hows it going,
Well looking for some more *** in the back and was wondering if any one has changed there gear out in the back. My truck is a 2001 f-150 with the 5.4L, I have the 3.55 right know and the takeoff sucks from a stand still. Does any one have a 3.73 or a 4.10, whats you rpm at 70 mph, I do some long drives everyknow and then to the deer lease, but also alot of short driving, any help would be great.

 

for the price of installation and parts, i dont think its worth it going from 3.55 to 3.73. the difference youre gonna feel in acceleration wont really be worth the cost, so id suggest going to 4.10. the down side is that you will be burning a little more gas in the highway (turning higher rpm's). hope this helps, good luck!

 

A gear change of .25 or so doesn't result in much change in performance, especially for the money. Similar results can be done with tire height changes. To really notice a difference and to be cost effective, you have to make the change a minimum of .50 or so; in your case the 3.55 to a 4.10. The overdrive gearing allows plenty of top end speed and alot more grunt off the line.

 

Most definately the 4.10 gears. I test drove a 7700# F-150 a while ago with the 3.73 gears, and I couldn't really tell much of a difference between it and mine with 3.55's.

-Flea

 

About 2350 rpm @ 70 mph with 4:10 gears. One of my favorite mods to date! There will be a speedometer error however.

 

Flats Man - get Mike T to burn you a chip with speedo correction the next time you update your chip - this fixed my speedo error after going to 4.10's.

Ian

 

Ian, I am OK because I have a 98 4R70W with the reduction gear. A 23 tooth gear fixed me right up!

 

Ian N,

What size tires do you have. I've considered the 4.10's for my 00 Expy. I have the 3.31 gears. What is your cruzin rpm at 75?

Thanks

 

I have the 265/70-17's (31.5"). I get about 2300 at 70 mph in OD. Roll-on performance is great - it was a dog with the 3.55's.

Ian

 

4.10's!!!!!!!!!!!

2558 RPM @ 65 MPH SAWEET.

 

Go with the 4.10 and if the rpm's are too high to make you happy you could always go with a taller tire and that should bring the 4.10 back down depending on the height of the tire.

There are some calculators at www.4lo.com that may help in your decision.

 

Flatsman,
Where did you get your 23-tooth speedo gear? Everybody I've talked to said there was no such thing for an F150, and that one made for a Mustang would not fit. I want to put 4.10's in my '98 SC 4x2 Lariat. I know that Hypertech (?) makes a Power Programmer that claims to correct the speedo on only '98 models if the tire size or gearing is changed. So now I'm confused on speedo correction on my '98; do you correct it by a speedo gear change or electronically with a chip/programmer? I already have the gearset and am ready to install it, but I keep hitting this stump. What do I need to do on my '98? I welcome info from anybody. Thanks a bunch!

P.S. According to my calculations, with my 5-speed on 30" tires, I'll be turning about 2700 at 70 mph. Ouch! Glad gas is cheaper right now.