Explain to me the concept of gears

Alright i'm going to sound like a big Noob but thats because i am, we all have to start somewhere... Anyways, I would like to know how gears work and how will they affect my performance? I have no idea what you guys mean when you say 3:55 gears, 3:73, 4:10.... which is better? and does higher mean better? I really have no idea when it comes to this, so if somebody would like to introduce me to this subject it would be highly appreciated and take in consideration that i don't have an engineering degree.....thanks in advance

Ps: Which gear would you recommand me for my 1992 LX 5.0 with AOD

Differential gear ratios are determined by finding the ratio of teeth in the ring gear compared to the pinion gear (with the pinion gear having the smaller number of teeth). Gear ratios for most popular differentials are almost unlimited, and can run the gamut from around 2.56:1 in lightweight econoboxes to about 8.00:1 in large motorhomes and heavy haulers. But we're not interested in either of the two extremes; we're interested in the gears designed for street or off-road performance: 3.50:1 to 5.38:1.

Lower-geared/higher numerically, refers to a gear ratio that puts more power to the road by causing the engine's rpm to be greater per each revolution of the drive wheels. This is more torque multiplication than with a smaller rear-gear ratio. It allows for more towing capacity (as in towing a boat, travel trailer, or hauling a heavy load) and faster acceleration through application of more torque.

As an example, let's take a gear ratio that was once called the "six-cylinder gear" (back when everyone wanted V-8 power): 4.10:1. To make this simple, we'll use a transmission gear that's straight-through, or 1 to 1, which is usually Fourth gear in today's five-speed overdrive manual transmissions, or Third in a four-speed automatic. For this exercise we'll also ignore the tires' diameter because we're just talking the rpm of the various components, not miles per hour or mileage. With a 4.10:1 ratio and an engine that's twisting at 4,000 rpm, the drive wheels are turning at almost 976 rpm, or 4,000/4.1 = 975.61. This is why the differential gear ratio has a great deal to do with a vehicle's top speed. Lower gears mean lower top speeds; the vehicle is limited by an engine's maximum rpm. Lower gears, however, also mean that a vehicle will get to its (lower) top speed more quickly because the engine can overcome the vehicle's inertia easier with greater torque. Obviously, the tires play a big role here, since larger tires change the final gear ratio. (For example, a dragster's tires grow as their rpm increases, which changes the gear ratios for a higher top speed while still giving the higher torque off the line.) Larger tires can also increase drag or rolling resistance, but that's another story.

Now that you know what "lower/higher numerically" and vice versa mean, you have to decide whether you want better low-end tug (low gears) or higher top-end performance (higher gears). You may want to improve mileage, which means in most cases higher (numerically lower) gearing, or improve your 0-60 sprint with lower gears (numerically higher). Axle gearing is a crucial part of the performance package, and it determines how the engine's power is put to use

Differential Gears: The Optimum Choice (http://advanceautoparts.com/english/youcan/html/pht/pht20011201rg.html)

Not sure why he left out the fact that for you go with a bigger or smaller tire it will change your gear ratio?

For every 1" of change, you can increse or decrease your final drive ratio. Meaning the stock Mustang rim is a 26" tire, so if you had a 3.50 and went with a 25" tire, your final drive 3.64 or a .14 increase, but this is not linear.

For an auto, 4.11 for all out perfomance, but that also depends on the engine, and where the power band is at. To say all auto should run 4.11s is a fallacy.

Go here and play with the numbers, it will make better sense then :) http://kowboy1.bananaman.com/xycool/dragperf.html

Alright, thanks for al the information it helped me alot. I did my own research and it seems that alot of people are suggesting the 4.11 gears for a relatively stock mustang but if i were planning on supercharging or doing major mods to go with the 3.73 gears. I am not planning on doing extreme mods so it seems that the 4.11 gears are the best choice for me, and to be honest i dont really care if it reduces my top speed because for the times that i go 130mph + are really really rare and kind of stupid especially on a public road. I think i will go with the 4.11s for my auto mustang...any objections why i shouldn't?

Oh yeah, one more question, how will gas mileage be affected???


Thanks

Just to make sure, 4.11 gears will fit in my 1992 ford mustang 5.0 auto right? because i am ordering them. Just an other question, what website do you guys recommand for ordering parts? I am getting the ford racing parts because i want top of the line since i dont want to have rear end problem in the long run. So what website do you recommand other then ford racing.com?

