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Old 02-16-2010, 03:59 PM   #1
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Question HELP... Building my 08 JK

After saving $$$ for the past year and a half. I am finally modifying my Jeep, and I need some help. I am not mechanically inclined so bare with me.

I have a 2008 Wrangler X with the S package which added options including the 17 inch alloy wheels.

To date, this is what I have ordered in the past week:

Rugged Ridge Modular XHD front and rear bumper in powder coat black
Rugged Ridge XHD rear tire rack
Rugged Ridge 4 inch tubular side steps
Front skid plate
Rough Country 3.25 inch suspension lift kit
Rough Country Perf. Dual Stabilizer
1.5 inch wheel spacers to accomodate running my stock rims with 35 inch tires

Most of these things have either arrived in the past few days or are hopefully being shipped soon, but I have some questions.

I believe my gear ratio is 3.73. I plan to run 35s which will be a 3 inch increase over the stock 32s. Do I need to start considering upgrading my gear ratio to 4.10 or higher to accomodate the 35s? I don't want my JK to be a slug on the road. It is my only vehicle and I will be using it mostly for regular highway driving.

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Old 02-16-2010, 04:12 PM   #2
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I believe my gear ratio is 3.73. I plan to run 35s which will be a 3 inch increase over the stock 32s. Do I need to start considering upgrading my gear ratio to 4.10 or higher to accomodate the 35s? I don't want my JK to be a slug on the road. It is my only vehicle and I will be using it mostly for regular highway driving.
Is it an auto or manual. If manual you can probably get by with 3.73. But check your sticker, unless you got the tow package or optional gearing it came with 3.21 gears.

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Old 02-16-2010, 04:29 PM   #3
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Sorry, It's a 6 speed manual... I don't have the window sticker unfortunately and I don't know how else to figure it out. I rechecked online and found this website

Project-JK.com - Jeep JK Wrangler Resource » Jeep JK Wrangler Axle Basics

I misread it the first time. After 2007, They changed the front axle ratio from 3.21 to 3.73 in the 2008. The rear remained 3.21 in the DANA 35. But then it reads in the DANA 44 "In 2008, the only optional factory gear ratio available is now 3.73."

I just went out and crawled under my Jeep...my rear axle definately looks like the DANA 44 as pictured on that website I linked
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Old 02-16-2010, 05:04 PM   #4
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Front and rear are the same gearing always
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Old 02-16-2010, 05:58 PM   #5
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So does this mean my gear ratio is 3.73? And if so, with a manual 6 speed. Should I be fine running 35s??

Thanks for any advice any of you may have
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Old 02-16-2010, 10:09 PM   #6
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Also, is there a fairly reasonable priced solution to adding more power to my JK to compensate the added weight and larger tires?
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Old 02-17-2010, 08:37 AM   #7
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For 35's I would probably look at 4.88 gear ratio. You could get by with 4.10. But 4.88 will give you a good amount of power without sacrificing too much in mpg. 4.10s will give you the best mileage but you will notice the loss in power.

Might also, if you can afford it, look into get a superchips flashpaq for your Jeep. That will help with power and overall performance of your Jeep
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Old 02-17-2010, 09:17 AM   #8
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For 35's I would probably look at 4.88 gear ratio.
I agree.
But I don't think they'll fit if you have 3.21's stock; you should run your vin at a dealer to make sure what's in there first.
If you've got 3.21's, you might want to order a d44 front axle with 4.88's and only need to regear the rear.
Also a great opportunity to add a locker while it's apart.
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Old 02-17-2010, 02:56 PM   #9
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So I just called the dealer, they ran my vin...and disappointed to say, I have 3.21 gears. I have a small mountain of boxes in my garage of parts to lift my Jeep 3.25 inches, put 35s, side rails, bumpers....ect. all ready to be put on this week.

Anyone know How much is it gonna run me to upgrade my gear ratio to atleast 4.10 or preferably 4.88??
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Old 02-17-2010, 03:14 PM   #10
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See how it drives post lift and tires. You will still probably want to regear it but thats not something that has to be done immediately. 4.88's go for about $170 on quadratec but I have no I idea how much it would cost to have them put in.
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Old 02-17-2010, 03:18 PM   #11
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Superior Axle and Gear D30488RJK - Superior Axle & Gear Ring and Pinion for 07-10 Jeep® Wrangler & Wrangler Unlimited JK with Dana 30 Front Axle - Quadratec

