I wanna get 4.10 for my automatic 2wd crewcab. Will it kill or help the mileage?

 

your milage will go down

 

Do you have 4.10's in your truck?

 

It doesn't matter what Usedtodrivechev (by the way, love the name) has or had in his truck.

The bottom line is that if you go up in gear size, you're going to lose mileage - there's no other way around that one.

It's like asking if you have a 2WD if the 4WD is going to get worse mileage. Of course it is!! The 4.1's are more powerful, therefore, you need and use more gas. More gas = less mileage.

 

I have a 96 Cobra and I went from 3.27 to 4.56. If I floor it it pulls like a monster and sucks gas but when I just cruise I've actaully gotten better gas mileage than the stock 3.27. So are you saying that bigger gear equals more gas no matter what tranny or engine? I know I have saved gas in my Cobra by switching to 4.56 but thats because I control the shift points w/ manual tranny. So I don't believe that a gear size will always kill mileage. Maybe too steep of a gear will kill mileage. I'm sure I will lose mileage but I'm asking the guys who have the gear so I know what to expect.

 

Well, I have no experience with a mustang, but I will tell you that you will have a hp gain like a madman with 4.1's over 3.55's but your mileage will also go down (and moreso if you have an automatic tranny). It's not like you'll be getting 9 mpg where before you got 15, but if you get 15 now, expect to get 12 or so.

I definitely believe you when you say that your mileage held, if not increased, in highway mileage because that's when those gears don't have to generate a lot of torque to get you going. 150's usually aren't like that because a 150 weighs a heck of a lot more than a mustang and is much less streamlined. Even at 80mph, you're going to be using the gears much more than you did in your mustang.

Only reason I say that you're almost guaranteed mileage reduction is because I know a buddy who HAD 3.55's and upgraded to gears on his 99 F150. Problem is - I don't know what gears he installed. But he said that he saw a 3mpg decrease....he said he didn't mind because he was getting the performance he wanted, but I know they were either in the upper 3's or lower 4's.

 

I have a 98 F-150 v-6 2wd supercab, running 4.10 gears and 34 in tires and in town I'm getting 14.0 mpg and on the highway right at 18.0 mpg.

 

On my 2000 5.4 F-150 I swapped out the factory 3.55s for 4.10s using the same height factory tires. The highway mileage dropped slightly, the city mileage stayed the same and the performance/towing improvement was fantastic.

 

Sounds good. Thanks for all th input. 4.10 it is. Actually I think mine is a supercab. Three door, right?

 

That would be the SCab alright.

A 3-door SCab means that you either have a 97 or 98.

 

Just out of curiosity - do you have stock tires on your truck or did you do some aftermarkets? I'm thinking of beefing up my gears because I'm going about 20 percent bigger than stock, and worry that my low end is going to suffer if I don't get some bigger gears.

 

I have 285/75/16. One guy in another forum said that his mileage gained about 30-40 miles per fill.

 

IT WILL KILL IT NO DOUBT ABOUT IT! BUT THE ACCELERATION U GAIN IS WORTH THE EXTRA DOLLAR. I TOOK OUT MY CATALATYC CONV. THAT REALLY KILLED MY GAS MI. BUT IT'S JUST PART OF MANY UPGRADES I HAVE.

 

Are you talking about a V6 or V8? I've posted this question in other V6 forums and 90% said 4.10 good choice because thay have that gear and the other 10% said bad choice but they don't have the gear. Here is a really good explanation from another site.

ok most peoples knowlege on gears are on cars... 3000lb cars... when you put lower gear the engine rpms go up alot... most cars have small tires... which make the gears act like they are even lower... its all about the weight of the car, gearing in the tranny, gearing in the axle and tire size...

take a 2000 3.8 mustang with stock tires
take a 2000 4.2 F150 with stock tires

replace both gears with 4.10's

well 4.10's in a mustang is goin to be extreme.... 4.10's in the truck it isnt...

mustangs come with anywhere of 2.73:1-3.47:1 gears... with small freakin tires... and they weight next to nothing...

F150's come with 3.08:1-3.55:1 gears with larger tires and like 2,000-3,000 more pounds than the mustangs...

anytime you improve the effiency over a vehicle you will get better mileage... in order to get the right gearing you have to match it up with your tire size, weight, and tranny gearing...

just as if someone did a cam and head job on their engine. it improves the effiency and as long as your not on it you will get better mileage... with gears as long as your not on it you will get better mileage...

i dont even know if any of that made since...

 

ok i agree on the weight and size of both vehicles... yes i have 410, posi track and a whole bunch of other upgrades, to include 75 shot of nos. My truck is a 4.2, and these gears will make it eat more gas, and you have to get different speedometer gear that you install at transmission. i got a 24 if i best remember, but i also have 20'' wheels. I can tell you alot about the things I'ved notice after different performance parts. just holla