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JeepersCreep3rs 04-15-2013 10:20 PM

Help gearing!!
 
I have 33x10.5 Terra Grapplers and my front diff says i have a 3.07(I have an 02 wrangler x, 5-speed). I get about 12-13 mpg and if im towing i get like 9-10. What gears should i go to? Keep in mind it has about 136,000 on it. Would it be better to do a whole axle swap with lockers or just do the gearing? What would be needed?

P.s- when on the interstate if i shift out of 4th I just slow down and dont stay at a constant speed so usually stay at 70mph(stock settings) in 4th.:hide:

JeepersCreep3rs 04-15-2013 10:21 PM

Also if an axle swap whats the better company to go with?

JeepersCreep3rs 04-15-2013 10:24 PM

myjeeptj.com Blog Archive Gear ratio to tire size chart

Jerry Bransford 04-15-2013 10:26 PM

It'd be a lot more cost effective to just regear both axles to 4.56 than to replace the axles. Typical costs to regear a pair of axles including all parts & labor would be somewhere close to $1300-1400. I dickered & got my last regearing done for <$1200. 4.56 would be ideal for the 33" tire, 5-speed, and 4.0L engine combination.

thgr8alex 04-15-2013 10:33 PM

How drastically does this change mpg? I have 33s with 3.73 gearing and get 14-16 mpg city. Not bad but i cant go above about 60 or 65. I guess thats really all it would change is top speed? Maybe hwy mpg?

Jerry Bransford 04-15-2013 11:59 PM

3.73 is an inefficient ratio for 33" tires, the engine will often lug at the lower RPMs you'll get with larger diameter tires like that when driving at a particular speed like 65 mph. Which is why with bigger diameter tires, we go to lower axle ratios to raise the engine RPMs back up to where they should be... in the engine's more efficient power band. And in ratio-speak, 4.56 is a lower ratio than 3.73 is.

So that just means that lower RPMs don't necessarily mean better MPG and higher RPMs don't necessarily mean worse MPG. For 33" tires, I wouldn't expect your mpg to decrease by regearing from 3.73 to 4.56. It might even improve slightly because the engine will be running more efficiently which can mean better mpg. Which is why all cars & Jeeps don't come with crazy high axle ratios like 3.07 to produce the lowest possible RPMs. Where the best possible mpg is concerned, too low of an RPM is just as bad as too high of an RPM. Whatever ratio allows the engine to run most efficiently will produce the best possible MPG. :)

JeepersCreep3rs 04-16-2013 06:12 AM

I've been told locally to go to 4.11s for better mpg, and if I want 35x12.5s in the future. Is this true? What else could I do for better mpg, while maintaining off road abilities.

Jerry Bransford 04-16-2013 09:24 AM

Quote:

Originally Posted by JeepersCreep3rs (Post 3642887)
I've been told locally to go to 4.11s for better mpg, and if I want 35x12.5s in the future. Is this true? What else could I do for better mpg, while maintaining off road abilities.

4.11 seems to be the favorite of all the V8 driving kids who man the parts counters who base their recommendations on what their buddies tell them is the cool way to go... 4.11 just has that coolness associated with it right? Even some mechanics always push 4.11 but they are often just grown up versions of those kids who don't really have experience with anything but their own jacked up V8 equipped trucks... which require different ratios and are less fussy about the ratios they run well with.

The problem is that for 33" tires, it's not enough gear & the engine won't be operating efficiently which is why I took some extra time above to go into that. 4.56 is the correct/most efficient ratio for 33" tires and 4.88 is the correct/most efficient ratio for 35" tires... 4.11 wouldn't be the right choice for either size tire with your 4.0L engine and 5-speed transmission. Could 4.11 be used? Of course but it wouldn't be as good of a choice.

sinbob 04-16-2013 09:38 AM

Quote:

Originally Posted by Jerry Bransford (Post 3643383)
4.11 seems to be the favorite of all the V8 driving kids who man the parts counters who base their recommendations on what their buddies tell them is the cool way to go... 4.11 just has that coolness associated with it right?

