Hey I'm new at this whole lifting thing and I have a few questions. I've read a lot of threads and it seems everyone has a different opinion and all the forums get off of the topic and it's annoying lol. I just bought a 08 f150 5.4L flex Fual with the 3.73 limited slip 4X4. I've ordered a fabtech 6" lift with and add-a-leaf kit for the rear, and 20" ECO wheels with 35" nitto terra grappler tires. I am pretty sure I need to go with different gears for the axles but I'm not sure.. can I run the stock 3.73's or will I just kill my power and fual mileage? Should i go with 4.10's and be batter off with being able to tow and everything, I also plan on Gibson extreme duals and volant CAI in the future as well as the Jet plug-in module. any suggestions?

 

you could go with a 4:56 gear ratio ( i belive thats it) and that one should bring you back to stock, or a 4:83 for more power

 

I would go with 4.56, thats what I have... Maybe upgrade to a truetrac... Since you'll have it all apart...

 

I'd do 4.88, but I like to accelerate quickly.

 

You can get by with your stock gears unless you tow/haul a lot of heavy loads. If you regear, and it is a good idea, I'd go with 4.56's.

 

4.56's

 

Just curious... wouldn't gas mileage improve on the highway due to gear ratio causing the engine to turn less rpms? It'd be a trade off... worse gas mileage to get moving, but better gas mileage once moving.

As far as weight, you're trading 5 wheels/tires for 4 so weight wise you may be alright... but of course, you have more rotational weight which obviously makes more of a difference than total weight when it comes to power/gas mileage.

 

Gearing is a compromise. If the truck is geared too tall, the engine will be in a strain and lug, causing poor gas milage. If the truck is geared too low, the engine will turn too many rpm causing poor milage. The factory tries to find the ideal compromise and usually go on the tall side with gearing. Therefore, mpg's usually go down when you install a taller tire.

 

Different gear ratios were offered from the factory... I'm sure guys with stock setups in the 2.xx are getting better highway mileage than guys with stock setups on 3.73s. The trade off, the 3.73 can tow a load a bit better... I don't tow anything heavy at all, or anything at all really, and I have 3.73s... so do you think I'd benefit from the different ratio? I was thinking going from:

Stock = 265/70/17 = 31.6x10.4/17

To:

315/70/17 = 34.4x12.4/17

A different of 2.8 inches... how much of a difference do you think it would make weight wise, and ratio wise?

 

4.56's

 

ok so hlp me with this one. "99" 150, with the 4.6, i have a rather large lift (11inch front,12 back) and i'm gonna stick 37s under her soon, i still have stock gears, but i still travel a bit to and from work(highway) , but i also tow stuff all the time in the summer, (4wheelers,pop up camper, scrap metal, no more then 4-5000pounds) what should i change to? 4.56,or 4.88, 4.11(do they have 4.11?)

thanks Junior

 

37" tires + 4.6L = 5.xx. Looks like 5.14 might be availible. The 4.6L likes to sing.

 

Where is a good place to pick up these gears? whats a good brand? and is it something simple to do?

 

APT


Likes too sing?? 5.14, you mean the 4. ... will not do?

 

4.88 is the tallest I'd go, which is probably more common. People with the 5.4L are happy with 35" tires and 4.56 gears. OP wants even larger/heavier tires with a less powerfull engine. The 4.6L makes its peak torque from 3000-5000rpm, so let it sing