Gear?

mob said:

damn, well that might not be impossible u can take 2nd gear up to like 80, well not sure if anyone else can but i have wasent the best idea and will never do it again but its not impossible

Click to expand...

...about 60-65 w/ stock gears if you push it. (id know, i drive stupid)

i believe my old 3.27's i could get around 70 in 2nd.

you guys think about going into 5th at the strip? oh no.

Never even consider going into 5th....with any gear. If you ever need to go into 5th, then get a taller tire or a taller gear.

maverick0716 said:

Never even consider going into 5th....with any gear. If you ever need to go into 5th, then get a taller tire or a taller gear.

Click to expand...

yep, that is what i was getting at. big nono

To get the most work out of the engine, you want keep the engine between the torque peak and the power peak with each shift, and you want a rear gear such that you cross the line right at the power peak in 4th gear. What that will mean for most mildly modded naturally aspirated Stangs is a 4.10 or 4.30 gear with tires in the 26" diameter range. Of course, for the street you may not want that much gear. And to take full advantage of it, you'll need DR or slicks, and some suspension work.

Ideally, you'll spend some time at the dyno, and find out at what rpm your torque peak and your power peak occur. Based on that info, and with the first four gear ratios of your T-5, you can calculate what rpm to shift each gear at. If you shift so that you drop back to within a couple hundred rpm of the torque peak (for most naturally aspirated engines with T-5's), you'll find that the shift point will drop by a couple hundred rpm for each higher gear. That may seem counterintuitive, but it will get the most out of your engine. My torque peak occurs at 3800, my power peak at 4900. Here's the calculation for the ratios in my T-5Z:

1st gear – 2.95
2nd gear – 1.94
3rd gear – 1.34
4th gear – 1.00
5th gear - .63

Speed drop from 1 –2 -- .657
Speed drop from 2-3 -- .691
Speed drop from 3-4 -- .746
Speed drop from 4-5 -- .63

1 to 2 shift at 5500 drops rpm in second to 3613
2 to 3 shift at 5300 drops rpm in third to 3662
3 to 4 shift at 4900 drops rpm in fourth to 3655
4 to 5 shift at 5500 drops rpm in fifth to 3465

And, as others have said, you don't want to gear it so that you have to shift into 5th because of that long gear ratio. Unless of course you've changed trannies or 5th gear ratios so that your 5th is much closer to 4th. Ideal would be a 5th gear ratio of about .85 (instead of our usual .63 or .68) -- then you could gear the car with 4.30's or 4.56's and use 5th gear too.

Go to this website (http://www.smokemup.com/auto_math/index.php?sid=12365f9b4ed493dd8b1a6025ec875aac), select "speed for rpm range comparing rear gears) and plug your car's numbers in - you can figure out what speeds/rpm correspond to what tire height and rear gear ratio. I plugged in my data below.

Transmission Ratios:
1st: 2.95 2nd: 1.94 3rd: 1.34 4th: 1 5th: 0.63

Tire Diameter 1: 24.85 inches
Rear Gear Ratio 1: 3.73:1
MPH
RPM 1st 2nd 3rd 4th 5th 6th
1000 7 10 15 20 31 0
1500 10 15 22 30 47 0
2000 13 20 30 40 63 0
2500 17 26 37 50 79 0
3000 20 31 44 59 94 0
3500 24 36 52 69 110 0
4000 27 41 59 79 126 0
4500 30 46 67 89 142 0
5000 34 51 74 99 157 0
5500 37 56 81 109 173 0
6000 40 61 89 119 189 0
6500 44 66 96 129 204 0
7000 47 72 104 139 220 0
7500 50 77 111 149 236 0
8000 54 82 118 159 252 0

I cross the line at 6000 rpm in 4th gear, with 26" tires and 3.73's. Its Ideal for me.

Keep in mind - how much power you have, and how effectively you put it to the ground has an impact on all this too.

Hmm.. i have 3.55's, and when shifting at around 5500 into 2nd, and about 5200 into 3rd, I always cross the line at the very top of 3rd. I have never hit 4th gear in the 1320. Is this possible with 3.55s? Do I not even have 3.55s? The guy I bought the car from a year and a half ago told me it has 3.55s, but I haven't actually jacked the car up to mark the driveshaft and check it out.