Regearing 32's??

Will I have to regear if I run 32's? I have D30/35, auto tranny and NP242 t-case, if that matters. If I do then what gears would you recommend?

Thanks!

you don't HAVE to re-gear, I reccomend it though. 4.10 feels really good at that diamaeter. tell us your stock gearing and we'll tell you how far off your speedo will be. drive it before you re-gear, and feel the sluggishness, also know that your speedo will be reading somewhere on the order of 12% slower than your actual speed if you do not re-gear

i'd run 4.56's. i have 4.56's and 31's and its nice, w/33's i think it will be a tad undergeared and perfect with 32's

goodburbon said:

you don't HAVE to re-gear, I reccomend it though. 4.10 feels really good at that diamaeter. tell us your stock gearing and we'll tell you how far off your speedo will be. drive it before you re-gear, and feel the sluggishness, also know that your speedo will be reading somewhere on the order of 12% slower than your actual speed if you do not re-gear

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Would this kill my gas milage or be bad for the engine to run on the highway?Also couldn't I get a speedo gear to correct the speedometer?

TDeaton13 said:

Would this kill my gas milage or be bad for the engine to run on the highway?Also couldn't I get a speedo gear to correct the speedometer?

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your asking if you dont reagear? then the answers are yes yes and yes. moreso the tranny than the engine, but it will make it harder on everything.

Go directly to 4.56, skip the 4.10

BlueGerbil said:

Go directly to 4.56, skip the 4.10

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exactly.

4.56.

no question.

What type of mpg and rpm will I get with 4.56 gears just crusin' down the highway? This is my DD and need to be ecomomical.

You'll be more economical at 32s and 4.56 than with 4.10s or 3.55s...but a lifted Jeep running 32s isn't exactly "economical" - I'm getting 16-17 (sometimes 18+)mpg with mine, corrected speedometer, etc. That's about 2mpg better than I was getting with 32s and 3.55s

I have 4.88s and 33s (for street driving) with an auto tranny. It is perfect, good power at all speeds, and if I drive at a nice constant 70mph I can get 20mpg. That said, with 32s I would recommend 4.56 gears, or 4.88s if you think you may go bigger than 32s in the future. Another consideration is axle strength, a D35 with 32s and a locker is a BAD idea, so if you think you'll ever lock this axle, it may be a good idea to swap something stronger and regear that now.

Thanks for the info guys! So do you think I could find any 4.56 that fit my Jeep in a boneyard or would I have to buy them from a shop??


Thanks

I am running 4.88's and 33's on my daily driver, I get 17+ mpg highway depending on the style of driving I decide for that day. With that said I would recommend the 4.56's on 32's or 4.88's if you plan on going bigger..

I'll take a shot here as the odd man out.

I daily drove my XJ for a little over 100k miles over the last 4 years before parking it as a trail only rig about 6 months ago.

Most of that was with 32" BFG MT's and 3.55's with a 4.0 and AW4. It was certainly not the quickest thing I ever drove but I consistently got 20 mpg or better on my 104 mile daily commute. I also didn't carry every piece of recovery gear I own nor did I have a roof rack or anything else but the stock rig on 4 inches of lift. I ran my tires at 40 psi. 60 mph was around 1800 rpm.

I switched to 4.10's about 6-8 months before parking it and it definitely helped but the fuel economy suffered a little as the 60 mph rpm was now about 2150 or so.

Only go bigger numbers on the gears if you plan to go bigger on the tires later. For me, I swapped in some 4.10 axles out of 2.5 liter rig and the whole swap cost less than the install kit for one set of gears would have been. The D30/D35 combo (front has 297 joints in a non-disco axle) handles 32's well. I've never broken anything having done the Rubicon twice and every trail here in Washington.

My opinion is that you shouldn't carry all your gear with you every day, take off your rack if you have one and keep your foot off the gas pedal as much as you can. You'll have decent mileage, decent off-road gearing and a very DD-friendly rig.

i ran 31's and 3.55's and would never get close to what you had, more often than not it was closer to half that.

I agree with JohnXJ for anyone on a budget. I too got my 4.10 differentials from a boneyard because of some fo the prices I got for regearing. I'm running 31's and its a perfect match between metal and rubber and the road. Please also know that in my case regearing was a necessity due to the fact that I had a 5 speed which came stock with 3.09's. Also please know that swapping out axles is not a job for the faint hearted. Not to discourage you, but it is a huge job without a hydraulic lift. In my case it took 4 people an entire weekend to install the diffs plus a lift kit. Good luck, J

if you are on a tight budget then do the axle swap. if not go 4.56's and dont look back

If you plan on going bigger than 32s sure go 4.56, but I ran 4.10 with 31's and the power was there, I am currently using 4.10 with 33s, no problems, the speedo is right on the money, the power is right on, and its a daily driver. I don't know about good mileage from 4.56 with 32's just seems too steep for the highway. My mileage dropped to 14.5 when I first swapped from 3.55 to 4.10 and kept my 31's, (with the corrections for actual mileage made) If I had not corrected the mileage it seemed that I was getting better mileage.(it also seemed that I was going 10% faster than I actually was.)

you can go 4.56 and you will have all of the low end torque in the world, but the highway will require you to rev too high in my opinion. Thats just me, and everyone has different experience to draw from.

I have 4.56s with BFG AT 31s. If I drive 65 or less on the FWY, gas mileage will run 18-20 MPG. If I drive any faster than that, it will slip to 14-16. I have found that I don't like running any faster than posted speed limits anymore anyway due to the engine noise above about 2700 RPM.