Superior Axle and Gear D44488JK - Superior Axle & Gear Ring and Pinion for 07-10 Jeep® Wrangler & Wrangler Unlimited JK with Dana 44 Rear Axle - Quadratec

Is this what I need to order? It looks like this fits into the D44 rear and D30 front differentials. Then find some auto shop to install it, cause I know I am not skilled enough to rip my differentials open
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Old 02-17-2010, 03:19 PM   #12
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Originally Posted by Tpr5318 View Post
Anyone know How much is it gonna run me to upgrade my gear ratio to atleast 4.10 or preferably 4.88??
^I got the same problem...
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Old 02-17-2010, 03:53 PM   #13
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Well I just called a few automotive shops in the area, they actually recommended me to go right thro Chrysler/Jeep Dealer. Sounds like it might be a pretty costly and complex step. I called my local Jeep dealer and they are gonna look into what itll cost in labor to put those 4.88 gears into the D44 and D30.

I am suppose to call them back tomorrow morning to find out.
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Old 02-17-2010, 04:07 PM   #14
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Well I just called a few automotive shops in the area, they actually recommended me to go right thro Chrysler/Jeep Dealer. Sounds like it might be a pretty costly and complex step. I called my local Jeep dealer and they are gonna look into what itll cost in labor to put those 4.88 gears into the D44 and D30.

I am suppose to call them back tomorrow morning to find out.
hmmm thats interesting... I would imagine that bill is gonna be astronomical.
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Old 02-17-2010, 04:08 PM   #15
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Might also, if you can afford it, look into get a superchips flashpaq for your Jeep. That will help with power and overall performance of your Jeep

I might do this as well. This isn't outrageously expensive. I just want to do it all right the first time. Even if it costs a little extra $
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Old 02-17-2010, 04:09 PM   #16
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hmmm thats interesting... I would imagine that bill is gonna be astronomical.
I am open to other options if you have any ideas ha ha
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Old 02-17-2010, 06:29 PM   #17
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Ive found several websites that say the 2008 Wrangler X only came factory 3.73 axle ratio, or 4.10 tow package....

However the Jeep Dealer says my 2008 has a 3.21....hmmm

In addition to regearing the D30 and D44 to 4.88. If I do have a 3.21 stock.... Looks like I also have to order a new carrier to allow the usage of 4.88 gears with the D30.

FML...everytime I find one thing, it requires another. This is gonna cost me $$$$
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Old 02-17-2010, 07:15 PM   #18
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However the Jeep Dealer says my 2008 has a 3.21....hmmm

In addition to regearing the D30 and D44 to 4.88. If I do have a 3.21 stock.... Looks like I also have to order a new carrier to allow the usage of 4.88 gears with the D30.

FML...everytime I find one thing, it requires another. This is gonna cost me $$$$
That all sounds correct to me, I have an 08 and I got the tow package which upgraded the gears from 3.21 to 3.73.. The only 08s that have 4.10s are Rubicons.

Seeing as you have a manual, I would go ahead and do the lift and tires and see how it drives. It will probably be like starting in 2nd and 6th will be useless, but other than that it will probably be OK until you can sort the gearing out. If it really drives that bad you can put the stock tires back on until you get the gears.
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Old 02-17-2010, 07:31 PM   #19
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Thanks for the input. I will go that route. Run the 35s with factory gearing until I can upgrade to 4.88. I may do the superchip as well. I'll have myself a decent machine and about 5k less in my wallet lol
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Old 02-17-2010, 07:41 PM   #20
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Mine is a 08 X that came with 3.07's it was a dog,even with 32's.Mileage was ok with them and 32's @ 15 mpg then got it lifted new gears (4.88's) and 35's now mileage is right at 13 but I can use 6th gear now.You will be upgrading soon 'just a guess
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Old 02-17-2010, 07:44 PM   #21
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got it lifted new gears (4.88's))
Did you regear it yourself? If not, how much did it run you. I assume you also had to by a new carrier for the 4.88 gear in the front D30?
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Old 02-17-2010, 08:31 PM   #22
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Mine is a 08 X that came with 3.07's it was a dog,even with 32's.Mileage was ok with them and 32's @ 15 mpg then got it lifted new gears (4.88's) and 35's now mileage is right at 13 but I can use 6th gear now.You will be upgrading soon 'just a guess
3.07 ?? Never heard of a 3.07 gears, at least not in a JK? 3.07 was standard for some TJs.
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Old 02-17-2010, 09:39 PM   #23
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Thanks for the input. I will go that route. Run the 35s with factory gearing until I can upgrade to 4.88. I may do the superchip as well. I'll have myself a decent machine and about 5k less in my wallet lol
Superchips is great idea, I run 35's with stock gearing but I have the superchips tuner and it really picks up the slack. As for the gearing issues call Dave at Northridge 4x4 (360) 340-0282 and they can answer all your gearing questions.
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Old 02-17-2010, 09:54 PM   #24
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Superchips is great idea, I run 35's with stock gearing but I have the superchips tuner and it really picks up the slack. As for the gearing issues call Dave at Northridge 4x4 (360) 340-0282 and they can answer all your gearing questions.