The problem is that for 33" tires, it's not enough gear & the engine won't be operating efficiently which is why I took some extra time above to go into that. 4.56 is the correct/most efficient ratio for 33" tires and 4.88 is the correct/most efficient ratio for 35" tires... 4.11 wouldn't be the right choice for either size tire with your 4.0L engine and 5-speed transmission. Could 4.11 be used? Of course but it wouldn't be as good of a choice.

x2 I have 4.88's on 35's with the 4.0. I get 15 to 16 mpg. One other thing Jerry did not tell you is that if you do not have dana 44's I believe you will have to upgrade your axels in order to run 35's safely. I do not know what you have for axels, but I assume you have a dana 30 frt and a dana 35 rear. They will run 33's safely. I believe that the 30 is actually stronger than the 35 and may be able to accomadate 35's.
Jerry knows more about this than me, so what say you Jerry??????

Jerry Bransford 04-16-2013 11:28 AM

It's not that the front Dana 30 is technically stronger than the rear Dana 35 is, it's that the front axle seldom sees more than about 50% of the stress/load that the rear axle sees on a regular basis.

JeepersCreep3rs 04-16-2013 11:42 AM

It's the stock axle that comes on the X, which also has the stock 3.07. Should I go after a local shops offer that has a used rubicon driveline for 3k?

Jerry Bransford 04-16-2013 11:51 AM

I wouldn't spend $3K to get Rubicon axles just to run 33" tires. I'd just upgrade your rear axle with stronger alloy axle shafts like from G2 & regear to 4.56.

JeepersCreep3rs 04-16-2013 01:09 PM

Well in the future I'm looking to get 35x12.5s. They are also the stock axles from 2002 and don't look that nice. I will take some pics in a bit to let you see what they look like.

JeepersCreep3rs 04-16-2013 01:11 PM

The next time I get tires I want to get 35x12.5s so it's in the near future.

Jerry Bransford 04-16-2013 01:51 PM

Quote:

Originally Posted by JeepersCreep3rs (Post 3644156)
Well in the future I'm looking to get 35x12.5s. They are also the stock axles from 2002 and don't look that nice. I will take some pics in a bit to let you see what they look like.

What axles are you talking about? If you are still talking about the Rubicon axles, they didn't come out until 2003.

lovemachine 04-16-2013 02:36 PM

Quote:

Originally Posted by Jerry Bransford (Post 3643886)
I wouldn't spend $3K to get Rubicon axles just to run 33" tires. I'd just upgrade your rear axle with stronger alloy axle shafts like from G2 & regear to 4.56.

I'm a bit confused.

I have a '05 Sport auto, with a D35, stock gears, running 33's.

Instead of buying a D44 axle with lockers, you mean I can just get this: G2 Axle and Gear Part 96-2033-1-30 - Dana 44 Rear Axle Kit , and then regear, and be G2G with 35's?

Jerry Bransford 04-16-2013 02:54 PM

Quote:

Originally Posted by lovemachine (Post 3644422)
I'm a bit confused.

I have a '05 Sport auto, with a D35, stock gears, running 33's.

Instead of buying a D44 axle with lockers, you mean I can just get this: G2 Axle and Gear Part 96-2033-1-30 - Dana 44 Rear Axle Kit , and then regear, and be G2G with 35's?

No, that kit only works if you already have a Dana 44 axle so it wouldn't work with your Dana 35.

What you need is a stronger axle shaft kit designed for your rear Dana 35. They are available in hardened 27 spline alloy shafts that are roughly equivilent in strength to a Dana 44's OE carbon steel 30 spline shafts. Or a Super 35 kit which replaces the carrier with a full case locker and upgrades the shafts from 27 to 30 spline alloy shafts that are stronger than the Dana 44's OE carbon steel 30 spline shafts.

There are a few manufacturers out there but since Superior Axle's recent near total shutdown, that leaves manufacturers like Ten Factory and Alloy USA to fill in the gaps. G2 is one of the later manufacturers to enter the axle shaft marketplace but I am not aware of a Dana 35 axle product from them yet.

lovemachine 04-16-2013 02:57 PM

Oh!

Well, I'm retarded then. I should have known that....

"Sigh", I'll just have to continue to save up some cash then.

SpoiledRotten 04-16-2013 02:57 PM

Quote:

Originally Posted by Jerry Bransford (Post 3641882)
It'd be a lot more cost effective to just regear both axles to 4.56 than to replace the axles. Typical costs to regear a pair of axles including all parts & labor would be somewhere close to $1300-1400. I dickered & got my last regearing done for <$1200. 4.56 would be ideal for the 33" tire, 5-speed, and 4.0L engine combination.