Gas milage will drop, of course. :)

I hope you don't drive in the rain or snow!! If it's just a car for recreation, then you'll love them but, if it's a daily driver, I'd go 3.55 or leave them alone. But for fun 3.73's are great and 4.10's are even better!

I would get 4.10's.

it is a daily driver, well in the summer it is, i dont drive in the snow

I would go 3.73, 3.55 for a manual, but that is just me. Room to grow :D

so 4.10 is for manuals and 4.11s are for auto?

T-5 AOD (fox body) = 3.73 SN-95 T-5, T-45 = 4.10s, T-3650 = 4.30s

T-5 AOD (fox body) = 3.73 SN-95 T-5, T-45 = 4.10s, T-3650 = 4.30s


Uh....what???

it is a daily driver, well in the summer it is, i dont drive in the snow


You're not going to notice that much of a difference in RPM at highway speeds between 3.73-4.10. Maybe 200 RPM. Summer car....then go 4.10's. But you would not be disapointed with 3.73's either.

Uh....what???

fox bodies, with a T-5 and AOD (87-93; 5 speed and auto) go with 3.73 gears

SN-95 and new edge SN-95 (94-98/99-04) with a T-45 (5 speed 96-01.5) and the 4R70 (auto) and the S-197 auto (05-07) go with 4.10 gears, a T-3650 (01.5-07 5 speed manual) go with 4.30 gears

also

4.11 gears = 9" rear
4.10 gears = 8.8" rear

thanks you mustangman that's what i wanned to know

fox bodies, with a T-5 and AOD (87-93; 5 speed and auto) go with 3.73 gears

SN-95 and new edge SN-95 (94-98/99-04) with a T-45 (5 speed 96-01.5) and the 4R70 (auto) and the S-197 auto (05-07) go with 4.10 gears, a T-3650 (01.5-07 5 speed manual) go with 4.30 gears


I understand that 3.73's are the most popular, but why do you limit the 87-93's to 3.73? But like 4.10's for 94-95 5.0's and 96-04? Then recomend 4.30's for 05-06? Is it because you think with the Foxes low wieght they don't need anymore than 3.73? But yet with the heavier 94-95 & 96-04 you think they need 4.10? And then with the heavy pigs 05-06 I would agree they would need 4.30!! But 4.10 would still be plenty for the 05-06. Actually I think 3.73 would be great in any of them, but I would prefer 4.10's. Yes, I know the 4.6 likes the higher RPM's so maybe that's why you like the lower gears.

foxes have an OD ratio of .75/.72, you could do 4.10s in a 5 speed fox if you wanted oh and that inclueds the SN95 5.0s), but usually cause of the torque you go with 3.73s, the V-6s from 94-04 have a od ratio of .72 for the T-5 (same as the 5.0) and .70 for the 4R70 automatic, which is used in both the V-6 and V-8 engiens, the T-45 has a od ratio of .67 but is set up differntly then the T-3650 so it actually revs higher then the T-3650, so it goes with 4.10s, in mid way 01 they switched to the T-3650 tranny which has an OD ratio of .68 but revs lower then the T-45 can go with 4.30s, everyone i know with 3.73s said that they are not enough, even people with blowers

so a 5.0 with 3.73s = 4.6 with 4.10s = 01.5+ with 4.30s

I guess I have to agree with you but, for differnent reasons. I thought it was just because of the size of the cars that you preferred Foxes-3.73, SN95-4.10, and 05-4.30's. Which I would have no problem understanding that logic. I thought maybe it was something with the trans. also. I don't know enough about the differences in all the trans. so I thought I would pick your brain and I guess I got what I needed (good info). However, I've known many people and plan on doing it myself when I get another 5.0 (Fox) that had 4.10 with AOD and T-5. They all have said (for performance reasons) they would never go back to 3.73 and their RPM's on the highway only went up about 200, so NOT MUCH MPG loss for the MUCH better performance they've gained.

I do agree that the 5.0 Foxes have more torque and less weight than a SN95 (5.0 & 4.6) so they could do just as good or better w/ 3.73 vs. SN95 w/4.10.

the only 05-07s that should have 4.30s is the 5 speed, the autos have a shorter OD ratio (.72 i think not sure though) so autos should go with 4.10s and will be geared better then a 5 speed with 4.30s