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Old 07-15-2012, 04:42 PM   #1
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another gearing question

hello all. As the title says I have a question about gearing but 1st things 1st...
I have a 98 4.0 automatic with 3.07 gears. I'm pretty new to lifting vehicles/offroading, but I'm not afraid to turn a wrench either.

I plan on moving up to 31/32 inch tires with a lift eventually. With these size tires would I need to regear and what gearing would be optimal? Currently this is my daily driver with 98% of the driving being on road so I would like to keep my mpgs and power. Any offroading would be moderately light being mainly dirt trails. I realize this is expensive to do, so I want it done right the 1st time.

with all that being said, any help?

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Old 07-15-2012, 05:10 PM   #2
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For a 31, it's not really worth the cost of regearing. You can put a 31 with stock height. For a 32, you will have to lift. Lets start with how much a lift you are planning.

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Old 07-15-2012, 08:50 PM   #3
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the plan is to lift 2 inches, 3 inches max.
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Old 07-16-2012, 12:01 AM   #4
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Quote:
Originally Posted by Neil F.
For a 31, it's not really worth the cost of regearing. You can put a 31 with stock height. For a 32, you will have to lift. Lets start with how much a lift you are planning.
31's on no lift will rub extremely bad and suspension travel will be extremely limited.

To properly for 31's you will not need a regear and a 2" spring puck budget boost lift will work, or 2" springs.

33's will fit with 2" lift and I 1" body lift. However with 3.07's you will want to regear.
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Old 07-16-2012, 12:22 AM   #5
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I had a 98 4.0 on 31"s and I didn't notice any lose in power at all so you should be good to just put the tires on and go
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Old 07-16-2012, 02:59 AM   #6
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Quote:
Originally Posted by Derp

31's on no lift will rub extremely bad and suspension travel will be extremely limited.

To properly for 31's you will not need a regear and a 2" spring puck budget boost lift will work, or 2" springs.

33's will fit with 2" lift and I 1" body lift. However with 3.07's you will want to regear.
I'm running 31s on stock and have no rubbing, any possibility it's different because I have an 01?
For the gearing, he will lose some of the power, I've noticed that in mine with 31s and 3.07s, 5th is hardly used unless on flat road, but again just my opinion.
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Old 07-16-2012, 03:03 AM   #7
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Originally Posted by JVLemur

I'm running 31s on stock and have no rubbing, any possibility it's different because I have an 01?
For the gearing, he will lose some of the power, I've noticed that in mine with 31s and 3.07s, 5th is hardly used unless on flat road, but again just my opinion.
Nope, they're all the same. you'll rub if you don't bumpstop correctly. Correctly bump'd you won't rub, you'll just lose uptravel in the shocks/whole suspension.
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Old 07-16-2012, 03:32 AM   #8
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Quote:
Originally Posted by Derp

Nope, they're all the same. you'll rub if you don't bumpstop correctly. Correctly bump'd you won't rub, you'll just lose uptravel in the shocks/whole suspension.
That's weird. I don't rub at all and the PO didn't do anything to the suspension, at least not that I was told, I have the stock springs and no pucks either.
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Old 07-16-2012, 03:40 AM   #9
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Quote:
Originally Posted by JVLemur

That's weird. I don't rub at all and the PO didn't do anything to the suspension, at least not that I was told, I have the stock springs and no pucks either.
Maybe he changed the bumps. Hmm.. everyone I've known has demolished their flares with 31's no pucks. Flex it out and see :o
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Old 07-16-2012, 03:48 AM   #10
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I'm also looking at 31's and I have an '01 TJ with 3.07's. I just want to keep my MPG's or get 2 or 3 more if I can. Not scared about losing my fenders as I only drive in town :P
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Old 07-16-2012, 03:50 AM   #11
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Quote:
Originally Posted by JVLemur

That's weird. I don't rub at all and the PO didn't do anything to the suspension, at least not that I was told, I have the stock springs and no pucks either.
Never disconnect your swaybar, right? Fully flexed with 31s you'll definately cause some damage if not properly bumpstopped.
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Old 07-16-2012, 03:50 AM   #12
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Quote:
Originally Posted by Derp

