stock gearing

ok i gots me a 94 xj stock 30 in front/35 in rear, i looked up specs, one site says i got 3.93 gears(not bad for what i do) one says i got 3.07, one says i got 3.54, i dont really care so much cuz i wanna put 4.11,quadratec told me i can switch my ring and pinion to 4.11 to get those gears as long as my stock ones are at least 3.54, does anyone know what i have, quad. told me get the numbers of my axle and a jeep dealer can look it up, i dont have anything(that i can find) on the rear, but i have a bunch of crap off the front, SOMEONE PLEASE HELP ME I WANT....NO, NEED 4.11 GEARS, but i dont wanna switch the acual gears!!! what do i have?

trashedxj said:

ok i gots me a 94 xj stock 30 in front/35 in rear, i looked up specs, one site says i got 3.93 gears(not bad for what i do) one says i got 3.07, one says i got 3.54, i dont really care so much cuz i wanna put 4.11,quadratec told me i can switch my ring and pinion to 4.11 to get those gears as long as my stock ones are at least 3.54, does anyone know what i have, quad. told me get the numbers of my axle and a jeep dealer can look it up, i dont have anything(that i can find) on the rear, but i have a bunch of crap off the front, SOMEONE PLEASE HELP ME I WANT....NO, NEED 4.11 GEARS, but i dont wanna switch the acual gears!!! what do i have?

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Without switching the actual gears? You sure you aren't talking about the carrier and not the gears?

Anyway: since it's stock, take the VIN and go to your dealer - they can punch it into the computer and give you what they call a "Vehicle Information Summary" (build sheet) - should show the axle ratios installed at the factory.

Common sense, though leans toward the following:

4.0 Engine + Manual Transmission = 3.07 in the diffs
4.0 Engine + Automatic Transmission = 3.55 in the diffs

4-Cyls will probably have deeper gears, but I don't know off the top of my head exactly what.

If memory serves, you can also do the following:

1. Jack up one rear wheel (chock all the others - you'll need the trans in N and the parking brake off for this)

2. Make an index mark on the rear driveshaft (chalk or grease pencil should work for this) and the tire that's off the ground

3. Count the number of revolutions the driveshaft makes for one revolution of the tire. Your count will not be accurate to two decimal places, but will be pretty close.

Personally, I'd hit the dealer first and run the VIN - get the easier option out of the way first.

Rob

Basically what Rob said. By 1994 Chrysler had pretty much standardized the 4-cyl on 4.11 gears, and the 4.0L were all just as he said from 1987 forward. 3.07 with 5-speed, 3.55 with automatic.

Take a drive on a flat highway and note the RPMs at 60 MPH. 3.54 should be somewhere around 2100 to 2200 RPM. 3.07s will be around 1800 to 1900.

Oh, yeah -- it's not 3.93 because that ratio was never offered from the factory.

ok i actually just got back from the dealer, i left before these options were posted, i do have the 3.55, oh that marking the wheel thingy would have been way off(i have 31's not the stock size by a long shot!!) i also called my local 4x4 shop(t-n-t automotive) and got a price quote for putting 4.10's in(gears plus labor for him to do it) this crap is gonna squeeze 1200 bucks outta my pockets( he said considering my milage i should replace all the bearings completely) any way i can get the rins and pinions for like 400 bucks, anyone in the area just love doing this kinda stuff so much thats willing to do this for a 12pack and the company of me on a trail ride when we are done?????

You'd be better off swapping the entire axles from a 4-cyl XJ out of a junk yard.

trashedxj said:

oh that marking the wheel thingy would have been way off(i have 31's not the stock size by a long shot!!)

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Umm....one revolution of the tire is one revolution...tire diameter doesn't really matter. It's kinda like...the earth still takes 365 1/4 days (one year) to revolve once no matter how tall you are. My year is not longer or shorter than yours...even if one of us is sitting at the top of Mt. Everest. See??!!

But you got your answer, anyway. Replacing all the bearings probably IS a really good idea...though it sounds like they're charging kind of a premium for the job.

Complete axles would be cheaper if you can find them with 4:10's. Other alternative is to hunt the forsale forums for a set of gears. Thats how I got mine, just have to put them in eventually.
With complete axles you could pretty much clean em up in your driveway, put new brakes on em and get em ready to go or even do the disc brake conversion while it's out.
The price of $1200 is a tad high but that might just be your area. Figure $800 for the gears and master kit and $400 labor, most places around here in NE PA charge about $150 for gear changes. Before ask, Grand Cherokee's are not swapable w/o alot of work and welding for new spring perches and such.
Just some thoughts...

RichP said:

Complete axles would be cheaper if you can find them with 4:10's. Other alternative is to hunt the forsale forums for a set of gears. Thats how I got mine, just have to put them in eventually.
With complete axles you could pretty much clean em up in your driveway, put new brakes on em and get em ready to go or even do the disc brake conversion while it's out.
The price of $1200 is a tad high but that might just be your area. Figure $800 for the gears and master kit and $400 labor, most places around here in NE PA charge about $150 for gear changes. Before ask, Grand Cherokee's are not swapable w/o alot of work and welding for new spring perches and such.
Just some thoughts...

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I think I am missing something on my estimate then. I figured ~$180 for each set of gears +$65 for each install kit. =~$500. Am I missing carriers in this estimate?

i can get gears from 4wheel parts bopth front rear and the carrier for 459.99 TNT labor to do that + put in bearings would be 600 so 600+460=1060, so i take it bearings are cheap?, and i like the idea of swapping axles for cheaper but i dont have that kinda money on hand now anyway so i guess i be waitin on that job, oh and yes one revolution is one revolution but a bigger tire will throws it off cuz it takes longer to go around thus meaning the DS will rotate a whole lot more in that spare time than before, get it, the only thing i passed in school was math, even tho i slept second semester in 10 and the whole first i was expelled but i still passed that year so i know math, and if im still wrong then i look dumb as hell but what ever!!!! ouch to much thinkin, im going back to bed, later!

trashedxj said:

oh and yes one revolution is one revolution but a bigger tire will throws it off cuz it takes longer to go around thus meaning the DS will rotate a whole lot more in that spare time than before, get it, the only thing i passed in school was math, even tho i slept second semester in 10 and the whole first i was expelled but i still passed that year so i know math, and if im still wrong then i look dumb as hell but what ever!!!! ouch to much thinkin, im going back to bed, later!

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Yeah...I think you need your beauty sleep!!

Tire diameter affects the distance traveled...but not the ratio of tire revolutions to driveshaft revolutions - that's fixed by the gear ratio. So diameter will affect your speed, and the engine speed required to achieve a certain vehicle speed...but everything rotates with respect to everything as an exact function of the gearing. One revolution is one revolution - diameter and circumference have nothing to do with it.

3.55 revolutions of the driveshaft equal 1 revolution of the tires - the gears set that - those gear teeth don't care how big your tires are! All the diameter determines is how far that one revolution takes you...but it's still one revolution...and 3.55 driveshaft revolutions.

Go try it some time when you're not busy sleeping! It'll work...trust me! (I'm not too shabby at math, either - they required quite a bit of it when I studied engineering 15-20 years ago...though this doesn't have a lot to do with mathematical ability.)

I think you're kinda gettin' screwed on the quote, though. Bearings are cheap...and the added labor is not that extensive. And, like you said, you should be able to get the gears for around $400...and other miscellaneous parts for another $200 or so. So they're charging aobut $600 for labor (and/or inflated parts prices) - it shouldn't take them 6 to 8 hours to do this - if labor rates are even THAT high ($80-100/hr.)

TNT...they must be charging you a premium for that high-performance name!!!