If you have an auto, changing to 4,10 would mean a 27% increase in rpm at 5:th gear and 27% less top speed. I would expect a little less than a 27% increase in mpg tho. Maybe 15%?

 

I just called my local Ford service department. The guy said $70 to recalibrate my speedometer after I have the 4.10s installed.

 

What are you saying 426h? That a switch to 4.10 gears would cost you 27% of your top speed on the Stang? Meaning mine should top out at about 105 now instead of 145? That makes no sense to me...Then you say you would expect a 20+% INCREASE in mpg...I'm confused here...none of that makes any sense to me....clarify please...

 

gas mileage will go down with 4.10 gears, the engine will have to rev higher to maintain speed on the highway. top speed down, gas mileage down, and quarter mile time increased. Some people like the faster acceleration. I am quite happy as it is at the moment.

 

Yeah, please forget what I wrote above! The difference between a 4,11:1 and a 3,31:1 is about 20%. This means that your rpm increase 20% when you are at the same gear & travelling at the same speed OR that you lose 20% speed at equal gear & rpm. BUT, since the fifth gear is an overdrive (even with 4,11) you will not loose top speed.
Fuel consumption will probably increase at highway driving (when you are at 5:th gear), in the city it is probably about the same.

 

Has it been confirmed that the top speed is 145? I know that the speedo tops out at 145, but is that actually what the car is limited to?

 

I think the computer limiter is set to 143.

 

I know it will hit 140 with no problem....heehee....Probably do more like 160+ if the limiter wasn't there from the factory...feels like it has a lot left....

 

I agree she will do 140 with no problem and still feels real strong, like she wants you to go some more.

 

Where did you find that out? Or did you track test it? (that would be so sweeet!)

 

I thought I had read 149 somewhere?

I'll give it a shot though, I got the perfect place for it!

Oh wait a minute I don't have my car quite yet :bang:

 

I've got 4.56s in my 01. You'll accerlerate faster, but your speed in each gear will be different, however, if you go to a numerically higer gear, you're overall top speed will increase as your overdrive becomes usable. Here's an example from my 01 (the number reflects speed at redline):

The car can't pull the car in 5th gear much over 130 with the stock gears, but I have had the car over 140 at the track in 5th with the 4.56s and she was still pulling hard.

As far as the warranty, well, even if they say you will keep it, they can still find a way to void your warranty. I'd try to find a good reputable shop to install them (and only go with FRPP gears!). It shouldn't cost more than $300 in labor. I had mine done in AZ for $200 labor

 

4.56 !!

Whoooooo that's some wicked low gearing!!
Never thought about it like that about the overdrive but it makes sense.