This!! I just got my gears replaced last week with the 4.56 gears. I LOVE THEM!!! I have more power and the gas guage seems to be moving slightly slower. I'm still in the gear break in mode, so that might be the reason for the seemingly better fuel economy, but as far as the power and smooth operation goes, it's is fantastic. Wish I had done this sooner. My cost was about 1750.00 but then my spiders were worn out, the carriers had to be replaced as yours will, my axles were shot, he put in an upgraded limited slip rather than open diff. But I don't look back. Oh, and did I mention that I love those 4.56 gears? :punk:

Jad4271 04-16-2013 03:03 PM

I have 411's in my 9 inch rear and my motor hummms along at 2000 rpm at 70 mph with 33's. Thats good for me but keep in mind I did a 6.0 LS conversion so powers not an issue. Only gets 13 mpg BTW Jeeps are like bricks with wheels so I guess thats expected.

Patrick H 04-16-2013 03:06 PM

Quote:

Originally Posted by Jad4271 (Post 3644537)
I have 411's in my 9 inch rear and my motor hummms along at 2000 rpm at 70 mph with 33's. Thats good for me but keep in mind I did a 6.0 LS conversion so powers not an issue. Only gets 13 mpg BTW Jeeps are like bricks with wheels so I guess thats expected.

You can't compare 300HP to 190HP. ;)

Goalieme 04-16-2013 03:13 PM

I am in the same boat as you. I was running 33s on 3.07s. I chose to do alot at once and I just finished my ford 8.8 build. The Jeep is in the shop having Tru Trac's and 4.56s installed right now. Cannot wait to get her back and see what a difference it makes.

BTW I also did all 8 control arms, high clearance skid, SYE, and TW driveshaft at the same time. The Jeep has been down for about 3 weeks now. Super excited.

Jad4271 04-16-2013 03:15 PM

Quote:

Originally Posted by Patrick H (Post 3644548)
You can't compare 300HP to 190HP. ;)

Very true. My post was really just to give the op a reference of the cruising RPM with 33's and 411's. I'm not sure how the 4.0L responds to a decent hill when spinning at 2000 RPM plus I have an automatic so I don't have the annoyance of downshifting

BTW 300hp was just hurtful. LOL

Patrick H 04-16-2013 04:05 PM

Quote:

BTW 300hp was just hurtful.
How so? The 6.0L in my truck is rated @ 300HP, so that's what I was going by..

Jerry Bransford 04-16-2013 06:48 PM

Ha, he was just expressing a little envy over your 300hp... not that he didn't believe you. :)

Ogre22 04-16-2013 06:54 PM

I run 4:56 and 35in tires and I have plenty of power.

SeVeReDiStOrTiOn 04-16-2013 09:45 PM

Quote:

Originally Posted by Patrick H (Post 3644729)
How so? The 6.0L in my truck is rated @ 300HP, so that's what I was going by..

I think he's the guy that did a LS2 swap with LS6 intake manifold. That would be 400 bhp but i'm sure he has other mods or at least a tune.

Which 6.0 do you have? The LQ9 is rated at 345 bhp and 380ish torque...that's probably the one you have. Even the 5.3's have more than 300 bhp since the mid 2000's when GM put in electric fans...I think it went to 315? Not sure..

Patrick H 04-16-2013 10:11 PM

Quote:

Originally Posted by SeVeReDiStOrTiOn (Post 3646163)
I think he's the guy that did a LS2 swap with LS6 intake manifold. That would be 400 bhp but i'm sure he has other mods or at least a tune.

Which 6.0 do you have? The LQ9 is rated at 345 bhp and 380ish torque...that's probably the one you have. Even the 5.3's have more than 300 bhp since the mid 2000's when GM put in electric fans...I think it went to 315? Not sure..

LQ4 300HP, 360ft lb. The LM7 5.3 was rated at 285HP for that vintage.

JeepersCreep3rs 04-22-2013 06:45 AM

Quote:

Originally Posted by SpoiledRotten (Post 3644507)

This!! I just got my gears replaced last week with the 4.56 gears. I LOVE THEM!!! I have more power and the gas guage seems to be moving slightly slower. I'm still in the gear break in mode, so that might be the reason for the seemingly better fuel economy, but as far as the power and smooth operation goes, it's is fantastic. Wish I had done this sooner. My cost was about 1750.00 but then my spiders were worn out, the carriers had to be replaced as yours will, my axles were shot, he put in an upgraded limited slip rather than open diff. But I don't look back. Oh, and did I mention that I love those 4.56 gears? :punk:

How much did it cost you?


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