Topic: 4.26 gears with 31's

[RT]

Hey, so I have a 2000 jeep wrangler tj MPFI 2.5 with about an inch of body lift and 4.26 gears, and I was looking to move up from the dinky 225's, the tires drive great but I have to row through the first 3 gears accelerating and honestly...my poor jeep looks like a little twinkle toes with the lift and 225's. However, I've heard that 4 cylinders dog out whenever you upgrade the tires even modestly and I was wondering how monumentally screwed I would b with 31x10.5 R15 AT's.

[neale_rs]

30s with 4.10 and later with 4.56 both felt fine (different but both acceptable) for me so yours will most likely run great with 4.26 and 31s.

[RT]

sweet, I just wanted to make sure I'll still have power and maybe save a little gas...I mean I'm reving around 3500 rpm at 70-75 mph 

[Torch_Ind]

what axles are you running to have these weird gear ratios?

[RT]

I'm pretty sure there 35c's, shit the person who had it b4 my have really gutted it, but I got my gear ratio's calculated and it's either 4.26's or maybe 4.56's (taking into account if my speedo's bo-yah! up)...I mean check it yourself, at 40mph I'm at 2000 rpm in 4th gear

[FourbangerYJ]

what axles are you running to have these weird gear ratios?

I was wondering the same thing.
Pretty sure he has the D30/D35 like the rest of them came. Pretty sure it has 4.10's not 4.26

If your gonna spend money and regear just go straight to 4.88's it's as low as you can go and will handle the 31 inch tire just fine.

[RT]

but the math doesn't add up for the 4.10's, if I had 4.10's I would be going faster than I am

[RT]

heres a link to a gear calculator http://www.grimmjeeper.com/gears.html   this is where I got my numbers

[neale_rs]

What tire diameter did you use for the calculation?  If you over estimated, this may be what is throwing you off.

[RT]

225/75 R15's, or 28.29 inches tall


sry guys, I could just be a stupid noob but I just had to check

[FourbangerYJ]

Check the axles for a small metal tag. Should have a bunch of numbers on it with the last set saying 4.10 or 4.56.

[neale_rs]

For the tire size, what matters is the radius to the bottom of the tire.  The weight of the Jeep will make is less than 1/2 the unloaded diameter. Probably 13.5 radius.

[RT]

ok, sorry to waste everybodies time, the tag says 4.11 but it's crossed out with a teal permanent marker

[RT]

but back to my origional question, how bo-yah! would I be with 4.11's and 31 rugged trails 

[Bounty Hunter]

Are you a comedian or is it Jeffy's profanity filter?  Maybe Jeffy's the comedian?

Sounds like you're not accounting for speedo error due to larger tires when trying to calculate your gear ratio.  I've never heard of 4.26 gears, they generally jump from 4.11 to 4.56, but for an oddball d44 ratio of 4.30 in some vehicles.