what size gears 4:10 or 4:56

[Big Kel]

I have a 91 with 33s and a automatic trany, I was wondering what size gears would be best. Thanks for your help.

 

[madmike]

if your going to stick with the 33's then the 4.10's will be fine , but if you plan on the 35's then go with the 4.56's,

 

[jDan]

i have 33's and 4.56's and love em. I actually gain speed as I go up steep hills. It also depends on what size gears you were running before. If you currently have 3.73's going to 4.10's is not worth the money.

 

[leenjen]

how do you use your explorer. if it's a daily driver with a lot of highway, then stay with the 4.10s for the 33s.

 

[Big Kel]

How can I tell what my stock gearing is?

 

[Big Kel]

never mind i have a d4 or 3:73. So maybe 4:56 would be beter then. What do you guys think?

 

[jDan]

I use my rig as a daily driver. The only thing that I noticed with the lower gears is that it does limit your top end a little bit. But this is only at speeds above 80 mph. I don't have the need to go faster than that so everything is cool for me. While you're at it throw a locker in the front diff! You don't notice it untill you put it in 4 wheel drive and it makes a world of difference off road.

 

[mikeresin]

damn 4.56's
hope ya dont plan on going on the freeway

 

[hornz2000]

mikeresin,

keep us posted on the 90 GT i.e. any mods etc.

 

[mikeresin]

yeh i was going to add my mods to my sig but i figured no one would really be interested in the mustang.

so far on the mustang i have
2 chamber flows w/o tail pipes
bbk off road h-pipe
180* thermostat
black magik electric fan
bbk 190lph fuel pump
msd high output coil
msd performance wires
performance plugs
mac cold air intake
ford racing king cobra clutch kit waiting to be installed
for raceing adjustable clutch quadrant cable
water wetter radiator additive, dropped my temp 20 degrees
and thats about it for now.

im ordering up my nitrous in a few weeks.
not too bad for only haveing the car for 2 1/2 weeks
hehe ive been busy can ya tell?

 

[hornz2000]

Sounds real nice for 2.5 weeks...How much nitrous you gonna run...any plans for a blower or headers, etc.

 

[mikeresin]

ive actually decided to hold off for a little while on the nitrous.
when i do do the nitrous its going to be the venom vcn 1000 kit. ive already installed in on my buddies mustang and it works like a champ. the biggest fogger it comes with is a 125 shot.

right now im saveing some money for a Griggs racing setup: torque arm, pan han bars and high strength diff cover. installed and everything for $1000

after that its heads and cam and valves and lifters etc...

 

[Adam Berger]

I was also considering 4.56 in my EX, which at the moment has 3.73. I have 32" tyres and at the moment the car's offroad ability is apauling. Everytime I go down a steep track, I'm always on the brakes. My question is, would this gearing help? Also, I have a 5 speed auto so would this mean the RPM on the highway would still be ok?

 

[Robert]

To put my RPMs back to stock when I had my 30" tires with my current 32" tires I would need a 4.37 axle ratio. Due to the increased weight from the larger tires, a 4.56 would be a good match. Multiply your current RPM by 1.22 to get your new RPM with 4.56 gears. My 4.10 is still a good match for my 32" tires though. If I went any taller, I would likely swap out to a 4.56.

Do you have a low range? If so then 4.10 would be OK when off-road. If yours is AWD or 2WD then the 4.56 will be better when off-roading since you lack a low range transfer case.

 

[Guy Groves]

What do you expect out of your re-gearing:
Do you want fuel economy?
Do you want stock perfromance?
Do you want better 4 wheelin performance?

There is always a compromise. If you want fuel economy you lose power. If you want wheelin power you lose fuel economy.

Go to this site for some helpful calculators and gear ratio/ tire size information thatmay help you.

http://www.mtv411.com/auto/Axle-Tire-Ratio-Calc.htm

 

[Adam Berger]

Since I put my larger tyres on, my fuel economy has been bad. I'm lucky to get 500km to a tank (80L). I assumed that lower RPM on the freeway would be beneficial to economy but I don't think it is in my case. At 100km/h my RPM is 1800-1900, which I think is too low and below the engine's power range. This would make me use more fuel to maintain speed. I think the change to 4.56 gears would give me at cruzing speed, an RPM around 2300-2400. And yes I do have a transfer case so in low range I should be able to crawl down hills. I should get the best of both worlds in theory.

 

[Robert]

Fuel economy will only get better to a a point when your RPMs get lower. My Explorer got the best fuel economy it ever got with my cruise control set at 80 MPH for a tank of gas. On that tank I got 20 MPG. When I average around 70 MPH I usually get 18.5 - 19 MPG. When I swapped my 30" tires to 32" tires, my fuel economy didn't change by any noticeable amount. It also works the reverse too. If your RPMs get too high, then you will get worse fuel economy. There is a happy medium you have to fall in. If you get too low below the optimum power band, you will burn more fuel and increase wear on your engine as it lugs. If you go too high above the optimum power band, you will burn more fuel and increase wear from the higher RPMs. For a 32" tire both a 4.10 and a 4.56 will work well and give acceptable mileage. You will feel more of an improvement with the 4.56 than the 4.10 since it is more of a change. The mileage difference proably won't amount to more than .25-.5 MPG. I doubt if it is even that much. Unfortunately it would be far to costly to find out.

 

[ld50]

My 2 cents fer ya

I got 4.10s in my Ex, which I got after much deliberation and research on the boards

I want it to be good up to a 32 " tire, but have 31`s on now. My feelings are that 4.10s and 31 inch tires is just perfect, and going to a 32 inch tire when these wear out will not make too much difference.

If, however, I wanted 33`s on, I would go for the 4.56 gears. I like torque more than fuel economy anyway..

Tough decision, because once you start modifying, you want everything to keep getting bigger. Who knows, you might want to go bigger than 33s one day and find that 4.10s are not enough
Burn the extra gas now or pay for new gears again later, hmmm....