Gearing question for auto cars... 60ft and 1/4 mile thoughts

Recently, Rebecca Starkey set the TVS Coyote quarter mile record with a 8.58 at 157mph. Very impressive numbers for sure. Rebecca's car has a Turbo 400 transmission and 4.10 rear gears YES, 4.10 REAR GEARS! I know the TH400 has custom gearing for racing. I have a 3.55 geared auto 2015. I know a lot of guys like 3.15 or 3.31 gears in their auto and manual Mustangs. My first race/street car was a 86 GT.. Yes, I am 43 years young;) I ran 4.30 gears with a C4 with great success. i started with 3.55 gears and needed the car to 60 foot better. It was a nitrous footbrake car with a 3500 stall. I left on the bottle with both gears.. The car ran better with 4.30 gears with a dramatic improvement in the 60ft mark.. I know the new auto is aggressively geared in first letting the car run well with 3.15 or 3.55 rear gears.. It does not feel so aggressive that a 3.73 gear would hurt it in the quarter.. With the weight of the S550 the 3.73 would only help the car 60ft better... Right?? If any of you guys have tried the 3.73 in a blown auto car.. What was your thoughts and why you liked or disliked the 3.73 gear..
VMP's Rebecca Starkey Video

The TH400 is probably a 2 speed (uses 2nd as 1st) to prevent overpowering the tires and it probably has a state of the art torque converter.
The redline is probably 9k
The tires are probably taller than 28"
ET for really quick cars is all in the first 100-330 ft

So it seems right to me.

I put 3.31's in my Street driven Whipped GT automatic conversion from a Performance Pack and it feels perfect for my power level

I'm also using a Circle D converter btw

Aekrot1 said:

The TH400 is probably a 2 speed (uses 2nd as 1st) to prevent overpowering the tires and it probably has a state of the art torque converter.
The redline is probably 9k
The tires are probably taller than 28"
ET for really quick cars is all in the first 100-330 ft

So it seems right to me.

I put 3.31's in my Street driven Whipped GT automatic conversion from a Performance Pack and it feels perfect for my power level

I'm also using a Circle D converter btw

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I think I heard it shift from second to third. It would be no need to have a 3 speed transmission and make it a 2 speed.. They would just run a built powerglide.. A good ET for the REALLY QUICK CAR has the ability to Use the entire 1320.. If you have two cars that cross the finish line at 147mph leaving at the same time. The car A has a 1.28 60ft.... Car B has a 1.63 60ft... Car A will be the first to finish.. A good 60ft is just as important as the 100 to 330..

Dntalman said:

I think I heard it shift from second to third. It would be no need to have a 3 speed transmission and make it a 2 speed.. They would just run a built powerglide.. A good ET for the REALLY QUICK CAR has the ability to Use the entire 1320.. If you have two cars that cross the finish line at 147mph leaving at the same time. The car A has a 1.28 60ft.... Car B has a 1.63 60ft... Car A will be the first to finish.. A good 60ft is just as important as the 100 to 330..

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Some people go turboglide... The turbo 400 can be built a little beefier then the power glide in the 2500hp up range. More room for bigger gearing etc.

Im not sure if a glide or the 400 is better for the 15 up cars, they are pretty heavy so I think the 400 might be better. My 14 I went glide as it's easy to really get the weight down.

we have run as much as 4.10s, thats alot of gear though, but if your tuner can tune the car, you can do well with a gear and no converter, that was a centri though

pd shouldn't need as much gear, a converter will help as well

We just did a auto swap in my buddy kcc0521 car,he is keeping his 373's in for now to see how it runs.The car will be running a paxton sc and he has a drag wheel.setup.Probably be a couple more weeks as we just finished up the auto swap and all the computer coding,putting the paxton next then tune then track lol.We will post how it does.

I have 3.55 gears in my car with an auto. My car has a 20" drag radial that measures almost 29". I'm hoping that it won't be too much gear for my combination. My car has full BMR drag suspension, Circle D converter & Whipple supercharger that should make around 15lbs the way it is pullied. Really trying to make my car work on the 20" radial...

BDMACH1 said:

I have 3.55 gears in my car with an auto. My car has a 20" drag radial that measures almost 29". I'm hoping that it won't be too much gear for my combination. My car has full BMR drag suspension, Circle D converter & Whipple supercharger that should make around 15lbs the way it is pullied. Really trying to make my car work on the 20" radial...

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You'll be fine with the 29" tire for sure.

There is absolutely no reason to stick a steep gear behind the 6R80. Especially if you're F/I.

2015 Silver GT said:

There is absolutely no reason to stick a steep gear behind the 6R80. Especially if you're F/I.

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Wrong!!!.If u dont have a convertor and are fi,using higher gears will help the car get moving.Its simple math.

Tommy V said:

Wrong!!!.If u dont have a convertor and are fi,using higher gears will help the car get moving.Its simple math.

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You can do all the math you want but I'm talking from personal experience. They really don't work in these cars. Just look at the 1/4 mile list.;)

And u had an fi auto that u did gear changes too???.Your talking about a 4k pound car and without a convertor the only way to improve the 60ft is to change gears.The fast list has nothing to do with this statement unless u can show me a fi auto that loss et from doing a gear swap and did not have a convertor.Your one time experience is not alot of data when alot of other factors play a part in et.

http://www.mustang6g.com/forums/showthread.php?t=16739

Just look at this list and you'll see how futile your arguing is. The top 21 have 3.55's or less and most are 3.15's and 3.31's.

2015 Silver GT said:

http://www.mustang6g.com/forums/showthread.php?t=16739

futile your arguing is. The top 21 have 3.55's or less and most are 3.15's and 3.31's.

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What the hell difference does that make lol.I go to the track ALOT!!!.And just to make a point i see autos since your test was na,with full bolt ons 315 gears and tires and cant get a 1.6 60 ft.U can argue all day but if your an auto without a convertor,and running 331 gears your 60ft will be as good as if u had higher gears,ask any of the real track guys here.Sure the list has fast cars but i bet u money the fastesr autos have a convertor..Also sorry i think i m ight have accidentally earased some of your post.

2015 Silver GT said:

http://www.mustang6g.com/forums/showthread.php?t=16739

Just look at this list and you'll see how futile your arguing is. The top 21 have 3.55's or less and most are 3.15's and 3.31's.

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That is because that is what the cars come with stock. I don't think there are enough people running taller gears to know if it is better or worse.