3.73 to 3.55 would it be worth it? How much will it hurt if at all?

[Godzirra]

Logic in this is. I'm not losing anything from stock gearing on the street. On stock tire 255/40/19(~27 inch) with 3.73 in 4th (1.32) I could go 114 at redline...On current tire 335/30/18(~26 inches) with a 3.55 in 4th (1.32) I can go 115(with current 3.73 in car I can only go 109mph in 4th) so not much difference at all. On my current race tire which is 26 inches with 3.73 i'm limited to 109mph and have to shift to 5th to go through quarter. By changing to the 3.55 alone I can go 114 still making me shift to 5th. But if I change to a 28 inch tire for the strip, with a 3.55 gear it would allow me to go 124mph in 4th effectively eliminating the shift to 5th which should counter what little I lose in acceleration in low end of track by going to higher gear and bigger tire if I lose any which I'm sure I will, just how much is the question?

Thoughts and opinions please? Would I lose more on the low end of the track than I would gain on top end by eliminating the extra shift?

Car is 2012 Manual GT on 150 shot.

 

[Godzirra]

bump?

 

[konablue11gt]

not sure of the answer but want to see what others think as well

 

[skwerl]

What's your 60' and 330' times? What are you currently running in the quarter and where are you losing time? Not enough info to give you any meaningful advise.

 

[DTony]

There's only one way to find out. It seems like these 5.0's like less gear, especially with a power adder. I am getting ready to take my 3.73's out and go to 3.31's.

 

[Godzirra]

What's your 60' and 330' times? What are you currently running in the quarter and where are you losing time? Not enough info to give you any meaningful advise.

I sixtied 1.65 and ran a 11.6@118 on a fried diff and bad slipping clutch. Im spinning out of hole on et streets as is. Car isn't trapping and I'm baby shifting to 5th right after 1000ft mark. I think takin out gear and going bigger tire will help traction on low end. And not shifting to 5th on top end will save me there. IMO I think it's a win win but I was just lookin for opinions or if I'm missing something here and feedback from others who've done this.

 

[Morris]

In for the opinions, as I have been wondering the same thing. The 3.73 seems like too much for the street and I spin like crazy at the track, my 2012 has no power adders other than a cat back. I want to buy a drag set up for the rear and was torn between the tire size, gears, shifting to fifth issue etc. I needed to see a gear calculation, but that's only part of the story.:..........so I'm looking forward to this thread.

 

[Godzirra]

I've done most of the calculations between gear and tire size in original post

 

[Morris]

Can you link the calculator that you used? I'm going to run a 27" tire same as stock but a 295/35/19 for my street tires and I want to see where that would put me. I don't have the power adders yet so I'm not gonna trap as high as you would. Down the road when I add some power the 3.55 with a 28" tire seems like the ticket. For now though I may not have enough juice to pull that off. Last time out I only trapped at 109 with a shift just before the line. Maybe at my power level I could cross the line in 4th with the 3.73's and a 28" tire? Also that 3.55 with a 27" tire might be good enough for me to cross the line in 4th then when I add power and trap speed buy the slicks with a 28" for race days and I should be good to go.

I'm sort of kicking myself now for ordering the car in the 3.73's. It's too much gear for the street and not enough for the track (at my power level) to run a big drag tire.
What I would really like is to find that sweet spot where I could run the 27" for now and trap in 4th, then bump to the 28" later when I add power and retain the same gear.

 

[Godzirra]

Can you link the calculator that you used? I'm going to run a 27" tire same as stock but a 295/35/19 for my street tires and I want to see where that would put me. I don't have the power adders yet so I'm not gonna trap as high as you would. Down the road when I add some power the 3.55 with a 28" tire seems like the ticket. For now though I may not have enough juice to pull that off. Last time out I only trapped at 109 with a shift just before the line. Maybe at my power level I could cross the line in 4th with the 3.73's and a 28" tire? Also that 3.55 with a 27" tire might be good enough for me to cross the line in 4th then when I add power and trap speed buy the slicks with a 28" for race days and I should be good to go.

I'm sort of kicking myself now for ordering the car in the 3.73's. It's too much gear for the street and not enough for the track (at my power level) to run a big drag tire.
What I would really like is to find that sweet spot where I could run the 27" for now and trap in 4th, then bump to the 28" later when I add power and retain the same gear.

http://www.kabamus.com/garage/gears.html

 

[Morris]

Thanks!

 

[psfracer]

OP, how soon are you squeezing out of the hole with the 150 shot and your current tire?

 

[UltraKla$$ic]

There's only one way to find out. It seems like these 5.0's like less gear, especially with a power adder. I am getting ready to take my 3.73's out and go to 3.31's.

I agree! The car I test drove before buying had 3.31's and the car I bought has 3.73's and I liked the 3.31's better!!!! I like the way 1st stretches waaaaaay out with the 3.31's.

 

[Morris]

What's our transmission gear ratio?

 

[UltraKla$$ic]

Gear ratios
First 3.66
Second 2.43
Third 1.69
Fourth 1.32
Fifth 1.00
Sixth 0.65
Final drive 3.31:1

 

[Godzirra]

OP, how soon are you squeezing out of the hole with the 150 shot and your current tire?

At 3k wot 75 shot kicks on ramping to full 150 in .6 seconds. I've tried lengthening ramp time for more traction and lowering initial kick to 50 as well. On 26x11.5x17 et streets on 14psi. Our track is a little more lack luster on prep than others but usually only average mid to high 1.6s in sixty

 

[psfracer]

Ok, I would go to a 28 tall tire, leave the gears alone, and go with the 100 right out of the hole (above 3,000) and ramp it all in as fast as the tire will allow.

 

[Godzirra]

Without changing the gear though I'll still be making a slow shift to 5th after thousand foot mark. Im replacing the diff here soon and figured id do the change anyway just to see while I'm in there. I can always swap back gears if needed

 

[ford20]

Just curious, what do you shift at or do you have an auto?

 

[Morris]

I think I'm gonna do the 3.55's.

That way with my street tires I would be at 120 mph at 7k in 4th and 111 @ 6500

Then if I use a drag tire like a 275/60/15 to bump up to 28" OD I would be looking at
124 at 7k.