i have an 03 qc 4.7, it has 35 in tires, and my only mod is a flowmaster exauhst. I hate driving on the free way for the reason that i dont seem to have enough power to stay in over drive, it constantly down shifts, than up shifts. with tires this size what results can i get from having it regeared

 

you really should regear. you will pick up lost power and gas milage. as far as what ratio to go with? i am not sure.

 

Are you a 2WD or a 4x4? If you are a 2WD I would get a set of 4.88 gears... they will be the PERFECT ratio for your combination!

If you have a 4x4 you will be stuck with the 4.56's which will also be a GREAT gear.... but with your 35's I think the 4.88's would be a little better.

SPEED SAFE, AIR RAM

 

I know there are tons of guys putting 4.56s in the 4.7s and loving them. I went with 4.10 in my hemi and its low enough for me, but either one and you will stay in overdrive.

 

yeah i have the 4x4. what did you guys pay to have your trucks regeared? what gears come stock on the 03 4.7 4x4?

 

It's 3.93 if you have posi. At least that's what my 03 4.7L is. I think it's 3.55 if you don't have posi.

 

My 2002 came with a POSI 3.55 rear... You will have to look on your window sticker, glove box, or on the rear axle itself (either end) to find out what you have. If you have a POSI it will say ... 3.55LSD or 3.92LSD

SPEED SAFE, AIR RAM

 

Yeah my truck has 3.55LSD in it, and I NEED to get the 4.56's because I have the same problem that you do.. And I also have 35's... AIR RAM you think 4.88's are a better gear? What if you do a lot of freeway driving on long trips?

 

Whats your tire hight?

Here is the formula (Its REAL SIMPLE MATH):

REAR GEAR RATIO x Overdrive transmission GEAR = OVER ALL GEAR RATIO

SPEED x OVERALL GEAR RATIO x 336 / TIRE HIGHT = RPM

For best OVERALL performance (& fuel economy) you should aim to have your RPMS as close to 2000-2400RPMS @ 60MPH.


SPEED SAFE, AIR RAM