Take 3.55 and divide it by 4.10

It's 86.5%, so that's a 13.5% reduction in speed for a given RPM.

 

Go with the 4.10's for sure....Bryan and I are LOVING ours to say the least. Car feels like it wants to pull the front end off the ground when ya drop the hammer in 1st and you'll be through the first 3 gears in what feels like a heartbeat. If you lose 15 mph on top end who cares! How often do you drive 150mph vs. how often you sprint to 60 or 70? To0 answer the speedo question, it does need to be tuned to fix the difference.. I had my wife pace me and my speedo reads 90 when i'm only doing 75. My SCT flash will fix it for me and give me the extra hp and shift points I'm looking for. Not too bad for 369.00+dyno time.....

 

In the summer months I have to travel the express way at about 78MPH 240 miles up and 240 miles back. My concern with 4:10 gears is the car going to be racing to much and is the mileage going to drop from what might be 21 MPG to 18 MPG. I enjoy the speed but since I will be making this trip I need a car that will be good on the highway trip too.

 

Mine's turning around 2600rpm at 75 with the 4.10's.....Can't be sure about mileage as I haven't had the time to put enough miles on it to tell the difference. If you're doing thousands and thousands of miles in the summer alone then perhaprs the 3.73 would be better for you specifically. I'd say the other 6-9 months a year you'd be happy you paid for the extra gas during the summer though as the performance from the 4.10 is amazing!!!!!

 

Is going to the 4:10's the same as if going 75MPH I go from overdrive (5th) to 4TH? As far as engine RPM's?

 

I doubt it would be that drastic......but it'll run 2600-2700 rpm at 75 or so....my auto is putting up thos e numbers anyway....i'd think it would be the same for everyone on the '05.....

 

Some were saying the new stang would not need the odo calibrated since it reads off the wheel not the tranny. Sounds like you proved that wrong.

 

VERY good point, and important. This particular point is usually missed in these forums.

 

The best way to equate what the 4.10 are like in the 05 stang is this -> If you have ever driven a new full size truck with a v8 on the hightway - it is almost the same in RPM's. For me it is alot like my 2000 Dodge Ram 1500 when I drove round trip 180 miles each day. I would not like 4.10's in my stang for that drive. If my plan was drive it that far - I would recommend stock gears of 3.73.

 

I don't know what the gear ratios are for the auto, but play with this. I've linked it in several threads, but it keeps coming up, and I think it's useful. You can figure out what RPMs you'll be ridin' at whatever speed, just plug in the numbers and change up the tire size and axle ratio to match what you've got or what you're planning to do, and viola....

MPH and gear calculator

gear ratios:

1st: 3.38
2nd: 2.0
3rd: 1.32
4th: 1.0
5th: .67

axle ratio: 3.55

tire size 255/50/17

 

With the 5spd the question I have is how many shifts 0-60 with the stock 3.55s versus 4.10s?

Does anyone have the shiftpoints in MPH for both or is there a way to calculate it?