another gear question

[Joshta]

Sorry to post this but i couldn't find what i wanted in the search engine. I will be doing a gear swap shortly in an 02 GT auto. i am deciding between 3.90 and 4.10's. assuming i get rid of the speed limiter, does anyone know about what i can expect in top speed? according to calculators, 0-60 falls nicely in the powerband of 2nd but i don't really want to hit O/D in the 1/4 mile. If anyone can help or reassure me that i'll be happy, it would be appreciated.

[SkylineUSA]

What is the tranny gears? How tall is your back tires? There are calculators on the net that you can use, like this one www.speedworldmotorplex.com/calc.htm

[Joshta]

thanks, that's the best one i've seen yet. my tires are 245/45/17 and the tranny is 1:1 in 3rd and .7:1 in 4th. what's so odd is that it shows that i have 3.73's. the people i bought it from said it was completely stock and it shifts out of gear at just over the mph of what my old v6 did (because of the extented redline), but i know my 6 was stock. I'm gonna try to get in touch with the people and find out.

Still if anyone has any personal answers they would be appreciated.

[SkylineUSA]

I would keep the 3.73, but thats me.

[giddyup50]

If you didn't already have 3.73's I would get 4.10's. Since you have the 3.73's now it wouldn't be worth the money to get 4.10's. Listen to Sky, he's the car God!!!

[Joshta]

well, i did get in touch with them and they said that it was stock. they did put in some white face 150 gauges which redline @ 5900, but in gear it runs to 6200. if that's not right and it's some roush gauge, that could be it.

[Joshta]

i know it, damn conspiracy is what it is.

[SkylineUSA]

Stock tachs are never right.

You can mark your tire, and do one complete revolution, count how many times your axle rotates, and that will be your gear ratio. If you want to make sure.

[vw_man]

I have a question, I have a 97 GT with 315/35/18 on the rear and am clueless in the gear realm. It is about 6 miles to work and there is two stop lights so I like to have at least a little fun. I checked out the HP/Torq calculator, Awesome site. Speed Limit is recommended at 55. Recommedations on which gears to get would be greatly appreciated!

[SkylineUSA]

Need more info.

Engine mods, and what trans are you running.

For manual I like 3.55, and auto 3.73. If your building and all out race car, you can go to a numerically higher number (gear).

[vw_man]

Right now all I have is a h-pipe and exhaust, some nice spark plugs. I plan on heads, cam, pulleys, mass air flow, cold air intake. It's just a real slow process. I heard gears is a good place to start. Thanks for the input

[SkylineUSA]

If you not going to be boosting, with a manual 3.73, auto 4.10s.

[SkylineUSA]

Gear Ratio & Tire Size Chart

Good "rule of thumb" calculation is to mutiply .12 by your tire diameter. (.12 X 38" = 4.56)
(see more formulas at bottom of page) The below table can be used to get a rough idea on gear ratios. The colors represent ideal RPM's at highway speeds (65). For highway cruising and best fuel economy stay towards the yellow (2600 rpm), around town daily driving is color coded green (2800 rpm), and for better towing power or just more 4-low power use the ratios near the red (3100 rpm). These calculations are assuming a manual transmission with a 1:1 ratio. If you drive an automatic your RPMs will be slightly higher, and the opposite is true if you have overdrive (your RPMs will be slightly lower).

Better Gas Mileage Near Factory Ratio More Power

http://4lo.com/calc/geartable.htm
Gear Ratio
Crawl Ratio
P-Metric to Inch Diameter
Tire Change (find new gear ratio)
Speedometer Adjuster (with oversize tires)
(New Tire Diameter / Old Tire Diameter) * Speedometer MPH = Actual MPH Simple Gear Ratio Formula
Ring Gear Teeth Count / Pinion Gear Teeth = Gear Ratio

[vw_man]

Thanks for all your input, any brand better than the other?

[SkylineUSA]

I have really never heard any bad things about any of the gear manufactures.