How do gear ratios in 4x4 work????

[Surrey]

It could work but you would need to put the bigger tires with the lower gears, or in front in your example. For instance if you did have the 4.10 in front and you ran a 31" (stock being about 28") tire then that would bring your actual ratio down to about a 3.70. And that could ideally be close enuf to match the rear 3.73 gears.

Its late, I've had a few beers, and math is beyond my grasp at this point... So if I had 3.73 gears up front, with 31x10.50, what size would I want/need in the back for 4.10 gears?

edit - if my math is right, I get something like 3092 for the front,31" circumference x rear ratio.... And like 3188 for 33" circum x front ratio... So a difference of 3.12%.... Too much?

 

[bmob]

This was a hypothetical question, I assumed on the end of mashing T-case gears but wanted to be sure (I always hear about people saying "I finally got 4.10 gears in the front" and then asking myself if they have 4.10 in the rear already of upgraded that at the same time too). Now for a more realistic question. Could you run a locker only in the front while having an open diff in the rear?

 

[xkotyx]

This was a hypothetical question, I assumed on the end of mashing T-case gears but wanted to be sure (I always hear about people saying "I finally got 4.10 gears in the front" and then asking myself if they have 4.10 in the rear already of upgraded that at the same time too). Now for a more realistic question. Could you run a locker only in the front while having an open diff in the rear?

yeah you can. its much more convenient to put a locker in the rear. if you put one in the front itll limit your turning alot and make it pull the grooves in the road more

 

[bmob]

wouldn't it only limit your turning when in 4x4? or would it limit your turning whenever the hubs are locked in? and i ask this because i got stuck the other day (horrible feeling) and just helplessly watched my passenger side front tire spin and my driver side front do nothing

Now of only I had the $$ for some wheel travel i probably wouldn't have gotten stuck (too bad 408 strokers like to eat paychecks like they do gas )

 

[88_Eddie]

Its late, I've had a few beers, and math is beyond my grasp at this point... So if I had 3.73 gears up front, with 31x10.50, what size would I want/need in the back for 4.10 gears?

edit - if my math is right, I get something like 3092 for the front,31" circumference x rear ratio.... And like 3188 for 33" circum x front ratio... So a difference of 3.12%.... Too much?

i think the lebatt's are getting to you. if you had a 3.73 up front, you'd want a 3.73 out back. the tire size wouldnt make it ok to run a different gear ratio. it would still F up the t-case.

we need a diagram that we could post for this question, i've seen a few threads on it lately

 

[kunar]

i think the lebatt's are getting to you. if you had a 3.73 up front, you'd want a 3.73 out back. the tire size wouldnt make it ok to run a different gear ratio. it would still F up the t-case.

we need a diagram that we could post for this question, i've seen a few threads on it lately

no, no.... by running a taller tire and a lower ratio, the distance traveled each rotation will match the other axle with a higher ratio and a smaller tire. obviously the difference in tire size has to be in proper proportion to the difference in gear ratio. how do you think tractors run 4 wheel drive with those little tires in the front and the tall tires in the back?

 

[adsm08]

I've personally never broken a transmission extension housing,

I've seen a few extension housings broken, but it was usually caused by either hitting something with the case while not having a skid plate on, or hitting something with the front diff while having the wrong front shaft in.


I also had to replace an E4OD in an Excursion a few weeks back. The case was cracked in two around the second from last pan bolt. Best we could figure it was caused by the oscillation from the bent drive shaft.

 

[adsm08]

i think the lebatt's are getting to you. if you had a 3.73 up front, you'd want a 3.73 out back. the tire size wouldnt make it ok to run a different gear ratio. it would still F up the t-case.

we need a diagram that we could post for this question, i've seen a few threads on it lately

Surrey and Kunar are right. The bind comes from differing final drive ratios at the tire. If you match your tires and gears so that the final ratios are within .05% you are good. Running the same gears and different tires will cause as many problems as different gears and the same tires. That's why on the AWD cars you HAVE to replace all 4 tires as a set or it causes AWD system issues.

 

[Surrey]

Surrey and Kunar are right. The bind comes from differing final drive ratios at the tire. If you match your tires and gears so that the final ratios are within .05% you are good. Running the same gears and different tires will cause as many problems as different gears and the same tires. That's why on the AWD cars you HAVE to replace all 4 tires as a set or it causes AWD system issues.

Thats what I was thinking... But .05%? really? That seems like a rediculously tiny ammount of variation?
thats like 1/2000