Curious to actually see the difference between the 3.55's and 3.73 gears

[Driver72]

so is there 2 guys in the LA area with new 2011 GT's (one with 3.55 gears and one with 3.73 gears) willing to meet up and do a couple impromtu rolling runs (on a private road of course ) and have it video taped (one driver, one passenger in each car).

I'd like to do 40 mph rolls starting in 2nd gear and going to top of 4th (about 110 or so) to see if the 3.73's pull the 3.55 and by how much.
Also a 20 mph start in 1st and go to the top of 3rd would be interesting to see too.

PM me if you are interested, I'll do the video taping and will pay for some gas money.
I haven't decided whether to order the 3.55's or 3.73's and would like first hand account of the acceleration difference between the two.

 

[2013Boss302]

i should get mine on june 17th im down to participate i ordered the 3:73 gears. im in redondo beach

 

[Driver72]

Sweet. But you probably would want to do some break in first.

But just in case, hopefully we can find someone with 3.55's to get involved as well.
It should be fun and get some good comparisons.

 

[nocobrafornow]

i think it would be hard to tell that way, what if the guy driving the car with 3'55's can drive a lot better and wins. i think going to the track and use the same tire probably a dr for consistency and an independent good driver same day same track. thats just my opinion. good luck.

 

[Bob Cosby]

The difference would be minimal, and not enough to cover up any differences in driver input (as stated above). Even on a drag strip, if you could make everything else equal, you *might* see a difference of half a tenth to perhaps a tenth or so - assuming good traction for both.

 

[ringo01]

I will have to disagree. I think there will be a noticeable difference. On my 07 GT I had 3.55 gears and my buddy had an 08 with 3.31s.... Our cars had the same power mods, but I had 18 in wheels and he had 17s. My car was definitely faster, and I mean by a car length or two from a 40 to 110 roll. It could be argued I'm the better driver, but even when driving his car I can tell my car is for sure faster.

That's why I ordered 3.73s on my 5.0

I am interested to see the results.

.

 

[Driver72]

I've already thought of the "driver" mod.
That's why, if they'd be ok with it, I'd have them switch drivers and do a roll or to that way too.

I'm an experienced drag racer myself, and I know that there is MUCH more driver input that can affect results at a drag strip then from a rolling run. Rolling runs show much better the ability of the car and a lot less the ability of the driver.
If you really want, which I should probably do, to show how the gears affect acceleration, start at 20 mph in 3rd gear, so the rpms are really low, then get on the gas at the same time and see how each car pulls in 3rd and into 4th.

We could also just hook up my VBox to each car and time the 20-100 mph time or any other desired speed. And also check the distance covered to get to that time.
That will give me how much quicker the 3.73's accelerate and in how less of a distance.

Again the reasons I ask is, I believe the 3.55's will be the superior gear choice for drag racing, but wondering how much I'd be giving up in rolling runs vs 3.73 geared cars.

 

[Ray Lucca]

Would also like to know how many RPM's at say 60, 70, 75, and 80 in 6th gear for each rear axle ratio...How is the new 5.0 exhaust, loud enough, any drone???

 

[Driver72]

Would also like to know how many RPM's at say 60, 70, 75, and 80 in 6th gear for each rear axle ratio...How is the new 5.0 exhaust, loud enough, any drone???

There is a total of about 300 rpm difference between the three ratios.
At 70 mph
3.31 is around 1850 or so rpms (give or take a few)
3.55 is around 2025
3.73 is around 2150

 

[Conechaser]

I think us autoX and track guys would be more interested in what is the max MPH in each gear between the three gear ratios.

 

[Driver72]

Technically the redline of the new 5.0 is 6850 rpms.
Fuel cutoff is 7000 rpms.

So I'll give you the top speed in each gear at the 6850 rpm redline for 3.55's and 3.73's
If you take it the extra 150 rpms you'll get another 1-4 mph out of each gear (about 1 mph in 1st and around 4 in 5th).

3.55

1st - 42.4 mph
2nd - 63.8
3rd - 91.8
4th - 117.5
5th - 155.1
6th - 155 limiter


3.73's

1st - 40.0
2nd - 60.3
3rd - 86.7
4th - 111.1
5th - 146.6
6th - 155 limiter


Now do you guys see why I've said I think the 3.55's are the best gear for 1/4 mile racing, especially if you add 30-40 hp to the car?
With the 3.73's you finish the 1/4 mile right at the top of 4th as you bang into the fuel cutoff around 113 mph (which would give you a trap speed in the 111.5-112 mph range). If you have an especially strong running car and you'll need to shift to 5th to finish, and that will end up costing you time and trap speed.
Add 10-40 hp and the same story applies.

With the 3.55's you get 117 mph at 6850 and close to 119 at fuel cutoff.
That allows you stock to run the 1/4 in 4th with no problems and you should cross the line somewhere in the 6600 rpm range...right in the peak of the power range.

Further, add up to 30-40 hp and you could still get to the stripe at the top of 4th with a traps in the 116-118 mph range.

Also notice with the 3.55's you get to the 155 mph in 5th gear.
In the 3.73's you need the shift to 6th.

The reasons above are why I will most likely order my 11 GT with the 3.55's
I think they'll produce slightly better 1/4 mile times stock over the 3.73's and probably up to .2 and 1-2 mph faster than the 3.73's on a car with up to 40 hp in mods. (and could possibly still be faster with more power in mods, as 3.73 gears will offer less traction at launch and between shifts as power rises, costing time and speed).

For auto-x and track junkies, the 3.73's will probably be the best choice.

You can also see why Ford has the 3.55 gears as standard everywhere else in the world but the U.S.
As they measure 0-100 kph (62.1 mph). With the 3.55's this is achieved right at the top of 2nd gear.
The 3.31 gears offered as standard here was simply to improve the ever stricter EPA fuel economy regulations.

 

[Conechaser]

Thanks for the info!!

Just for giggles, do you have the numbers for the 3.31?

 

[Driver72]

I'd have to run them but off the top of my head it's about

1st - 44
2nd - 65
3rd - 95
4th - 123
5th - limiter
6th - limiter