Maybe he changed the bumps. Hmm.. everyone I've known has demolished their flares with 31's no pucks. Flex it out and see :o
Hmm I'll have to check now, well in the day time anyways, I'll try and find somewhere to flex it haha.
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Old 07-16-2012, 03:59 AM   #13
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Quote:
Originally Posted by Rolf

Never disconnect your swaybar, right? Fully flexed with 31s you'll definately cause some damage if not properly bumpstopped.
Yep, that's what I was thinking lol
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Old 07-16-2012, 04:02 AM   #14
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Quote:
Originally Posted by Rolf

Never disconnect your swaybar, right? Fully flexed with 31s you'll definately cause some damage if not properly bumpstopped.
Ah no never have, I have yet to do any wheeling, and I've been trying to educate myself in how the wranglers work completely(I'm kind of a nerd in ways) and I'm very thankful of this forum and all the help I've gotten from all the fellow jeepers.
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Old 07-16-2012, 04:57 AM   #15
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MANY run 31's without any issues. Rubicons are stock with 31 and the Rubicon suspension is exactly the came height as all other TJs.
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Old 07-16-2012, 11:56 AM   #16
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Quote:
Originally Posted by Neil F.
MANY run 31's without any issues. Rubicons are stock with 31 and the Rubicon suspension is exactly the came height as all other TJs.
I don't think he's got a rubicon.
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Old 07-16-2012, 12:45 PM   #17
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Now that I think about it I would have been fine with 31s had I not had my heavy-ass bumper and winch on the front-end.
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Old 07-16-2012, 01:17 PM   #18
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I don't think he's got a rubicon.
The point is you said 31 will rub all over the place. My point is Rubicons with the same suspension as every other TJ do not rub.
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Old 07-16-2012, 01:56 PM   #19
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The point is you said 31 will rub all over the place. My point is Rubicons with the same suspension as every other TJ do not rub.
IIRC Rubicon suspensions are not exactly the same - 1" taller than stock TJ...
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Old 07-16-2012, 01:57 PM   #20
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IIRC Rubicon suspensions are not exactly the same - 1" taller than stock TJ...

Nope. Same height. Do a search on Rubicon springs. It has been discussed plenty when people have asked about using Rubicon springs for a lift.
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Old 07-16-2012, 03:47 PM   #21
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He doesn't have a rubicon theirfore your claim is irrelevant theirfore your comment means nothing.
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Old 07-16-2012, 05:52 PM   #22
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guys, back to the topic at hand.....this got a little out of hand

I don't have a Rubicon or a 5 speed. I'm really just looking for info pertaining to my 1998 4.0 3spd auto with 3.07 gears....

I don't want 31s with no lift, I would like to lift 2/2.5 inches and run 31s or 32s. Seeing as this is my daily driver I don't think I'll be running 33s or adding much more lift than I already plan on.

that being said I have 3.07 gears, would it be beneficial to regear/swap axles and what would the benefits be. How will it effect mpg and power and highway driving
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Old 07-16-2012, 06:03 PM   #23
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Quote:
Originally Posted by 98SaharaTJ
guys, back to the topic at hand.....this got a little out of hand

I don't have a Rubicon or a 5 speed. I'm really just looking for info pertaining to my 1998 4.0 3spd auto with 3.07 gears....

I don't want 31s with no lift, I would like to lift 2/2.5 inches and run 31s or 32s. Seeing as this is my daily driver I don't think I'll be running 33s or adding much more lift than I already plan on.

that being said I have 3.07 gears, would it be beneficial to regear/swap axles and what would the benefits be. How will it effect mpg and power and highway driving
If you want a 2.5 lift and ya a DD do a BB like teraflex or RE, re-gearing to run the 31s would be expensive for unnecessary reasons I believe, itll run on the 3.07s you'll just lose some mpgs and some power, not bad enough to spend $500+ to go up to either 3.73 or 4.10s. Again, my opinion.
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Old 07-16-2012, 06:06 PM   #24
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If you want a 2.5 lift and ya a DD do a BB like teraflex or RE, re-gearing to run the 31s would be expensive for unnecessary reasons I believe, itll run on the 3.07s you'll just lose some mpgs and some power, not bad enough to spend $500+ to go up to either 3.73 or 4.10s. Again, my opinion.
so what your saying is if I ran 3.73 I would retain the mpg and power?
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Old 07-16-2012, 06:10 PM   #25
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Originally Posted by 98SaharaTJ

