alasdair67

OK, I know everyone's got their own preferences, but here's the question.

What's better for an '06 GT, and why? Initially it'll be bone-stock (apart from 20" Saleens), but will eventually get a CAI, UDPs, X-pipe, aftermarket mufflers, and maybe/eventually a blower or nitrous.

3.55s
3.73s
4.10s
4.30s

One thing to perhaps bear in mind is that 60%-70% of my driving is highway mileage, but that gas is almost $6.00 a gallon here...I'm in Scotland.

While I'm here, annother (off-the-wall and probably rather newb question) question I have is this. Is it possible to switch out gears but to use a longer 5th gear to retain halfway-decent highway gas mileage? Has anyone ever done this? In case you hadn't figured it out, I want the best of both worlds.

Menace

I'm no expert in gears. All I know is that the lower the gear the higher top end, and the higher the gear the better acceleration. I think the 3.55 gear is already set up to be the "Best of both worlds." Though like I said, I'm no expert. I just wanted to say... it sucks to live in Scotland! I think Gas is finally lowering here and I've seen it to be like 2.13 for 87 Octane.

757GT

Manual or auto?

Philostang

Ouch! Alasdair, I'm sorry to hear about that gas price. I think that coupled with your anticipated use pretty much settles it for me--I'd stick with the stock 3.55s (manual). Keep in mind that the `05/`06 manual trans has a pretty tall overdrive (0.675:1 I hear), so you're already getting a nice overdrive gear for highway use.

I'm no expert, but I think the only way to get more out of this compromised combination is to get a new trans--a 6 speed would allow you to move up to 4.10s and still get away with decent highway cruising. I don't know if anyone has done that swap yet, but it's something to look into.

Good luck! (maybe take up a "Gas Fund" or something),
Best,
-j

fin1

It comes down to what your goals are. If you looking for more off-the-line acceleration, the higher gears (3.90, 4.10, 4.30) will help at a cost of reduced top-end speed per gear. Since you drive mostly on the highway, 5th gear is available and would give a good cruising RPM with a higher gear. I run the 4.10's and get 2500RPMs @ 70MPH in 5th gear.

However, if you start to talk forced induction and running the 1/4 mile, using 5th is not the best option since this is an overdrive gear. For example, at my current power level, I am close to max 4th gear without taking it deep into the redline. In fact, with my next set of changes, I'm going to step it down to 3.73 so I can get a higher MPH.

For N/A (or a moderate force induction) car that sees allot of highway time, the 3.90's or 4.10's are a good choice.

mustangman02232

a shorter gear does not always mean a higher top speed, if you dont have the power to over come the drag 2.73s would all around lower your preformance and hurt your gas milage cause you would be in it more to accelerate, im not sure what the OD ratio is but i think it was .62, but whatever it is it is very tall, however, what are the tire sizes on your 20" rims? depending on what the overall hight of that is and the OD you could probably do 4.30s, but do atleast 4.10s, 3.73 from 3.55 or 3.31 for a auto wont feel like much, and the difference in rpms is small

viking396

Myself, I'm going for 3.90 gears, good for all around use.

alasdair67

Sorry, manual. Forgot to say. Just assumed everyone else would assume I meant manual. But manual it is.