Does anyone know what speedo gear....

[Lifted93XJ]

I got pulled over today for speeding and my speedometer said i was doing 45 miles an hour and i was pulled over doing 55. I have 255/75/17 mud terrains on Rubicon wheels. It is an automatic trans with a 231 transfercase. Do any of you know a calculation or know what tooth speedo gear i would need?

[bigazxj]

what gear ratio do you have?

[stewie]

use your axle gear ratio and your tire size to find out on http://www.go.jeep-xj.info/HowtoSpeedoGears.htm

from what you said and ASSUMING a stock gear ratio:
255 metric tire (30.0"), 3.55 gears= a 33 tooth speedo gear to get you back to approx correct.

i cant remember what the stock one is. i have swapped mine out a year ago for when i will be set on 33s

hth

ps: if you dont already have gojeeps site bookmarked on your comp, it may be a good idea to. i have found his site to be increadably helpful.

[RoXJok]

:yelclap:Sweet!! Thanks for the link!! I've been needing to change my speedo gear for some time now. I'm running 33" tires with 4.56 gears. Thanks to the ink I can figure out what I need al by myself!

[live24wheel]

Last I heard, you guys are going to hate buying a new speedo gear. Correct me if i'm wrong but didn't they go from around $15 to over $100 at the stealership?

[RoXJok]

I don't know. But I know my speedo says 70 when I'm reay going around 50. No bueno!!

[stewie]

I don't know. But I know my speedo says 70 when I'm reay going around 50. No bueno!!

i dont know if he still does, but gojeep used to sell the white faced guage inserts (lays over your existing guage face) and he had some models that the marks were "adjusted" to correct that type of issue. again, i am not sure if he still does or not. you would have to check his page and i am too lazy to do that right now.

[bigazxj]

let me know what tooth count gear you need and i can get you a great price on it that goes for anyone here who needs one

[Virgil-K7AZV]

I have a 30 and 34 tooth gears at home if anyone wants those. I think the 34 was the stock one with 3.55 gears.

[mike37]

let me know what tooth count gear you need and i can get you a great price on it that goes for anyone here who needs one


I need one but I have a 91 np242 and the gear connection looks nothing like the one pictured
it has some funky offset thing on it

I just check today by GPS and im off by 8 mph at 45

[IH8RDS]

I let my son drive my jeep when he was in town (4.46 gears and 31" tires) and he was wondering why everyone drove so fast out here. ;)

[stewie]

I... (4.56 gears and 31" tires) and he was wondering why everyone drove so fast out here. ;)

x2 for me for the time being

[Sc00by]

:yelclap:Sweet!! Thanks for the link!! I've been needing to change my speedo gear for some time now. I'm running 33" tires with 4.56 gears. Thanks to the ink I can figure out what I need al by myself!


I too had that same set up, Now on 35" :confused1

4.56 & 33" youll need a 37 (if I remember right)
And go to Absolute Offroad and talk to Joe!!!!
them gears arent that costly! and are quick to change out!:patriot:

[Shogun]

GoJeeps chart is pretty good, some others are not so. These days theres no reason not to use GPS for the calibration, borrow one if you have to. Remember they only update every half second or so, so what you are looking at is historical data, try to keep a constant speed while calc'ing.

Drive GPS speed of 50mph. Read as accurately as possible the speedo, take the difference from 50 and double it. Thats the percent error of your speedo.

IIRC, each tooth is worth about 3-4 percent. That might be on someones webpage. The chart is approximate, it got me within 3% of true, now I need to change from 35 to 34 tooth, I think. Someone sells used ones for cheap, again probably via a GoJeep link.

SK

[cwstnsko]

34 and 35 tooth are pretty common in the 4.0l, auto XJs in the junkyard. A 5spd might have a 32 or 33 if it has 3.08 gears. 4 cylinders will and V-6s will commonly have bigger gears, more useful for those geared lower than stock. Grand Wagoneers commonly have 30 and 31 tooth gears for those who have gone to 32 or 33" tires without re-gearing. I haven't checked the Dodge stuff, but it could be a good source of different gear sizes. The gears we are looking for are fairly common, the junkyard is a smorgasborg. I picked up a pile of different gears for $10 at the Mesa Pick a part the other day. If any one is looking for a 34 or 35, I have a pile of those, long and short. A 33 tooth made my 231, 3.55 geared 245/75R16 dead on, for some reason it took a 31 to get Adventurr's 242 Wagoneer on 31X10.50s just right, makes me think he might have 3.08s ??

just a note. 231s and 242s don't generally spit fluid on you unless you just parked it. give it a minute to drain down and stay cleaner :) Other t-cases in the yard will commonly blow oil on you, position your body accordingly :) Gears can be moved from a short shaft to a long shaft by driving the shaft out with a punch, but be gentle and support the gear well, they can crack fairly easily. A little soaking in boiling water might make it a little less brittle.