Gears effect top speed?

[MustangMuscleV8]

ok this is a question that has been on my mind for the last 2 weeks lol so do gears help acceleration with sacrifice to top end, I know it doesn't matter about top speed because of 1/4th mile and all, I was just wondering!


Hope you can help!

 

[Bone Racing]

yes....yes they do

 

[jadesville]

sure do

 

[mrvax]

No, they won't. Since your car cannot ever hit it's theoretical top speed due to wind resistance and HP, they will not effect your top speed.

Put it this way, if you have 3.27's and top out at 142mph, by installing 4.10s, you will still top out at 142 but you will get there quicker.

If it was possible for you to wind out 5th speed at 6000 rpms and hit 180, then yes, the gears would limit you.

Using the Corral gear calc, we see that with 3.27's in 5th gear at 6000rpms with a T45 tranny and 17" rims, your top speed is 209mph.

Same thing but 4.10s gives a top speed of 167mph. Neither of which you can ever hit.

 

[downsouthman1]

Very well said. I've actually heard instances though where when a person lowered their gears (ie: 3.27s to 4.10s) they were able to achieve a higher top speed to to more HP & TQ @ the old wind resistance barrier. I will soon find out after my clutch is broken in. See sig.

 

[blubullitt]

I have 3.73's my top speed is still 150 ive personally gone that fast after the gears. I was expecting to hit 140ish after hearing everyone say that gears limit your top speed.

 

[downsouthman1]

That's what I'm hoping is that I'll be able to break 138mph. I would've been able to do it that day as I was still accelerating but my wife was sitting next to me & flippin' out some. I'll test it by myself so I won't be curious later.

 

[MustangMuscleV8]

ok so some say they do and some say they don't...hmmm...

 

[downsouthman1]

Well I'm in a long line of people that has said your theoretical top speed decreases when you lower your gears (ie: 3.27s-4.10s). However your actual top speed increases unless you have more HP than anybody on these forums.

 

[MustangMuscleV8]

alright let me ask it to you this way: 2 stock mustangs 2000 GT 5 speed manual transmission (the same) you take and you change the gearing from stock --- to 4.10's how is the top speed different from stock?

 

[blubullitt]

I dont know about gear calculators and such. All I know is personally after gears my top speed didnt change at all. I pegged the spedometer actually I might have been going a tad over 150. But the car feels much better with the gears. I can be on freeway in 5th and accelerate without downshifting. On stock gears 5th gear almost feels like overdrive. It was my favorite mod by far and I have a couple things done to my car.

 

[MustangMuscleV8]

sweet! But don't you have to change something about the speedo to be correct? (or the milage meter)

 

[downsouthman1]

Yes your speedo will be altered. But to answer your earlier analogy of the 2 stock similar Mustangs. When you lower the gears in 1 it will have a lower theoretical top speed. But because you are @ a higher RPM @ any given speed you have more HP & TQ availiable to you. That's what causes a higher actual top speed.

 

[blubullitt]

sweet! But don't you have to change something about the speedo to be correct? (or the milage meter)

Yes you can get a speedcal its like 140 dollars or so, or you can correct it through a chip. I did a few mods at once and just got a dyno tuned chip that was tuned to all my mods.

 

[MustangMuscleV8]

So your saying, because you have the gears, you actually have more HP and Torque to get you to that higher speed so it doesn't change?

 

[billyfe390]

A stock mustang in fifth gear doesnt have enough power to do much of anything but if you change the gear ratio to 4.10 your top end will increase only because you can use fifth.

The part that most people dont understand is that in the real world a car with stock 3.27 or 2.73 gears trying to go as fast as possible will not be able to use fifth gear effectively making it a four speed car. Now in that same car you put 4.10 or 3.73 gears in it and do the same thing you will be able to use fifth gear therefore increasing your top speed.


Check out this past discussion same topic http://forums.stangnet.com/showthread.php?t=405436&page=1&pp=25

 

[rx7speed]

Yes your speedo will be altered. But to answer your earlier analogy of the 2 stock similar Mustangs. When you lower the gears in 1 it will have a lower theoretical top speed. But because you are @ a higher RPM @ any given speed you have more HP & TQ availiable to you. That's what causes a higher actual top speed.

actually a big reason why they work better after gears is more torque due to torque multiplication

a motor putting out 200lbs/ft of torque through a total gearing of 5:1
vs
same 200lb/ft motor of torque through total gearing of 2:1
motor one puts out 1000lbs/ft at the wheels
motor two only puts out 400lb/ft
at least through an ideal world with no drivetrain loss

but hp stays the same at the wheels as with the motor again not taking into account drivetrain loss


so yes gears can affect TRUE top speed and raise it a little

but theoretical (what speed you can reach if there was no drag) top speed is going to go down

 

[Jackie Chan]

Oh No not this ****ing bull **** again

 

[MustangMuscleV8]

oh ok I see what your saying...

thanks!