mixed thoughts on 4:56 gears...
 

for the longest time now ive wanted to get the 4:56 gear setup, i have people who say launches will be excellent , more torquee....etc... i then talk to my mechanic the other day who builds these old mopar cars from ground up and i told him i would be purchasing these gears very very soon and having him install... and asked me why i would go with such a big gear size for the truck?? and tells me exactly what everybody else has said on this site, and that is that first off, from 70 mph -100mph your gonna lose that power and second, i have a manual trans so i would be shifting at 20 mph, and shifting a lot more than i have to ..ultimately he said a gear size between stock ( my guess is 3:55's?) and 4:56 would probably be the best ....what is your thought on this?? i think he does make a good point... i do have a manual trans and one positive would be my fricken launch will be huge! then i look at myself shifting 2-3 times just to get to the speed 30 - 40 mph . all experts please give me your suggestions! im about to purchase gears from the one and only www.airram.com !!

i agree you should listen to the mechanic i believe i will try to find some gears in between because i do a decent amount of highway driving

How tall is your tire? That makes a difference too.
I run 3.55's in my Mustang with only a 26" tall tire and it kinda low, but the truck will have a much taller tire. First verify what gear that you have now and then see what your tire Diameter is and we can go from there. Maybe a 4.10 would be better for the manual trans.

I will say it again... DO THE MATH... I provided the math formula for you to use... its simple math.

USE the formula for each of your gears in the transmission. This will allow you to learn at what speed each gear will be good to.

I must clear up that in no way in gods earth will you lose POWER at 100MPH... your engine will have more mechanical advantage to push your brick shaped truck through the wind with much less effort... I would predict your 1st gear at WOT would be quick but not is a bad way... and your 2nd gear will be fine... I highly suggest you speak to those who have actually done the swap. I had a customer with the same transmission, he went to 4.10's and for the most part was happy... but he still says "I could have easily gone to 4.56's and would have if I knew what I know today" Hind site is always 20/20... But again, ask around... check out D.o.d.g.e.t.a.l.k.c.o.m. and ask around... but separate the OPINIONS of people who have not done the swap from the FACTS from those who have done the mods.

But again... take the 10 minutes and do the math!

SPEED SAFE, AIR RAM

Your absolutely correct!

Tire height and overdrive gear ratio are two of the most important factors when choosing a rear gear. Like I mentioned before... too many people are stock on the REAR GEAR RATIO and not what they should be stuck on, the "OVERALL GEAR RATIO"

SPEED SAFE, AIR RAM

keep talking to this mechanic
he seems to be honest, knowledgeable
and seems to care about giving you value for money

don't stop there
ask this mechanic what other
knowledgeable 'old timers'
are near you
that you could discuss things with

everybody thanks for your advice and i guess next step would be to find whats stock.and lol airram i have seem the table in another thread so ill try to find it.

Even with your mods, I would bet the 4.7 is to small to gain any real advantage with 456 gears. I too have a 6sp in my 2500 ram with the hemi with a 373 ltd slip, Most Ram 1500's have a 392 gear set.

If your 6speed with the 4.7 is geared for torque, your not going to gain any acceleration, the 4.7 will be bouncing off the rev limiter to drive the 4.56, their goes the stock clutch...

The 6speeds in the Rams are not built for drag racing, A SRT Ram is what you should be playing with for your performance goals..

This is what kills me about this forum- you've got a bunch of guys with slow trucks telling you how to make yours fast. Then along comes someone with a fast truck (airram) to tell you what to do, and you get Mr Propane Salesmen telling you to listen to "old timers."

Do you own an old time truck or a new one? Does it have an old time carbureted engine, or a new computer controlled port injected motor? Does it have an old time trans or a modern trans? Who cares if some guy has been working on cars from 1972? I want someone that knows about modern performance.

"Old timers" always so no to 4.56 gears. That's because they remember when cars had "3-in-the-tree" and "4-on-the-floor". They didn't have massive overdrives and tall 5th gears. Back then 4.56 would kill you on the highway. That's just not the case anymore. It's time to move into modern performace. Heck, there are guys with ricers blowing away those old 70's hotrods and you can be darn sure they're not getting their advice from "old timers" on how to do it.

there are two schools of thought
about how to select
overdrive ratio

the 'dominant' way it is today
is that nearly all the automakers
select the 'highway cruise' overdrive ratio
that allows the 'normally loaded' vehicle
to climb 'normal' hills on the
Interstate Highway system ( about 4% grade)
without a downshift by the transmission
(some customers hate downshifts)

The above approach results in slightly less MPG
on level or downhill highways
or when the vehicle is nearly empty and light in weight

The old school of thought
on Overdrive ratio choice
was that you choose the ratio
that gives the best MPG on almost level highways
and you expect the transmission to downshift on hills

In this 'best MPG' type of overdrive
you select the
engine piston speed to be between
700 to 1100 feet per minute and the
MAP sensor level to be about 70% to 80% of atmospheric pressure
and then you make the engine enough cubic inches of displacement
to provide the hp needed
to overcome aerodynamic drag and tire rolling resistance

This results in the best fuel economy
but the vehicle usually can't climb more than a 2% grade hill
and does not have very much reserve of 'passing power'

CVT transmissions are attempts
to have the best of both