many miles do you have on your engine? I can only find a few manuals in my area all with 100,000 plus miles. Is this a solid enough engine?

Cracked 200K miles last month :

SaturnFans Forums - View Single Post - how many miles do you have on your saturn?

Originally Posted by cfg83

Hello -

Happy Daze!!!!!!!!! ...



1999 Saturn SW2 200K Miles

Couldn't have done it without youz guyz!!!!!!!

...

Do some R&D at saturnfans.com and you will see that the health of the engine depends on the previous owner (like most cars, I guess). S-Series engines burn oil. If you don't watch the oil level, you can dry out the timing chain. If the timing chain goes, the pistons will smash the valves because it's an interference engine.

IMO the best models are the "2nd gen" between 1997 and 1999.

Here is my most expensive repair, an $1100 tranny fix at 115K miles :

1999 SW2 Quill Bearing ... - SaturnFans Forums

The hardest part is finding a manual tranny in an SW#. That was *the* deciding reason I bought it used at 36K miles off a Saturn lot back in 2003.

Here are a few automatics within 200 miles of Grand Rapids, both with free carfax :

Cars for Sale: 1998 Saturn SW2 in Taylor, MI 48180: Wagon Details - 284271773 - AutoTrader.com
Cars for Sale: 1999 Saturn SW2 in Tinley Park, IL 60477: Wagon Details - 285787287 - AutoTrader.com

I am definitely emotionally attached to my mini-wagon, but if were looking for an S-Series right now, I'd be focusing on a 2nd gen SL1 or SC1, because that would be my best bet for a manual tranny, and I'd get the fuel-economy MP2 tranny for free.

CarloSW2

[thriftee]

Originally Posted by cfg83

jasonm -



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

Sorry for digging up the old thread, and thanks for posting it in the first place...

So, if you had to do it over, would you:

1. Leave it alone
2. Use the 5th from a 97- SOHC so the stretch from 4th to 5th wasn't so big
3. do it with the 5th from a 98+ SOHC as done
4. use a 97- SOHC complete trans
5. use a 98+ SOHC complete trans

??????

I'm thinking of doing this if I get an DOHC SC2, which it seems might be a better car and motor overall than the SOHC SC2 model, but would like the economy of the SOHC or better on the highway