so what your saying is if I ran 3.73 I would retain the mpg and power?
From my understanding it would help regain the mpgs and power loss from upgrading to bigger tires, like I said I run 31s on the 3.07s 5th is useless and I'm getting 13mpg in a good day. I'm not complaining as I expected the gas consumption, but i wouldn't mind seeing 16mpg.
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Old 07-20-2012, 05:57 AM   #26
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From my understanding it would help regain the mpgs and power loss from upgrading to bigger tires, like I said I run 31s on the 3.07s 5th is useless and I'm getting 13mpg in a good day. I'm not complaining as I expected the gas consumption, but i wouldn't mind seeing 16mpg.
He's running a totally different tranny though(32RH iirc) which is the auto w/o overdrive - meaning his gearing is much different than yours. This means it's a whole different ball game when you get into MPG's and RPM's. I've looked carefully into this matter as I'm making this exact switch in a couple days(4.0L I6 32RH 3.07 D35). I'll be sure to report back.

One question though: right now, are your RPM's about 2150 @ 60 MPH? Between the 2 and the little dot? I checked the Grimm Jeepers calculator and it said we would only lose about 100 RPM's after the switch to 31's. I think that keeps it in the healthy power band for our I6, so you might even get +1 or +2 MPG's!

Can't hurt to be optimistic!
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Old 07-20-2012, 06:56 AM   #27
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Quote:
Originally Posted by MetalArmageddon

He's running a totally different tranny though(32RH iirc) which is the auto w/o overdrive - meaning his gearing is much different than yours. This means it's a whole different ball game when you get into MPG's and RPM's. I've looked carefully into this matter as I'm making this exact switch in a couple days(4.0L I6 32RH 3.07 D35). I'll be sure to report back.

One question though: right now, are your RPM's about 2150 @ 60 MPH? Between the 2 and the little dot? I checked the Grimm Jeepers calculator and it said we would only lose about 100 RPM's after the switch to 31's. I think that keeps it in the healthy power band for our I6, so you might even get +1 or +2 MPG's!

Can't hurt to be optimistic!
Correct except there is no overdrive. A good swap if you have a d35 is the d30/35 from a 2.5 that has 4.10s. Because that is the exact gearing we need (with 33s) and the 32rh. And locally I can pull axles for 150 a piece. So I'm out 300 plus time. Minus the resale of my axles.
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Old 07-20-2012, 07:52 AM   #28
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Unfortunately, I'm all too familiar with the 32RH not having OD lol there is no emoticon sad enough to express it. When I'm forced to drive down I-5 it physically hurts me to hear my engine revving so high!

Anyways, I thought 98SaharaTJ wanted 31's with his stock 3.07's? I would definitely agree that a D35 swap from a 2.5L with the 4.10's would suit the 33's well. Any bigger though and you might need the 4.56's. I hear 4.56 x 35's makes for a great combo! I actually think I'm gonna buy the 31's today and see how they are. Hopefully the used place I'm buying from will let me return 'em if my mileage goes Titanic on me :P
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Old 07-20-2012, 10:03 AM   #29
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Quote:
Originally Posted by MetalArmageddon
Unfortunately, I'm all too familiar with the 32RH not having OD lol there is no emoticon sad enough to express it. When I'm forced to drive down I-5 it physically hurts me to hear my engine revving so high!

Anyways, I thought 98SaharaTJ wanted 31's with his stock 3.07's? I would definitely agree that a D35 swap from a 2.5L with the 4.10's would suit the 33's well. Any bigger though and you might need the 4.56's. I hear 4.56 x 35's makes for a great combo! I actually think I'm gonna buy the 31's today and see how they are. Hopefully the used place I'm buying from will let me return 'em if my mileage goes Titanic on me :P
I misread your first post, my apologies. What gearing/ tires do you have now?
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Old 07-20-2012, 12:54 PM   #30
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Correct except there is no overdrive. A good swap if you have a d35 is the d30/35 from a 2.5 that has 4.10s. Because that is the exact gearing we need (with 33s) and the 32rh. And locally I can pull axles for 150 a piece. So I'm out 300 plus time. Minus the resale of my axles.
Completely disregarded the 32rh, and was mostly stating a regear would help, but either way, wouldn't it be better to upgrade the rear to a ford 8.8 with the 4.10s as opposed to a D35?

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