Driver72

Depends on how important drag racing is to you?

From what I've seen so far, with the 3.73's you get to the 1/4 mile stripe right near redline in 4th.

That's great on a slightly slower track, but what if you are on a "fast" track or you add a mod that gives you 10 hp.
In those cases a shift to 5th may be necessary in the 1/4
And in needing that, it may not benefit you any over the 3.55's where you then may finish the 1/4 mile in the top of 4th instead of needing the shift to 5th.

If with the 3.73's you are not able to hit 115-116 mph in 4th, having the 3.55's may be the better choice, if with them you CAN hit 115-116 mph in 4th.

And as someone else has already said, the 3.55's may also be a bit easier to launch allowing a bit higher rpms during the launch and a bit less tire spin going into 2nd.
Keep in mind, the more power you have, the taller gearing you can get away with.

4.10's were probably great in the 315 hp 4.6 GT as that engine didn't make enough power and having lower gearing helps that car.
Can you imagine having 4.10's on a GT that had 550 hp? Spin city.


If 3.55's come standard in Canada, it might be worth just getting the car that way.

drew2000

Ok, so how about someone who's not going to drag the car, but more interested in back-road driving with some interstate thrown in. Would the 3.31's be too high? From what I read, the 5.0 is a rev-happy motor so the 3.55's might be best for all-around performance.

Gene K

Thats supposed to be impressive? CAI/Tune 2005's have been the same time on factory gears and tires.

3.73 hits the hard limiter (7000 rpm) at 111.5 mph which means either they shifted to 5th or were riding the limiter in 4th. Finish Line Speed is approximately 2 mph higher than trap speed.

Gene K

That depends on what gear you want to use. OD is taller in the new trans so the gears will act one size smaller (numerically) in OD. Direct (Now 5th instead of 4th) will be the same. 1st is 8.3% Lower. 2nd is 21.5% Lower. 3rd is 28% Lower. 4th is 32% Lower.

With 3.55 Gears you will seldom use 1st in normal driving on the street as launching in 2nd (2.43 x 3.55 = 8.63) will be like launching in 2nd with 4.30 (2.00 x 4.30 = 8.60) with the old trans.

Gene K

Speed in 4th (Keep in mind trap speeds are the average over the last 60' and you will need 1.5-2.0 mph extra to avoid the limiter at the finish line). These are for the hard limiter. You will start to lose power at 6850 rpm as the soft limiter cuts in.

3.73 = 111.5 mph at 7000 rpm (Hard Limiter)

3.55 = 117.1 mph at 7000 rpm (Hard Limiter)

3.31 = 125.7 mph at 7000 rpm (Hard Limiter)

WeinerDog

Does the 4.3 second 0-60 (with the 3.73's) that MT is claiming involve shifting to 3rd? Sorry, don't know all the ratios...

hawkeye18

1 = 3.66
2 = 2.43
3 = 1.69
4 = 1.32
5 = 1.00
6 = 0.65

These are the ratios. Given a final drive of 3.73, 255/40/19 tires (for the brembo package) and a top RPM of 7000 (with 6850RPM after the slash), top speeds in each gear would be:

1 = 41.23/40.05
2 = 62.11/60.34
3 = 89.30/86.75
4 = 114.33/111.06
5 = 150.92/146.61
6 = 232.18/225.55

Now obviously you're not gonna get to 232mph as you'd need a heluva lot more than 430hp to get there, but that should give you an overall idea of what you'd be dealing with. As you can see, you can get to 60 in second gear... but just barely. 0-60 dashes would be made easier though, as you just go 'til you wind second out, then you're at 60!

Hope this helps.

WeinerDog

Thanks for the info. I was going to be extremely impressed if that 4.3 included a 2-3 shift. So instead of extremely impressed I'll remain very impressed. :-)

Fugitive

It will be intersting to see if any mags do any runs with different gearing. Hope its sooner than later because i want to put my order in :P

hawkeye18

Alright, well whip some more numbers up then. These are top speeds in each gear assuming 255/40/19 tires, a 3.55 rear end, and a manual at 7000 rpm / 6850 rpm respectively.

1 = 43.33 / 42.40
2 = 65.26 / 63.86
3 = 93.83 / 91.82
4 = 120.13 / 117.56
5 = 158.57 / 155.17

And sixth doesn't matter, since you won't ever see it.

The 3.55 rear end is 5.07% taller than the 3.73, so all else being equal, performance stats will be lowered by 5% accordingly.

So, the 4.3s 0-60 should turn into a 4.51 second 0-60, that 12.8 in the quarter should turn into a 13.44... SHOULD. These are all numerical constants, and the real world will give little resemblance to these numbers. Things like fuel octane, shifting times, tire pressure, driver skill, etc. will mean these numbers get thrown out the window... but they are a good place to start for a baseline on the difference between the gearings.