corvettedreamin

'splain this to me.

If a "ratio" is the magnitude of quantities relative to each other, then isn't 2.73 : 1 exactly 2.73 times greater than 1 and the 3.31 exactly 3.31 times greater than 1. Which means 3.31 is a HIGHER ratio and a NUMERICALLY higher value?

What am I missing?

eci

Increasing the number of shaft turns to move the wheels once has always been LOWERING the gear.

Dave07997S

I don't think 3.31's are enough gear. I would probably skip this gear and go to 3.73's for the V6 little monster. The $300+ that you are saving can go to the new ring and pinion and associated hardware. A set of 3.73's would be just what the doctor ordered for this car.

Dave

Ltngdrvr

3.73's would make the super low first gear in the 6 speed useless. You would be banging the rev limiter on a hard launch before you could get it shifted into 2nd.

Now if it had a 9000 rpm motor instead of a 7000 rpm motor then it would work.

Ltngdrvr

Maybe this will help: http://www.youtube.com/watch?v=ex3PF6Cs4dc&feature=fvw

Bert

Can we see some torque vs MPH curves to back that up?

Actually that's pretty much what I was originally thinking . . . once you get up into 2nd/3rd/4th and so on, if you want more torque/RPM's you're simply going to downshift; from what I remember about the final ratios, the 1st gear in the new 6 speed is still pretty low, even with the 2.73's.

I think you are basically choosing between a super-low first gear (3.31) at the expense of losing the versus high 6th overdrive; versus a real high 6th overdrive (2.73) with not so low first gear.

It would be cool to find a direct comparison real-world test on both MPG and 1/4 mile time, but I haven't found it yet.

corvettedreamin

OK, I get it. Lower GEAR ratio. . . but not a lower mathematical ratio.

Here's a link (even if it is GM):
Axle Ratios

I was never good at math anyway.

Time to get back to my Mars Lander navigation work . .

fritzOSU03

Here's a handy file I threw together to demonstrate the impact that wheels, tires, tranny gears and rear end gears have on the RPM to MPH comparison. I'd suggest that someone check my math considering I've never paid any attention to gearing and may have inversed some of the ratios but the numbers do seem like they work...

Edit: I don't think the file will work the way I've uploaded it. Anyone know how to get this into the forum?

Ltngdrvr

Huh???

I read that three times and still not sure what it says.

The low gear in the tranny doesn't change and neither does the top gear in the tranny whether you have 2.73 or 3.31 rear end gears.

The over-all ratios do change, the combination of ratios change, but the actual ratios in the tranny don't change.

Ltngdrvr

Super easy to use speed/rpm calculator right here: http://www.f-body.org/gears/

Covers all tranny ratios and rear end ratios and tire sizes, just plug the numbers in.

fritzOSU03

Sweet, I just used this to verify that my math was actually correct. Thanks for the link.

Bert

I guess I confused it by putting in the rear end ratios . . . I'm talking about the over-all effective net total drive ratios or whatever the right name is (I was tempted to say "final drive ratio" but I think that actually means the rear end alone, not the total combined)

With the 3.31 rear you effectively get a super-low first gear, with the 2.73 you effectively get a high 6th overdrive (final/net combined ratio -- internal gear ratio X rear-end ratio) . . . and yes it applies through all the gears, not just 1st and 6th, but I think you'll see it the most at the top and bottom extremes, in between you always have the choice to upshift or downshift.

Anyway I think I'm back to my original preference for the higher 6th versus the lower first

3Mach1

I believe I would go for the 3.31 gears if it were me. I have never heard too many complain that they have too much gear but lots of times people will complain about not having enough. Been there and done that. I am unsure of the mileage penalty but I bet its only 1 or 2 mpg. I would gladly give that up to be happy.

Its a rip off anyway to have to pay for a better gear. It costs them just as much to put in a 2.73 as it does the 3.31. I am all for Ford making money but....

I believe it would help you on resale also when the time comes but thats just me.

Ltngdrvr

I would also get the 3.31 gear for the V6 car, just as I would get the 3.73 for the V8 car.

The difference in fuel economy would not be enough to keep me from the better 1/4 mile acceleration and gratification!

3Mach1

This is my daily commute and I still think I would opt for the 3.31 gears. I am waiting to hear the real world gas mileage with both gear sets. I dont know whether to wait for the new Focus or get a V6 stang. The Focus should get close to 40 from what I hear. But, I have to spend so much time in the car I want something that I could enjoy. Thinking about possibly a stripper model with minimal options. One thing is for sure though and that is there wont be anymore GM cars or trucks in my driveway. Its Ford from here on out.

