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Old January 11th, 2020, 11:23
BenTheMan21 BenTheMan21 is offline
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Differential gearing?

I have a 2000 jeep cherokee sport. Nothing too crazy about it. A 4.5 inch lift sitting on 33s with stock axle, transmission, and differential. I dont plan to do any crazy crawling but mostly a daily driver and a little bit of light offroading every now and then. It feels pretty sluggish when i start moving, i have to give it a lot of gas to get moving. I figure this is normal with those oversized tires but i hust need any recommendations of any way to fix that. I dont need to ever go over 80 mph so im not worried about speed too much. But im pretty new to modifying my jeep and wasnt sure what parts to swap out to help this. Any help or comments appriciated. Thank you.
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Old January 11th, 2020, 11:54
RCP Phx RCP Phx is offline
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Re: Differential gearing?

4.56's for off-roading and 4.10's for street use.
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Old January 11th, 2020, 12:52
Wayne Sihler's Avatar
Wayne Sihler Wayne Sihler is offline
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Re: Differential gearing?

Originally Posted by RCP Phx View Post
4.56's for off-roading and 4.10's for street use.
Like he says.

Ive been running 4:10s for years, lots of highway miles.BUT I wish I would have gone with 4.56s now that its not my daily driver.
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96XJ,4.0,AW4,D30/D44,4:10s,Detroit,4.5" lift 33,s
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Old January 11th, 2020, 13:26
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smokeyyank smokeyyank is offline
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Re: Differential gearing? is a good place to start.

I'd suggest 4.56s. I ran 4.10s and they where good for daily but when it came to getting up the hill or off road it left something to be desired.
88 MJ truggy, 4.0HOybrid AX15, NP242 **Being built**
Mods: D44 w/ 4.30's, ARB front and Auburn rear, 33's
04 WJ, 4.7HO
Mods; 3" IRO lift, ADDCO rear sway bar, 4.7HO with bored fastman TB, AFE intake and Superchip tuner, 32s, lunchbox rear 242HD, 3" Kolak exhaust
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Old January 11th, 2020, 14:26
Black1990jeep Black1990jeep is offline
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Re: Differential gearing?

I have 33 tires, and 4.1 differential gears.
Bought the XJ for offroad camping, and some rocking, but that offroading may require 400 to 1000 miles highway driving just to do 50 to 200 miles of off roading. prior owner put in 4.1 gears when he had 31 inch tires, but later put on 33 inch tires.

I do have a very low range transfer case, at 4.1 in low (Atlas 2) so off roading in Low transfer case with 4.1 differentials is still pretty nice because of the transfer case low range gear being a lot lower than a stock transfer case.

On highway, on the flats, it cruises ok, but does need to down shift on hills, even moderate hills to maintain a decent speed. I travel with a fellow Cherokee friend, he has my same differential gearing on smaller 31 inch Tires. He can out pace me on the highway hills.

he also has the later 2001 H.O. motor, where as I have the weaker 1990 Renix motor.

On moderate grades I am usually a gear lower than him ie he may still be in 4th, while my tranny (AW 4 Auto) is in 3rd, so ineffect my rpms are higher on hills, of course on the flats, or with a stiff tailwind, both our Xjs at 70 mph In fourth gear, my rpms are lower than his, but he is oft better in the power band for passing.

Now with a stock transfer case gearing, I have not driven one with 33 tires and 4.1 differentials much less one using low 4wd, but I would heed the info by others, your crawling ability may be reduced, Low 4 in first gear will not be so low with that 4.1 differential and a stock transfer case, and if you rock crawl, or do mega steep offroad, you probably will notice a difference, but with an automatic tranny, you do have a bit of leeway, as the torque converter can slip more to a point to make up for gearing. using torque converter slip to get that lower in effect gearing does heat up the ATF fluid in the tranny, so dont try that all day long on a long steep crawling type road, but for a short section, with a good tranny cooler set up, you can do this without harming the tranny. If you have a manual tranny, forget it, clutch slipping is not a viable option!

