Any one with a F150 4x2 running 4.56 rear end gears?

 

Here is some info you need to know.
The trans has an over drive ratio of .78.
A. Assuming the present rear is 3.55 x .78 = a final ratio of 2.76.

B. Out of overdrive it will be the 3.55.
C. A 4.56 x .78 will = the same 3.56 ratio in OD.
Notice the same final ratio comes up in two different combinations?
You need a valid reason to make that big a gear change.

If for towing, the gear won't make up for the other lack of towing elements needed. If the weight is much over 6500 lbs. it will put the truck over the gross combined limit.

The 70 in the trans designation is 700 pound feet of torque max. rating for the transmission.
The average engine torque for a 4.6L is about 265 pound feet.

At max torque point through the trans to the rear of 265 x 3.55 = 940 pound feet +/-.
Already over the rated limit of the trans but it does not see that amount of torque continuously.
Going to 4.56 x 265 would go well over 1200 pound feet.
If you have an electronic dash, the PCM would have to be flashed to get any near correct speed indication.

If not done, the shift points might be greatly changed.
The RPM will be much higher in all gears.

I bring you this info because it's not just a bolt in and go with out affecting other elements.
An example; pulling combined weight over 12,000 pounds blew the converter on my 4.6 lest anyone thought the 4.6 did not have enough torque to do that.

You do what you want but these are things you might run up against.
Good luck.

 

I orig had 3.55 gears. I swapped them out for 4.10,and was as impressed very little. It did make a diff. in acceleration ,but not as much as I would have liked. This is why I'm considering 4.56.

 

Nope - 0.70.

"Best" ratio depends on engine. A 4.6 will benefit from 4.56 but a 5.4 generally won't unless you lift it and put oversize tires on it.

 

I put 4.10's in my F150 and I'm happy with it's towing performance.

 

If I were to swap out my 4.10 gears for 4.56 I would be at 2651 rpms at 75 mph on the interstate. If you are a qualified person ,please share your thoughts regarding me installing 4.56 gears in my 2000 F150 ext cab 4x2 4.6 V8 4spd AOD

 

Need the following info from YOU:

1. What type of driving do you do with your truck?
2. Do you tow with it?
3. What mods have you done to the truck?
4. Is the suspension stock height?
5. Are you running stock tire size and type?
6. When you put the 4.10's in, did you reprogram the PCM for the different ratio?
7. Are you running a stock tune?
8. Do you care about gas mileage?

 

1- In town driving. Tow a trailer 2 days a week in town weighs approx 1800 lbs.
2- performance mass air,cold air intake,75mm throttle bodymsct x4 perf. promgrammer 93 ocatane,true dual exhaust borla mufflers
I am about to install headers,electric dual fans (flex a lite), and underdrive pullies.

3- I have lowered the truck front and rear. Maxtrac suspension

4- Yes the PCM was reproed with the sct x4 programmer to my 4.10s
5 - care care about mileage to an extent,but I like power!

 

What I would do is finish doing your mods, then get some CUSTOM tunes written for you by a good dyno shop or good online tuner, see where you are at. If still not happy, then consider 4.56 or even 4.88 gears.

Note that a 4.6 does not have that great low end torque no matter what you do to it. Your mods are all more biased toward horsepower, which is not what will get a relatively heavy vehicle moving.

I'd seriously consider doing a 5.4 swap.

 

4.56 seems pretty aggressive! if you are running little tires too!

I have a 4x4, with a 5,4L, and 35" tires, and the 4.56s are pretty nice