Weird question about gear ratios


#1

ok, so i was thinking the other day, about whether to go with 3.73s or 410s, etc… and in the process i was thinking about what they actually do…

if i understand correctly, the number means that is how many times the driveshaft rotates per wheel revolution, correct? assuming this, then it makes sense when you say they limit top speed slightly since that is basically determined by the rpm of the motor/tranny and how it is translated through the rear end. so at max rpm, the max wheel speed is less since with higher gears the wheels spin less per drive shaft revolution. so far so good.

my question comes in here - naturally when i read about gears and about how they give you more acceleration, i assume they would make bad weather driving real bad. this is where i am confused. the thing is, if you take two pretty mush identical cars, except one has (just for arguments sake, to keep numbers simple) 2:1, and one has 4:1 rear end gears. in the 2:1 car, lets say you try and start moving in snow and you just spin tires - understandable. but now if you take the 4:1 car, and lets say you give it the SAME RPMs (just by controlling the throttle carefully, i guess, and watching the tach) that you would have given the 2:1 car - the wheels will turn slower this time… wouldnt that be BETTER for getting moving?

make sense to me, but my instincts still tell me that 4:1 would be badddd in snow… am i missing something?


#2

reading too much into it.

Tip:

Don’t fear the gear


#3

mustangs are bad in snow. You are looking way to deep into this. Only two things you should focus on, is gas milage in 5th and about 1st gear. Im sticking with my 3.55’s because 25mins each day i drive to work in 5th and school so yeah.


#4

what does being in 5th have to do with it? i was told (by hrnb, for one) that long distance driving isnt really a big deal, even with 4.10s (in a v6)


#5

how bout having 4.10’s and starting out in 2nd gear in the snow… then your effective gear ratio would be less than the stock gears were in 1st


#6

i have an auto so i cant :dunno

by the way , i ask this in most threads about gears but never seem to get a good asnwer… what is a ‘cross shaft’? and what does it have to do with getting aggresive gearing… i keep seeing in diffrent places references to "needing a modified corss shaft’ if using 4.10s or higher in the 7.5"er…is that a big deal?


#7

its a rod that hold everything together in your carrier, removing it is the first step in pulling your axles for a gear swap. with larger gears sometimes the crosshaft, or crosspin, rubs or interferes with the rotating of the carrier so it would need a groove notched in it for clearance, either that or buyingn an aftermarket one thats been machined with a chunk taken out of it.


#8

do you know if the fordracing gears need that?


#9

doesnt matter the gear type on this one, its the gear size. I dunno, first time I swapped to 4.10’s some folks told me the same thing about the crosspin but I didnt need to do anything. reguardless its not a big thing, simply grinding down part of the pin where its rubbing is that’d need to be done.


#10

can i assume that the guy doing it would know about it? (andif he doesnt, then theres a problem?)


#11

he’d realize he’d have to do something when the carrier wont spin all the way around without hitting something


#12

i figured - what im worried about is if that happens and the guy says “hey those dont fit, go buy new gears”


#13

you can start in 2nd in an auto, just put it in 2 instead of D? thats what i do for the rain cuz i spin bad in rain- no snow in GA :banana


#14

as far as i know, if you put it in ‘2’, it just starts in 1st but wont shift PAST 2. i could be wrong, but thats what i thought it felt like when i tried it, and thats how a lot of autos are as far as i know

anyone know for sure?


#15

no cuz i have a “1” and a “2” and the “1” is at higher rpms and wont shift, then the “2” is like 2nd. you can actually shift through them, but i have no clutch so i dont :dunno i start in “2” in rain and dont spin, but i spin in D. so 2 has to be 2nd gear? :dunno


#16

Atlantic, Art is right about the Auto trans.
And as for you Art, Just buy the F’ing 4:10’s and be forever happy Art.


#17

so whats the diff b/w the 1 and the 2?


#18

1st, won’t let you get past first gear…2nd, won’t let you get past 2nd gear.


#19

yuppety yup


#20

[quote=HOTRODSnBOOZE]Atlantic, Art is right about the Auto trans.
And as for you Art, Just buy the F’ing 4:10’s and be forever happy Art.[/quote]

:smiley: im bad with decisions… at least i finally got the exhaust