Ltngdrvr

Here are the rpm/mph/gear charts for 2.73 and 3.31 gears and 6 speed manual

RPM 1,2,3,4, 5, 6th Gear
500 4 6 9 12 15 22
600 4 7 11 15 18 26
700 5 8 13 17 21 30
800 6 9 14 19 24 34
900 6 11 16 22 27 39
1000 7 12 18 24 30 43
1100 8 13 20 27 33 47
1200 9 14 22 29 36 52
1300 9 15 24 32 39 56
1400 10 17 25 34 42 60
1500 11 18 27 36 45 65
1600 11 19 29 39 48 69
1700 12 20 31 41 51 73
1800 13 21 33 44 54 77
1900 14 23 34 46 57 82
2000 14 24 36 49 60 86
2100 15 25 38 51 63 90
2200 16 26 40 54 66 95
2300 16 27 42 56 69 99
2400 17 28 43 58 72 103
2500 18 30 45 61 75 108
2600 18 31 47 63 78 112
2700 19 32 49 66 81 116
2800 20 33 51 68 84 120
2900 21 34 52 71 87 125
3000 21 36 54 73 90 129
3100 22 37 56 75 93 133
3200 23 38 58 78 96 138
3300 23 39 60 80 99 142
3400 24 40 61 83 102 146
3500 25 42 63 85 105 151
3600 26 43 65 88 108 155
3700 26 44 67 90 111 159
3800 27 45 69 92 114 163
3900 28 46 71 95 117 168
4000 28 47 72 97 120 172
4100 29 49 74 100 123 176
4200 30 50 76 102 126 181
4300 31 51 78 105 129 185
4400 31 52 80 107 132 189
4500 32 53 81 109 135 194
4600 33 55 83 112 139 198
4700 33 56 85 114 142 202
4800 34 57 87 117 145 206
4900 35 58 89 119 148 211
5000 36 59 90 122 151 215
5100 36 61 92 124 154 219
5200 37 62 94 126 157 224
5300 38 63 96 129 160 228
5400 38 64 98 131 163 232
5500 39 65 99 134 166 237
5600 40 66 101 136 169 241
5700 41 68 103 139 172 245
5800 41 69 105 141 175 249
5900 42 70 107 143 178 254
6000 43 71 109 146 181 258
6100 43 72 110 148 184 262
6200 44 74 112 151 187 267
6300 45 75 114 153 190 271
6400 45 76 116 156 193 275
6500 46 77 118 158 196 280


RPM 1,2,3, 4, 5, 6th Gear
500 3 5 7 10 12 18
600 4 6 9 12 15 21
700 4 7 10 14 17 25
800 5 8 12 16 20 28
900 5 9 13 18 22 32
1000 6 10 15 20 25 35
1100 6 11 16 22 27 39
1200 7 12 18 24 30 43
1300 8 13 19 26 32 46
1400 8 14 21 28 35 50
1500 9 15 22 30 37 53
1600 9 16 24 32 40 57
1700 10 17 25 34 42 60
1800 11 18 27 36 45 64
1900 11 19 28 38 47 67
2000 12 20 30 40 50 71
2100 12 21 31 42 52 75
2200 13 22 33 44 55 78
2300 13 23 34 46 57 82
2400 14 23 36 48 60 85
2500 15 24 37 50 62 89
2600 15 25 39 52 65 92
2700 16 26 40 54 67 96
2800 16 27 42 56 70 99
2900 17 28 43 58 72 103
3000 18 29 45 60 75 106
3100 18 30 46 62 77 110
3200 19 31 48 64 79 114
3300 19 32 49 66 82 117
3400 20 33 51 68 84 121
3500 21 34 52 70 87 124
3600 21 35 54 72 89 128
3700 22 36 55 74 92 131
3800 22 37 57 76 94 135
3900 23 38 58 78 97 138
4000 23 39 60 80 99 142
4100 24 40 61 82 102 145
4200 25 41 63 84 104 149
4300 25 42 64 86 107 153
4400 26 43 66 88 109 156
4500 26 44 67 90 112 160
4600 27 45 69 92 114 163
4700 28 46 70 94 117 167
4800 28 47 72 96 119 170
4900 29 48 73 98 122 174
5000 29 49 75 100 124 177
5100 30 50 76 102 127 181
5200 30 51 78 104 129 184
5300 31 52 79 106 132 188
5400 32 53 81 108 134 192
5500 32 54 82 110 137 195
5600 33 55 84 112 139 199
5700 33 56 85 114 142 202
5800 34 57 87 116 144 206
5900 35 58 88 118 147 209
6000 35 59 89 120 149 213
6100 36 60 91 122 151 216
6200 36 61 92 124 154 220
6300 37 62 94 126 156 224
6400 38 63 95 128 159 227
6500 38 64 97 130 161 231

3Mach1

Thanks for posting this. I know I would want the 3.31s now for sure. My S10 with 3.42 gears runs 2100 at 70. This is with a 4.3 V6. Mind you it only has about a 5000 rpm at most to work with. More like 4800. It does make torque fairly quick max being at 2800.

3.31 gears might not be enough like someone suggested. I would not fear these gears one little bit. Just my 2 cents.

jeff s

If you do a lot of stop and go, in town driving, the 3.31s will be easier to live with and make the car feel much more peppy. You may even get better mileage than the 2.73's in this situation because you'll get up into high gear sooner and there should be less gear hunting.

The dollars per year you could theoretically save with the 2.73's on the highway won't add up to much. 2.73's worked in 70's landyachts behind torquey low rpm engines with 3 speed autos without OD. The 3.7 seems to be a fairly high-strung motor that may feel out of place turning 1600 rpm down the freeway. It will take a lot of downshifting or gearholding to take advantage of its power with the 2.73.

The only reason Ford is using these gears is to get the highway mileage ratings up. The V8 with obviously more torque gets a 3.15 gear with the same trans ratios if I'm not mistaken.

Don't fear the gear!

David Young

That's what i'm thinking. With the 3.31 gear ratio you might lose a couple highway miles per gallon but i think you might gain around one mile per gallon in city driving.

Ltngdrvr

Just looked at something else on these V6 cars that Ford has done. The tire sizes for the standard 17" wheels are really tall, taller than anything offered on V8 cars. The standard tires with the automatic are 28" tall, the tires that come with the manual tranny are 27.6" tall.

That is another way Ford is getting their high MPG numbers on the automatic cars.

This will also be something to consider for people who are planning on aftermarket wheels and tires or those who get one of the option packages with the 18" wheels or track pack with 19" wheel because those will have shorter tires and will change all the rpm numbers.