I have a '97 F150 XLT. 5.4L with 3.55 gears. If I switch to 4.10's what kind of changes would I notice?
I also pull a 6500lb. Weekend Warrior quite often and was told this would help out.

Also what can I expect to pay to have this job done?

Thanks for any input

 

Do you have stock size tires? Drive unloaded on the highway often?
If you do then you might notice that your gas mileage drops a bit. But it might not.
Sometimes a bit lower gearing improves the mileage because the engine doesn't have to work as hard. I'm sure you'll see quite an improvement in the way it tows.
Is your truck a 4X2 or 4X4?
I'm not sure of the cost but hopefully someone will come along with an idea on that.

 

got my 4.10's from reider racing. best price ive found for precision gears. id get a reputable shop. youll like them. if you live an area with a lot of hills and mountains, youll be surprised with the mileage. it may go up. mine did.

 

Tires are not stock. 285-75-16 and truck is a 4x4
Along with the towing I do drive 40 miles to work each day on the freeway

 

if u have 285's then 4.10's are perfect.

 

A close friend of mine has a '99 4.6 extended cab 2wd and he swapped from 3.08's to 4.10's and had not real noticable gas milage change. Thought he was bs'ing at first to cover up a mistake (his e/t's barely improved at all) but sure enough after driving the truck a while, the milage is about the same as my 5.4 with 3.55 gears. If anything I'm jealous now b/c he can tow in Overdrive.

 

theyll give you a better 60 ft time but you need to do other things to make up some hp at the end. ive run into this with mustangs.

 

I have the stock setup with 265/75 r16's would 4.10's be too much?

 

fordman311 your actual ratio will be a little lower than AgentOrange with the 285/75/16. The combo. of 410's and 285/75/16, which will get your power band back up. Fordman311 it all depends on what you want to use your truck for, Towing, hill climbing, everyday driving ect...??

 

Gearing is simple. There is no such thing as too much but you do have to know what is going to happen and what you have to do about it. There are two basic reasons for changing gears. "A" you want to maintain the same performance but use bigger tires or "B" you want to improve performance. "A" is the easiest, just measure the circumference of a stock size tire for your vehicle (you might not have stock size tires at the present time but thats what you have to use) Cstock=3.14xTirediameter. Then measure the Cnew for the tires you want and divide that by Cstock. You will get a number bigger than 1. Multiply that new number by your present gears and you get the number for the new gears you need to maintain the same performance. This new gear number will not be exactly what you can get. You will have to pick the closest ratio that is available and stay within +/-5% or you will mess with the computer's program. Example: Cstock=3.14x31"=97.3 Cnew=3.14x35"=109.9/97.3=1.13x3.55=4.01 so changing from 3.55 to 4.10 gears will allow you to use 35" dia tires and maintain performance. "B" is more expensive because you must find a way to correct the speedo and the results are not an exact formula but they are dramatic. My '97 F150 5.4L E4OD 4x4 with 3.55 gears at 55mph was cranking 2300rpm in 3rd and a pitiful 1650rpm in OD which was basicly useless. I was towing a 7000# gooseneck horsetrailer and miserable. Against all the conventional wisdom (Ford and Others) and with a written disclaimer from the machine shop saying they were not responsible for my stupidity, I insisted they install 4.56 gears. Both diffs $1100. Speedo fix $150. Tremendous improvement! I'm in the power band now at 55mph cranking 3000rpm and 2100 in OD which is okay on the level. Mileage went UP from 7-8mpg to 9-10mpg towing. These little gas motors need revs to get any power so up the freaking revs.