What was you're stock gearing? 3.21 or the upgraded 3.73? I may give him a call for some advice, thanks for the tip!....being from New York State and Northridge Auto being in the state of Washington, idk that I can use them to actually regear it tho lol.

Anyone know if running 35s on the stock 3.21 actually causes damage to the vehicle?

I'm still interested to know if most of you guys out there regeared your jeeps yourselves or had it done professionally? Those done professionally. I am interested to hear what you paid so I know if the quotes I get are good or not
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Old 02-17-2010, 10:21 PM   #25
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What was you're stock gearing? 3.21 or the upgraded 3.73? I may give him a call for some advice, thanks for the tip!....being from New York State and Northridge Auto being in the state of Washington, idk that I can use them to actually regear it tho lol.

Anyone know if running 35s on the stock 3.21 actually causes damage to the vehicle?

I'm still interested to know if most of you guys out there regeared your jeeps yourselves or had it done professionally? Those done professionally. I am interested to hear what you paid so I know if the quotes I get are good or not
mine is 3.73 auto and running 35's with 3.21 gears is not going to hurt anything, you would need to be careful when you go off road but daily driving isn't going to hurt.
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Old 02-18-2010, 07:07 AM   #26
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I'd still take the opportunity to get a new front axle if you're set on the idea of 35's.

I'll pm Antigoon and have him chime in for you; he's a retired driveline engineer and is the authority on this stuff around here. The rest of us are amateurs...
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Old 02-18-2010, 08:25 AM   #27
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First of all ..whatever you do it will cost you some $$.. The end result should be one you like .. Indeed there are Jeepers who have a 3.21 and are running 35" tires with a manual tranny..Will it work YES..will you do damage.. NO.. will you be satisfied as a Jeeper..NO

To do it right you have the choice to go to 4.10 or 4.88.. A 4.10 is a min to go for..All depends what kind of off roading you plan on doing..
If mileage is no issue.. go with the 4.88
Following most of these threads I noticed that NO one complained about a "over gearing" condition..A lot are saying, I wish I went up a notch.. So my choice is the 4.88...(I have a 3.21 as well and once I decide on re-gearing I will go for the 4.88..
Another word of caution.. Don't try to do this yourself..This is more then just replacing some gears..You need to measure some key dimensions in order to select the right shims assuring a proper gear bearing pattern otherwise you will have premature wear and noise. Also you need to have the right tools and knowledge to do this job the right way..Therefore, find a good and reliable re-gearing shop.. I understand this will not be cheap.. But we love Jeeping so the $$ "shock" is part of the "no pain, no gain" equation..

Good Luck...

You also might look into this chart

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Old 02-18-2010, 08:37 AM   #28
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These guys are giving you really good data, but

Nobody has mentioned your 3 1/4" lift, for a daily driver

Your U-joints/shifting/alignment/steering are all going to be affected, some a lot. some a little, but be advised that you're in for a long heavy maintenance program, which is normal-if you expect it

Good luck-you're in the JEEP world

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Old 02-18-2010, 10:11 AM   #29
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Wow. Thanks alot for all the info. I really appreciate it. You guys are awesome.

I expected the lift to add some changes and issues with the steering, alignment ect. I purchased the dual stablilizer from rough country that will hopefully help with some of this. I am not nieve tho.....I know that this is going to be a completely different vehicle once it's put together.

Thanks again everyone. You have all really helped
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Old 02-18-2010, 10:21 AM   #30
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OOPS, I forgot to add, the dual stabilizer is NOT GOOD for any light duty vehicle, (steering/tierod/pullys/joints)-overload

It puts TOO MUCH of a load for ALL YOUR NORMAL steering and your steering pump has too work OVERTIME-ALL THE TIME

OK, for the 3/4--1-ton trucks--NOT JEEPS

Not that it won't work-for a while, then probably the "Death Wobble"

Like most jeep mods-just be ready for surprises !!

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