[5119]

Gear ratio\'s 31x10.50

I'm a returning jeep (grand) cherokee owner (I've been in withdrawls for 5 years), my last was a '91 limited 3inch lift 31x10.5x15 on 15x8 wagon wheels. I lowered the gear ratio's, but can no longer remember to what. My new rig is a '98 grand with a 4.0 liter. I'm installing the RE 3.5 sure ride lift + 265/70R16 BFG's (about 31x10.5) and I'm going to try the new rubber on the stock rims for now. I'm looking for some advice for a new set of gear's for the axle's. I'd like the ratio's as they sit with the original tires, and would like to stay in the same ball park after the lift/tires.

P.S
I loved my last ride so much my freinds were getting tired of me talking about, so I had to get another (project time).

Thanks for any help

 

[1572]

Re: Gear ratio\'s 31x10.50

i would go 4.10 for 31s, if you plan on going bigger in the future then get some 4.56s

 

[5119]

Re: Gear ratio\'s 31x10.50

I'm check the stealership tomorrow vin/gear ration. My rig has the tow package and may the 3.73's. I do seem to remember that my old rig had 3.55's and warented lower gears with 31's. What if 3.73's are installed? Anyone out there have 31's and 3.73's? I'm sure 4.10 would do better, but I'm iching to know what I should expect when I mount my lift in one week, and my tires 2 days later.

Thanks...

 

[5119]

Re: Gear ratio\'s 31x10.50

P.S

I have a 3/4 ton cummings powered truck for backup (trying not to put any more miles on it except for when I need to pull out the BFG ;-), so I will be driving the he!! out of my grand. From going to work (45 miles away), to the cabin (damn near to canada), 4x outings, etc.. Lockers are my question. My last rig I installed a lock-right in the rear when I lowered the gearing, it was helpfull, but hair raising at times in the MN winters (black ice). This time I think I am going to start with ARB's front and rear (maybe just front at first to save $$) and install the air pump later. Anyone have any pricing for me? Ballpark on the differnce in getting ARB gears vrs. standard open diffs?

Thanks for any help

 

[krabysniper]

Re: Gear ratio\'s 31x10.50

I got the 4.0 in my 90 running 30x9 1/2 so trust me when I say go with 4.11. BTW, have you checked out that ORV park thats right along the interstate on the eastbound side? I live up in Fargo and go to the cities occasionaly thats how I know it's there. Just curious what it's like and if you take your rigs off road?

 

[Guest]

Re: Gear ratio\'s 31x10.50

Find out your stock tire size and ratio, then go to 4lo.com. There's some pretty neat calculators that make everything easy to figure out. Or go to Interco for a chart.

 

[Guest]

Re: Gear ratio\'s 31x10.50

I just completed a 700 mile highway run in mine w/32's and the OEM 3.55 gearset. No probs, great mileage. I'm doing Camp Jeep in Charlottesville, VA where I'll hit a few "foothills" and some trails. I'll be West VA sometime early summer where I'll hit a few higher "foothills" and some more trails. I may rethink my position after those runs but for now- I'm keepin' the gears the way they are. It's not a blazin speedster off of the line- but then again it never was.

 

[5119]

Re: Gear ratio\'s 31x10.50

I do take my rigs off-road, but I have been without a jeep for 4+ years. I used to run in some of the mud runs around town, and the family cabin up north is at the end of a 1 mile logging road after a 12miles low maintenence road. It used to get really interesting during heavy rains and snow storms. Much 4x4'n. Now that I know the ORV park is there I'll check it out and let ya know. What town is it in?

 

[krabysniper]

Re: Gear ratio\'s 31x10.50

I don't remember exactly where but I am thinking it is right around your area or maybe more by Rogers, I always see it going there after the exit you need to take to get to it.

 

[Guest]

Re: Gear ratio\'s 31x10.50

Unless you like to spend money, stick with what you have. The 31" isn't that far a departure from the 29" that was stock and especially with the automatic you won't have as much of a problem because of the torque converter windup on startup. Take it and run with it!

 

[1284]

Re: Gear ratio\'s 31x10.50

I wouldn't change them at all if your only going to 31" tires. You'll get better gas milage if you don't change them and its not big enough of a tire to have any real power loss.
-Beastmaster

 

[Guest]

Re: Gear ratio\'s 31x10.50

Yup plus it's not exactly cheap. I've gotten quotes of $500 for labor alone (for the two diffs). Toss in another $300-600 for the gear sets and if your talkin lockers another $600-1000. All that and you still have a 35, 35C or an 8.25 rear diff with drum brakes pushing 31's.
Not that there's anything wrong with that.....
Like I said in my earlier post the power "loss" is minimal and other than that I've noticed the tranny will "hunt" a little more than before.

 

[Guest]

Re: Gear ratio\'s 31x10.50

Ya, I am running 31's with the stock 3.55's, and mine seems fine. My buddy drove it while his '84 2.8 was inthe shop and he told me mine was way fast, haha. Sometimes on hills I wish I had the 4.10's, but then again, it's not that hard to put it in low range and have pleanty of power. Around town it is fine, and I don't notice much of a difference between my 225's and my 31's. If you go ahead and stay with stock gears, some lilttle things like good exhaust, an airtube, and maybe a TB spacer will bring you right back up to or above where yopu were with stock tires and gears.