4.88 and 33" tires

[cal]

arctycfox: You're right, 4.10 are damn close to stock.
Hell, the Rubicons roll out with 4.10s and 32"s.

The rubicon's that come with 4.10's and 32's also come with a v6 minivan motor that spins up to 4 grand before it shifts, 5500+ passing. Its not uncommon to see one downshift to 2nd on the freeway.


I've been running 4.88 with 35's for a couple of years, and anytime I have to do a lot of highway driving find myself wishing I had 5.13's or 33's.

 

[WaXJ_Skier]

what would you recomend for a 99 5spd xj DD im going 4.10s 33's will that be bad?? im doing 4.10s because i can do it for 450.00 total....

save your money and do 4.56 or 4.88s for $1000 you can get gears and lockers for front and rear. Find somebody that will do the install cheap and you are set

 

[garr]

The rubicon's that come with 4.10's and 32's also come with a v6 minivan motor that spins up to 4 grand before it shifts, 5500+ passing. Its not uncommon to see one downshift to 2nd on the freeway.


I've been running 4.88 with 35's for a couple of years, and anytime I have to do a lot of highway driving find myself wishing I had 5.13's or 33's.

Your right, I don't like the way the new Rubi feels, It should have stuck with 31s or geared up to 4.56!
I also think the Rubi (Exspecially the 4door) weighs a bit more than an XJ,
Just curious, What is the Rubis Horsepower/Torque & Weight?

 

[cal]

what would you recomend for a 99 5spd xj DD im going 4.10s 33's will that be bad?? im doing 4.10s because i can do it for 450.00 total....

What you save up front, you will lose in gas in the long run. The 4.0 would rather spin a little fast than work a little hard.

Do it right the first time.

 

[cal]

Your right, I don't like the way the new Rubi feels, It should have stuck with 31s or geared up to 4.56!
I also think the Rubi (Exspecially the 4door) weighs a bit more than an XJ,
Just curious, What is the Rubis Horsepower/Torque & Weight?

I don't know. My father drives one with a 3" lift, stock gears/axles/tires. We towed 4500 pounds up over the mountains with it last week though, like the weight wasnt behind us.

Its got the power, just at higher RPM's than the 4.0 we are used to. Once you put it in 4-low, it really doesn't matter anymore. Different, but not deficient.

 

[Blazair]

I've been running 4.88 with 35's ..., and anytime I have to do a lot of highway driving find myself wishing I had 5.13's or 33's.

X2

 

[Mike1331]

I've always been weary of putting 4.88's in the d30 because of the horror stories I’ve heard of breakage. With the ring gear of the 4.88 being the tallest you can fit in the 30 doesn't that create excessive strain on the housing and carrier? Anybody run 4.88's with a turdy at high speeds in the sand and dirt with no problems? Top speed in the dirt with 33's and 4.56’s would probably only be around 75 though with the power plant of the 4.0 and the aw4.

 

[cal]

I've always been weary of putting 4.88's in the d30 because of the horror stories I’ve heard of breakage. With the ring gear of the 4.88 being the tallest you can fit in the 30 doesn't that create excessive strain on the housing and carrier? Anybody run 4.88's with a turdy at high speeds in the sand and dirt with no problems? Top speed in the dirt with 33's and 4.56’s would probably only be around 75 though with the power plant of the 4.0 and the aw4.

Before I built my 30 (which is retardedly polished), I researched that. I found as many if not more broken 4.56 gears than I did 4.88's.

 

[Mike1331]

That’s bizarre, because the ring gear of the 4.88 is taller than the 4.56 so physics would allow one to create more strain on the components than the other. If your right and 4.56 breakages happens more so than 4.88 then it looks like I’ll be buying my third set of gears. At least I haven’t installed any of them yet.

 

[cal]

Its just what I saw reading through a few hundred posts here. In theory the 4.56 should be stronger, it just doesnt seem to make that much difference in practice.

 

[redkling]

http://4lo.com/calc/geartable.htmhttp://img230.imageshack.us/my.php?image=gearcalcba6.jpg

 

[cal]

That calculator holds no accuracy for us. It is calculated assuming a 1:1 final drive ratio, where we have an overdrive.

 

[juniorXJ]

what about 4th on an ax15. that should be near 1:1

 

[cal]

yes, so is third on an aw4 ..

but unless you plan on driving around in third or fourth gear for the rest of your life, why bother gearing based on that?

 

[juniorXJ]

thats exactly what im doing now with 235s. thats kinda funny. i was just curious.

 

[arctycfox]

yeah but aren't ax-15 equipped XJ's running 3.09's stock? by my math that means with 35's 4.005 is where I should be for stock. so going to 4.10's would already be going deeper. Wouldn't 4.56's or lower really bog me on the highway?

 

[WaXJ_Skier]

yeah but aren't ax-15 equipped XJ's running 3.09's stock? by my math that means with 35's 4.005 is where I should be for stock. so going to 4.10's would already be going deeper. Wouldn't 4.56's or lower really bog me on the highway?

ax15 is 3.07s stock so 4.10 is about the same rotation wise for 35s...but that doesn't take into acount that larger tires(and life and armor and bigger axles) adds weight into the equation. 4.56 or 4.88 is where you want to be. I get better gas milage with the 4.88s than I did with 4.10s.

 

[garr]

I don't know. My father drives one with a 3" lift, stock gears/axles/tires. We towed 4500 pounds up over the mountains with it last week though, like the weight wasnt behind us.

Its got the power, just at higher RPM's than the 4.0 we are used to. Once you put it in 4-low, it really doesn't matter anymore. Different, but not deficient.

I just checked the 4 door Rubi specs, Curb weight 4500lbs, Engine HP 203, 4.10 gear ratio.
No wonder I thought it felt sluggish when i drove it, it weighs 1500 more pounds than an XJ & only has 10 more HP.

 

[kj139]

I'm with WaXJ Skier. I have 35's with 4.56's and I am ordering 4.88's so I can install them next week. I went with 4.56's, as there are 3 teeth in contact vs. 2 with the 4.88's Not a day goes by that I don't wish I was on 5.13's. Since I can't get those for the D-30, 4.88's it will be.

I have installed lots of gears on lots of friends' Jeeps and I ALWAYS tell them to gear at least one step more than they are planning. Each of them says the same thing..."My gas mileage will suffer." In reality, gas mileage will suffer (along with other things) because the Jeep has to lug to get off the line. So around town or anywhere there is a hill, the Jeep becomes a dog. I went from 17 MPG to 10 MPG, partially because of the gearing, but also because the gearing was throwing off the transmission shift points. I run 80MPH on the freeway (from time to time :nono: ), and I would have absolutely no problem with installing 5.13's if I could get them. I was all excited when I saw that the new JK axles have R&P in 5.13's available but then found that they wouldn't work.

In fact, I just installed gears and lockers on my boss' Jeep and he would only let me increase it from 3.07 to 3.55 with 31" tires. I did another friend's the same weekend, but he chose 4.10's. Huge difference.

Good luck!

 

[yamafreek]

Im going to run 4.56 with 31"s on my 99 xj. On my 03 TJ I had 4.56 with 33"s and could have used more gear trans would hunt in and out of od up small hills. I think the lock up AW4 has a .67-.75 OD.