BlackSS/SC

So I'm getting transmission work done and changing the final drive gear ratio.

So I'm torn between what gears to get. Stock is 4.05 and at the end of the 1/4 mile as is I'm at 113-114mph styaing in 3rd gear.

My other options are 3.82 or 4.45.

I'm leaning towards the 4.45 gears but I will have to shift into 4th gear in the 1/4 mile then. The 3.82 gears will let me stay in 3rd gear and since I'm turbo put more load on the engine to get the turbo spooling quicker.

This is all 1/4 mile stuff with 26" OD slicks. I don't care how it is on the road.

originaladrian

how much time u think the 4th shift will add on?

BlackSS/SC

Not sure. Right now I can just stay in 3rd and I'm around 7000-7200rpm trapping.

ralliartist

Hardcore drag racers don't drop down a gear. They get a bigger gear. If you intend to drag race, you should go with the bigger gear. You know what mine and john's opinions are.

And here is your new gear ratios with the 4.45 final drive

RPM 1st Gear 2nd Gear 3rd Gear 4th Gear 5th Gear
500 3 5 7 10 12
600 3 6 9 12 15
700 4 7 10 14 17
800 4 8 12 16 20
900 5 9 13 18 22
1000 5 10 15 20 24
1100 6 11 16 21 27
1200 6 12 18 23 29
1300 7 13 19 25 32
1400 7 14 21 27 34
1500 8 15 22 29 37
1600 8 16 24 31 39
1700 9 17 25 33 42
1800 9 18 27 35 44
1900 10 19 28 37 47
2000 10 20 29 39 49
2100 11 21 31 41 51
2200 11 22 32 43 54
2300 12 23 34 45 56
2400 12 24 35 47 59
2500 13 25 37 49 61
2600 13 26 38 51 64
2700 14 27 40 53 66
2800 14 28 41 55 69
2900 15 29 43 57 71
3000 15 30 44 59 73
3100 16 31 46 61 76
3200 16 32 47 62 78
3300 17 33 49 64 81
3400 17 34 50 66 83
3500 18 35 52 68 86
3600 19 36 53 70 88
3700 19 37 55 72 91
3800 20 38 56 74 93
3900 20 39 57 76 95
4000 21 40 59 78 98
4100 21 40 60 80 100
4200 22 41 62 82 103
4300 22 42 63 84 105
4400 23 43 65 86 108
4500 23 44 66 88 110
4600 24 45 68 90 113
4700 24 46 69 92 115
4800 25 47 71 94 118
4900 25 48 72 96 120
5000 26 49 74 98 122
5100 26 50 75 100 125
5200 27 51 77 102 127
5300 27 52 78 104 130
5400 28 53 80 105 132
5500 28 54 81 107 135
5600 29 55 82 109 137
5700 29 56 84 111 140
5800 30 57 85 113 142
5900 30 58 87 115 144
6000 31 59 88 117 147
6100 31 60 90 119 149
6200 32 61 91 121 152
6300 32 62 93 123 154
6400 33 63 94 125 157
6500 33 64 96 127 159
6600 34 65 97 129 162
6700 34 66 99 131 164
6800 35 67 100 133 166
6900 35 68 102 135 169
7000 36 69 103 137 171
7100 37 70 105 139 174
7200 37 71 106 141 176



stock gearing, 4.05 final drive

RPM 1st Gear 2nd Gear 3rd Gear 4th Gear 5th Gear
500 3 5 8 11 13
600 3 7 10 13 16
700 4 8 11 15 19
800 5 9 13 17 22
900 5 10 15 19 24
1000 6 11 16 21 27
1100 6 12 18 24 30
1200 7 13 19 26 32
1300 7 14 21 28 35
1400 8 15 23 30 38
1500 8 16 24 32 40
1600 9 17 26 34 43
1700 10 18 28 36 46
1800 10 20 29 39 48
1900 11 21 31 41 51
2000 11 22 32 43 54
2100 12 23 34 45 56
2200 12 24 36 47 59
2300 13 25 37 49 62
2400 14 26 39 52 65
2500 14 27 40 54 67
2600 15 28 42 56 70
2700 15 29 44 58 73
2800 16 30 45 60 75
2900 16 31 47 62 78
3000 17 33 49 64 81
3100 18 34 50 67 83
3200 18 35 52 69 86
3300 19 36 53 71 89
3400 19 37 55 73 91
3500 20 38 57 75 94
3600 20 39 58 77 97
3700 21 40 60 79 100
3800 21 41 62 82 102
3900 22 42 63 84 105
4000 23 43 65 86 108
4100 23 44 66 88 110
4200 24 46 68 90 113
4300 24 47 70 92 116
4400 25 48 71 94 118
4500 25 49 73 97 121
4600 26 50 74 99 124
4700 27 51 76 101 126
4800 27 52 78 103 129
4900 28 53 79 105 132
5000 28 54 81 107 134
5100 29 55 83 109 137
5200 29 56 84 112 140
5300 30 58 86 114 143
5400 31 59 87 116 145
5500 31 60 89 118 148
5600 32 61 91 120 151
5700 32 62 92 122 153
5800 33 63 94 124 156
5900 33 64 95 127 159
6000 34 65 97 129 161
6100 34 66 99 131 164
6200 35 67 100 133 167
6300 36 68 102 135 169
6400 36 69 104 137 172
6500 37 71 105 139 175
6600 37 72 107 142 178
6700 38 73 108 144 180
6800 38 74 110 146 183
6900 39 75 112 148 186
7000 40 76 113 150 188
7100 40 77 115 152 191
7200 41 78 117 155 194


