456 vs 488 Questions

[grimmjeeper]

Not axle. Gears.

They're either shitty gears, shitty installs, or I'm a really, really shitty rock crawler. Take your pick.

Could be more than one is true...

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[Ratbert]

Could be more than one is true...

Not that I've become paranoid about possibly damaging them, but...

 

[grimmjeeper]

Not that I've become paranoid about possibly damaging them, but...

Yeah, I do things like this...

 

[Ratbert]

Yeah, I do things like this...

Man, that looks pretty damn challenging, even on video where it's just about impossible to convey just how difficult it is.

 

[grimmjeeper]

Man, that looks pretty damn challenging, even on video where it's just about impossible to convey just how difficult it is.

It's challenging. But it's only a 7 rated trail. I'm on 37s now so not as hard. But I don't want to tear my JL up too much. So I'm working on building a Comanche truggy on 43s so I can have fun on the trails I really want to run.

 

[Old Jeeper]

Not axle. Gears.

They're either shitty gears, shitty installs, or I'm a really, really shitty rock crawler. Take your pick.

I don't think it because you are not a good rock crawler or a poor installer of gears, so it must be the gears...

 

[J0E]

You never cease to amaze me.
3 pages of decent discussion and you showed up, first thing you did was to attack others. And brought up whole bunch of nonsense to try to build up your "credential". All those moves tell me you are extremely insecure because no one gave a crap about the points you try to make.
"The loudest one in the room is the weakest one in the room."

Your website is shit by the way.

first thing you did was to attack others.

What was nonsense? You can't articulate any problems with my post. All you've got is ad hominem attacks. No facts, just attacks. My web site is crap? How so. Let's see you write a better one.
Meet mee at Sand Hollow or Moab and we'll see who's right.

 

[JamesWyatt]

...If you want to optimize for the highway, I'd say skip it and put the money somewhere else...

If Jeep offered a v6 turbo or continued selling the 3.0L diesel for 2024, I might agree.

Regarding cost, I paid ~16% off MSRP for my 2024, which means the $995 4:88s gears only cost me $840 – factory installed and under warranty.

 

[c20040215]

What was nonsense? You can't articulate any problems with my post. All you've got is ad hominem attacks. No facts, just attacks. My web site is crap? How so. Let's see you write a better one.
Meet mee at Sand Hollow or Moab and we'll see who's right.

The last time I heard someone said "meet me at xxx and see what happens" was from a 12 year old. You can do better than that.

There is no fact. Just you and your personal belief that 99% of the people do not agree with. People here laughing at your posts for a reason.

Where did you get your facts?
www.iamright.com?

 

[Gorilla57]

The last time I heard someone said "meet me at xxx and see what happens" was from a 12 year old. You can do better than that.

There is no fact. Just you and your personal belief that 99% of the people do not agree with. People here laughing at your posts for a reason.

Where did you get your facts?
www.iamright.com?

I was just in Sand Hollow......maybe I should have called out JOE......

 

[Jtphoto]

Looking at a Rubicon X Unlimited with 8 spd auto. Not planning to run bigger than 35” tires but it comes with 488 gears prefer 456 which is what I have in my 84 CJ7 with LS1. Is it worth the extra bucks or should I keep looking? Think it’ll affect mileage much? If I hate it can I regear to 456 by changing ring and pinion or does it require a carrier change as well?

I have 4.56 in my Xtreme Recon. On 35s it was perfect. It would stay in 8th on the highway no problem. Moved up to a light 37 and it has affected how much it stays in 8th. I’d suggest 4.88 with 37s, 4.56 for 35s.

 

[DubaiMarauder]

same setup here, love the 4.88 with 35s. 4-low locked into first gear the thing would walk up a wall

and it’ll do 80+ down the highway all day

at what RPM? 3500?

 

[c20040215]

I was just in Sand Hollow......maybe I should have called out JOE......

No. I would not. He would call you out for running the wrong gear ratio. Hows the cell reception there? He might even pull out his webpage to prove it.

What rig were you running? If it's not a stretched LJR on 43s sticky, it's trash.

 

[DubaiMarauder]

I have 4.56 in my Xtreme Recon. On 35s it was perfect. It would stay in 8th on the highway no problem. Moved up to a light 37 and it has affected how much it stays in 8th. I’d suggest 4.88 with 37s, 4.56 for 35s.

Looking at a Rubicon X Unlimited with 8 spd auto. Not planning to run bigger than 35” tires but it comes with 488 gears prefer 456 which is what I have in my 84 CJ7 with LS1. Is it worth the extra bucks or should I keep looking? Think it’ll affect mileage much? If I hate it can I regear to 456 by changing ring and pinion or does it require a carrier change as well?

The issue is gears are tied to tire size and rpms, sorta. There is a relation to how one affects the others. The issue with jumping to 4.88s is RPM and fuel economy. Unless you don't care about getting 12mpg, you should consider keeping things balanced. 33's work fine with 3.73 gears in the diesel, but for most gassers, Jeep upgrades the gears to 4.10's due to lower torque.

In the 2024's with the XR package, Jeep gives you 35's and 4.56 gears, which is a nice balance, with a slight mechanical advantage to the motor while keeping RPMs down just a tad over the 4.10 gearing previously offered. If you go to 4.88's on 35's, your fuel economy is going to drop another 2mpg approximately. It will balance out if you throw 37's on, but the fuel econ you would have saved, you're going to lose due to the rotating mass of 37's.

On the bright side, if you go with 4.88's pushing 35's, you'll probably be able to do burnouts at every stoplight.

A good formula for calculating next gear size up (if needed) is:

(New tire size x old gear ratio) / Old tire size

For my JLURD with 3.73's and 33's, that equation looks like:

(35" x 3.73) / 33" = 3.95 (new gear ratio needed)

Considering that there are no 3.95 gears (without custom ordering them), the next size up would be 4.10 gearing. So, my next step up over my current 3.73's would be 4.10's to support me running 35's which isn't really that necessary but would give a bit of a mechanical advantage to the motor.

In your case, Jeep gives you 35's and 4.56 because they've already determined that is what is good enough. Unless you plan on doing some serious rock crawling and adding 37's, I'd stay right where youre at.

 

[MA Joop]

at what RPM? 3500?

I don’t think it’s that high at 80 but honestly I’d have to see. Theres a spreadsheet somewhere on the forums that does easy calcs for rpm at various speeds by inputting gear ratio and tire size, but I can’t locate it at the moment.

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