So I finally figured out that changing the gears in my 01 XJ will help it do a little better at highway speeds (post 3" lift and 31's). However I'm kind of torn on which gearing to go with. According to an online calculator I found, going from 28" stock tires to 31's with an initial gearing of 3.55 would require the new gearing to be around 4.05. I have been looking at bumping up to 32's or 33's, so I guess my question is if I should go with 4.10 or 4.56 gearing now so that I don't want to change it again with bigger tires? Thanks in advance for any advice!

 

Anyone have any ideas? Thanks!

 

i asked this awhile ago and i think everyone said 4.56 for 33s was proper but alot of people were running with 3.73 fine.

i have 31s and am trying to go up to 3.73 because when i put on a bored out throttle body, it made it as fast as it was stock so if i go to 3.73 i should be great. i currently have 3.55.

i would like 4.10 though but they are harder to find

 

Here is a link for you to 4.10's and 4.55's. These are what I was looking at I just don't know if going to a 4.55 with 31's currently would have any negative effects (i.e. great high speed power and terrible low end? just wondering b/c I'm still a complete newbie when it comes to this)

http://rustysoffroad.com/mm5/merchan...egory_Code=RIN

This is on sale too..

 

Oh yea one other thing; Will the limited slip unit that is in the rear dana 35 on the 01 xj's affect the installation of the new ring/pinion? Thanks!

 

It's a toss up if you go with 33's. I run 4.10's with 33's and sometimes wish they had just a bit more gear but with 32's they were perfect. 4.56's and 31 are going to have you turning 3460 rpm at 70 mph while 4.10's and 31's will turn 3111 at the same speed, assuming you have the AW4 automatic. If you go with 33's the figures are 3250 @ 70 for the 4.56 and 2922 for the 4.10's.
Good luck!

 

Cool thanks for the info! Looks like I will be going with 4.10's...

 

I'd say 4.10s would be fine. I run 4.56s, had them with 33s and now 35s and sometimes 38s and they work fine.

 

The fact that you have a PBR can as your picture is enough for me to take your word for it...lol. Any input on if the Trak lock in the rear axle will affect a gear install?

 

Don't see any reason why the trac lock would make any difference but while you have it out check the clutch pack. It may not be a bad idea to change them out since they tend to wear out after about 70k. Not sure which rear axle you have but the since you have 3.55s now the carrier for a D35 works with 3.55 to 4.88 and the 8.25 doesn't have a carrier break so you will be able to reuse whatever you have.

 

if you want it to drive stock then it would be like this:
stock tires-355
31s-373
33s-410
35s-456
but also keep in mind that as tires get heavier a little more bottom end is helpful. im in the middle of regearing to 456s on 33s

 

just put 4.10's in mine i run 33's and love it ,don't have to down shift goen up a small hill no more

 

Just divide stock tire size into new tire size and multiply that number times 3.55 for the new gear ratio that will give u the mathematical equivalent to the factory mechanical leverage.

31" (new tire diameter) / 28.29" (stock tire diameter) = 1.096 X 3.55 = 3.89 ratio
33" / 28.29" = 1.166 X 3.55 = 4.14
35" / 28.29" = 1.237 X3.55 = 4.39

 

4.10's sounds good for 31's. But, if you plan on going bigger in the future, I'd go 4.56's and call it a day.

31's on stock gears isn't bad at all, I'd deal with it until you go bigger honestly. That is, if you are going bigger, if not, void my response.

 

I imagine that 33's are probably about as big as I plan on going with this jeep so from what I'm hearing 4.10 is the way to go. Thanks for all the help everyone!