So yeah, 4.1 differential gearing is kind of fine on long relatively flat high speed highways, with little need for passing acceleration. but you do end up in 3rd or even 2nd on some highways on grades.
The later bigger power engines probably are less effected than early motored XJs

Your driving style too is a factor on highway, if youre an aggressive, get there fast type, the 4.1 is not as nice, if you dont mind slowing a bit up hill, but making it up on the down hill, and dont try to be the fastest vehicle on the road and pass others, then the 4.1 is fine on the highway

My old ride was a VW Vanagon, flat four maybe 95 to 100 Hp, (I upped displacement from 2.1 to 2.2 liter), and we took it on many a road trips, mountain camping etc.. It was slow, it is a different driving mindset, and I enjoyed it despite being passed by loaded semitrucks on highway 80 in the California Sierra, climbing neary10,000 feet.
My 33 inch tired, 4.1 differential geared, early Renix motored XJ is slow, but not near as slow as that old VW Vanagon.
Now I could tell you about how slow my 63 VW Split Window Microbus fitted with a 1961 1200cc Bug motor was when going into the high Sierra for back packing back in my youthful school days. How slow? That was get out and walk speed on some grades, Literally! and the worn tranny would pop out of first under load, so I had to keep one hand on the stick shift to hold it in gear up highway 80 heading towards Donner, or highway 120 over Tioga Pass. that 1200cc motor was rated as 40 Hp, but it was tired, and at 9000 feet was probably only producing half that 40 Hp!

Anyway, that is my two cents.

Now if you habe a stock
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Old January 11th, 2020, 15:40
BenTheMan21 BenTheMan21 is offline
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Re: Differential gearing?

With me driving mostly highway it sounds like 4.1 is the way to go. When i say light off roading i mean really light. I havent done much looking into new gears but is there one brand thats better than the other? Id like to stay on my stock axles. Thank you guys for all thr pointers and replies. I appriciate all the input.
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Old January 12th, 2020, 06:23
89Mock 89Mock is offline
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Re: Differential gearing?

After looking into it I don’t think you gain as much as people say with 4.56 on a stock transfer case. I think I’m going to regret going to 4.56 just because I drive mine on the highway a lot and I’m still leaning towards 4.10s based on a friend who has about 30 years of wheeling experience.
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Old January 13th, 2020, 00:43
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lazyxj lazyxj is offline
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Re: Differential gearing?

My 2001 has 4.10 for several years, running 31"s. When upsizing to 33"s, it remained on the 4.10s for a couple of months before gearing it to 4.56s.
The transmission downshifted anytime a slight hill came up and it felt sluggish.
After the 4.56s were installed, I tried the 31's again and it was blast to drive, with the 33"s, it cruises at a similar RPM that it did when stock.
When considering how much more energy is needed to push the extra weight, the 4.56s work better and the mileage is slightly better with the 4.56s..if I can keep my foot out of it.
Through the years on the forum, many have regretted not getting deeper gears, few complain of having gears that are too low.
Both XJs are still Real XJs
01 Sport, Russ Pottenger 4.6, AW4, 4" lift, 33 X 10.50 KM2, 4.56-8.25 TruTrac, D-30-E-Locker with alloy shafts, Hidden M8000 winch, Vanco front and ZJ rear disc brakes, Frame stiffeners, Lots of armor, Towing baseplate.
1997 Country, Mostly stock, 2" lift, Engine mods, NP242, Towing baseplate
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Old January 13th, 2020, 09:27
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cal cal is offline
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Re: Differential gearing?

Even with my giant stroker 4.10 is not enough for 33's. Will rehear 4.56 sometime this year ish.
I'm not a complete idiot - there are parts missing.
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Old January 14th, 2020, 10:52
Car Enthusiast Car Enthusiast is offline
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Re: Differential gearing?

I went 4.88s on my 01 and it does awesome it seems like everywhere. Still will do 100mph
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Old January 14th, 2020, 13:05
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Re: Differential gearing?

The more you build your rig, the more you need to consider all of the variables which directly impact the calculation of the correct gear ratio, that will net you the best balance of power/fuel economy and how you use your rig.

Many fail to consider the added weight of body armor, larger tires/wheels/full size spare, wider contact patch/rolling resistance of said tires, added wind resistance from lift, larger tires, lights, roof rack/cargo, age of engine/power loss, pulling a trailer, get the point.

The elevation where your rig operates is also a variable that many fail to consider when doing a gear swap. All HP/TQ numbers are calculated at sea level and the more altitude you gain, the lower the oxygen ratio, therefore, the less power the engine will output.

In the past 15 years, I've run 4:56's and 4:88's in two different XJ's, both with 33's and 34's (ish, 295/75/16) and have never regretted the jump to 4:88's. My normal operating elevation is approx 4800ft above sea level, with local trails that approach 10k ft elevation, so 4:88 gears are perfect for how I use my rig.

My Jeep now only sees about 3-4k miles a year, but I used to daily drive it and logged over 100k miles on 33's and 4:88's, averaging 16-17mpg.

At 220k miles on the clock, the engine is feeling a bit tired, but with the 4:88's, it still has no problem moving the Jeep down the highway and getting up to speed without hesitation.

I have a stroker build underway using a replacement engine and will continue to run 4:88's with the stroker, as they work for well for how my rig is built, my operational elevation and how I regularly use my rig.

Your mileage may vary.......
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