Here are the specs-- 98 f150 SuperCab 2 wheel drive with 56,000 miles on the 4.6. I have 3.55 gears with 255/70/16 tires. The truck is my daily driver; about 15 miles round trip to work, and I use the truck to pull my racecar (Mustang Coupe) about twice a month.

Here are the problems--the truck is a turd power wise and it gets crappy gas mileage. It shifts every time I come to a slight grade, which is good because if it didn't downshift it probably would stop in its tracks.

I want to upgrade to either 3.73 or 4.10 gears to improve the towing and overall performance of my truck. I don't know if the 3.73s would be steep enough to tell much difference and I'm afraid the 4.10 may be too much for highway driving as well as kill my less than stellar gas mileage. Also, how do I recalibrate the speedo after the gear swap?

I need the opinions and experience from the members here to help me with my decision. Any and all comments will be appreciated.

Thanks,

Eddie

 

Eddie,
It sounds to me like you def need to go with the 4.10's. I installed them in my 97 with 4.6 and it was a night and day diff. Overall it turns about 300 more rpm than it use to. you would not notice any diff with 3.73. Yes you have to change the speedometer gear. No big deal only $8 and takes 2 min to change. Gas mileage is 15 around town and 18 on the highway. Only diff is that i have 20" rims. If you are worried that 4.10 is too much then think about 3.90. If i were you i would go 4.10 since you do some pullling.


-K&N GenII
-3" Flowmaster
-4.10 Ford gears

 

3.73 with the tires you have now.

You could get some improvement if you went with the Standard 235/70/16 tires, and stuck with the 3.55. The problem is that the 255s look good in the wheel wells.

My thoughts. I don't tow much, but I know if I did I would like to have the smaller tires.

 

My truck originally came with the 235/70/15s but I have a friend that works at a conversion company and gets 'take-offs' dirt-cheap. So when it was time to replace my tires I bought a new set of '02 wheels and 255/70/15 tires for the price of one tire. After the tire and wheel swap I really noticed the drop in performance and fuel mileage. Currently, I'm leaning towards the 4.10s mainly because I don't feel the 3.73s will make a noticeable difference for the time and trouble and I already have a set of Motorsport 4.10 gears. If I didn't have the 4.10s I'd seriously consider the 3.90s over both the 3.73 and 4.10s.

As of now my truck is completely stock, but after the gear swap I may go with a FIPK and a free flowing cat back. I’ve considered a chip but I hate the thought of having to buy Premium gas with every fill-up. That can get very expensive in a hurry.

Will there be any adverse affect on the tranny with 4.10 gears i.e., will it shift early or late, increase heat, etc.?

Thanks for the help.

Eddie

 

Hey 98redf150

Here is a web site, that may help. Your tire height is 30.06

http://www.4wheelparts.com/Tirel_Gea...AKHLV8EBQD8C87

 

A little more info

With the tires you currently have the effective gear ratio is 3.42

Your speedometer is off a little (shows 48.17 when you are really going 50).