Obviously the lower the gear the slower the acceleration.

Z Speed

how would u get the different gear ratio? Curious as to what you found.... I know with the new turbo balts have a lower final drive

BlackSS/SC

LNF balt's are 3.82 gears. LSJ is 4.05 and the 4.45 ratio can be found in some Saturn and Saab F35s.

You have to change the main shaft because the pinion gear is there and the ring gear.

Z Speed

ahhh gotcha... I was soooo pissed when i had to replace my transmission and 3 weeks later the turbo cobalt tranny was available... I would of rather gotten the longer gear ratio for my car.

ralliartist

I'm having trouble understanding why everyone wants to the lower gear. Can someone explain that too me? All that gives you is better gas mileage. You guys do realize that if GM would have stuck with a 4.05 gear that the turbo ss would be a lot faster than it is right now right?

BlackSS/SC

Thanks for the info Ralli! You're da ****!

Keep the opinions coming in!

spike

where might one get diffrent final drive gears?

BlackSS/SC

You can get a trans for cheap out of a 99+ Saab 9-3 and take the main shaft & ring gear out of it. They were avalible in 3.82, 4.05 & 4.45. Otherwise you could order them from a dealer.

06blackg85ss

iTrader: (1)

I'd like the 3.82 ratio with the TQ of a turbo setup, it'll actually give you an almost usuable 4th gear

BlackSS/SC

4th gear? Do you mean 1st gear maybe?

cruisn

I would go with the 4.45 personally. if its only for drag racing whynot, first will be useable still since it turbo and there is a slight lag. but 2-3 will pull harder getting you a better time, also if your a quick shifter grabbing 4th doesnt hurt you. the jolt from dropping the clutch after grabbing 4th can sort of jolt your car ahead a little, thats waht I noticed in my 2.4 as I got my p.b grabbig 4th about 60 feet form the end of the track

06blackg85ss

iTrader: (1)

meant final drive//// instead of the 4.05

BlackSS/SC

I'm so torn up over what to choose lol.

The 3.82s sound nice because No 4th gear and better topend, also was thinking more load on the turbo at low rpm with the 3.82s.

4.45s would help a lot on the low end and it just seems right for drag racing.

qwikredline

Ralli may have confused folks, he is right on, but remember the lower the numerical ratio, the higher the gearing. Therefore 3.82 = tall or high gear; faster top speed, slower launch. and 4.45 short or lower gear, slower top speed, faster launch. Hammer down buddy! and remember we are drag racing here elapsed time is all that matters, top speed dont mean dick

Hey ralli, me and blackss are building a twin engine LNF Cobalt 600 hp with just a tune and awd. Evo's are running for cover, John Force is afraid ......

BlackSS/SC

Don't forget about the four wheel steering!


Keep the comments coming!

spike

can u just order the 3.82 final drive main shaft & ring gear from a dealer.....If so how much do u think it would cost? I would really like 2 have it for the old turbo swap...it would make the power get 2 the ground instead of just spinning tire

Killa SS

iTrader: (1)

would the 3.82 gearing improve gas milage as well? i wouldnt mind doing this as to improve first gear, lower rpms cruising in 5th and increase MPG

USMCFieldMP

iTrader: (1)

I'd go with the 4.45's... you can probably leave the line in 2nd gear then. 1st gear would be a waste.

But, on the other hand... the long gears will give you less shifting and more time in your powerband.

Deathscythe

Hey ralli, could you post the gearing for the 3.82 final drive? I wonder what the choice would be for those of us who are supercharged? I would like to get more use out of first gear if possible.

BlackSS/SC

You could order it for the 08+ LNF cobalt, not sure of the cost.
Yes, they would increase fuel economy as the revs on the higway would be lower.
That's why I'm not sure what to choose. Most likely will be the 4.45s. I may be leaving in 2nd gear because 1st will be even more useless.

I do see your point on beeing in the powerband longer and less shifting with the 3.82 gears though.

If I was SC I would choose the 4.45s for sure because of the wider powerband.

KillerBee

Very interesting good info guys.

Killa SS

iTrader: (1)

sweet. what would be the cost of this? the parts that is