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Old 05-17-2010, 07:26 PM   #1
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Change Gear Ratio

I have a Dana 30 for a front axle and a Dana 44 in the rear. Bought an 08 Jeep JK 4 door used recently and thought it had the 3:73 gears. Actually has the 3:21 gears.

I've mostly owned 70's 80's GM cars in the past (Mostly Trans Ams and Camaros) and I've setup a few rear ends before. Is there anything special to changing out the gears in the Dana axles? Will the carriers in these axles support 3:73 gears without needing thick gears?

Looking for some quick way to change the gears out without rebuilding both axles...

3:21 poop.

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Old 05-17-2010, 08:18 PM   #2
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Didn't the X come from the factory with 4:1 gears in 2007? I'm pretty sure that peoples are running that ratio without problems.

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Old 05-18-2010, 08:37 AM   #3
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X

I think 3 ratios were offered. 3:21, 3:73, and 4:10. I found both 3:73 used rings and pinions out of non rubicon front and rear Dana axles on Ebay but just didnt know if the gear sets worked with the carriers I had in my Jeep currently that had the 3:21 gears.

Anyone know if 3:73 gears willl work for sure?
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Old 05-18-2010, 01:11 PM   #4
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I know. Cuz I have 3.21 gears. I have 3.73s on the way, and already tried a 4.10 in the rear.

The rear D44 3.73 will go right in.

The front D30 needs a new carrier for 3.73 and higher gearsets, so you need a new carrier also.

Those are some high priced gearsets on ebay.. i just got mine for $20 and $35 plus shipping.
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Old 05-18-2010, 03:33 PM   #5
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I know. Cuz I have 3.21 gears. I have 3.73s on the way, and already tried a 4.10 in the rear.

The rear D44 3.73 will go right in.

The front D30 needs a new carrier for 3.73 and higher gearsets, so you need a new carrier also.

Those are some high priced gearsets on ebay.. i just got mine for $20 and $35 plus shipping.

And I believe the D44 will need a new carrier if you go over 4:10.
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Old 05-20-2010, 06:37 PM   #6
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Thx for the info on the front axle carrier. Where'd you find gears for 20 bucks?
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Old 05-20-2010, 06:39 PM   #7
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ebay. just got my rear 3.73 installed. not positive i like it. ill have to try it for a few days.
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Old 05-21-2010, 11:56 AM   #8
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Ok ok- let's get this straightened out.
The carrier break for the front is 3.73, so you'll need a new carrier (diff) up front to go to anything 3.73 and above.
The JK rear carriers do NOT have a break. Regardless of gearing, you need a 3.91 and DOWN carrier (diff)- the bigger style will NOT fit! Trust me on this one.

As for ring and pinion gears, you NEED JK-specific gears, or they will not fit.


Plac, what do you mean you had your REAR 3.73 installed? Not the front?? I'm confused- Mark W.
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Old 05-21-2010, 01:54 PM   #9
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Ok ok- let's get this straightened out.
The carrier break for the front is 3.73, so you'll need a new carrier (diff) up front to go to anything 3.73 and above.
The JK rear carriers do NOT have a break. Regardless of gearing, you need a 3.91 and DOWN carrier (diff)- the bigger style will NOT fit! Trust me on this one.

As for ring and pinion gears, you NEED JK-specific gears, or they will not fit.


Plac, what do you mean you had your REAR 3.73 installed? Not the front?? I'm confused- Mark W.
front coming a week later. i do a 2 hour appt after work. one at a time.
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Old 05-21-2010, 10:17 PM   #10
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Gotcha. Just hope you don't need 4WD in that time! Mark W.
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Old 05-22-2010, 07:51 AM   #11
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Just wanted to verify that I could change to 3.73 in the rear and do the front axle later AS LONG as I don't use 4WD until I get the 3.21 gear set out of the front axle? Only want to swap one gear set at a time just due to time limitations.

Plac. What didn't you like about the 3.73? Was it not enough of a change rpm/torque wise or did it take away too much top end on the expressway? I'm towing a boat with my Jeep right now and really need to get something 3.73 or higher in the difs soon. I didn't want to go 4.10 or above and and find out I could only go 60mph on the highway turning some really high rpm.
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Old 05-22-2010, 10:27 AM   #12
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Just wanted to verify that I could change to 3.73 in the rear and do the front axle later AS LONG as I don't use 4WD until I get the 3.21 gear set out of the front axle? Only want to swap one gear set at a time just due to time limitations.
Thats correct. I do it that way for the same reasons of time mostly, and also to make sure i am positive about my gear choice before I spend labor money on both. If you end up staying with them, then you get lucky and only pay for each axle once.


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Plac. What didn't you like about the 3.73? Was it not enough of a change rpm/torque wise or did it take away too much top end on the expressway? I'm towing a boat with my Jeep right now and really need to get something 3.73 or higher in the difs soon. I didn't want to go 4.10 or above and and find out I could only go 60mph on the highway turning some really high rpm.
Dood, don't worry about me. I'm probably the pickiest person in the world, and the only guy that could possibly not like 3.73s'. The top end/revs/freeway is NOT the reason. These are just fine everywhere. 5th gear can cruise 80mph at 3000rpms, and then i have a whole nother gear to pop into. 6th brings me to 2600-2700 at 80mph if i remember correctly. (But I do prefer 2300rpm/80mph/6th with my 3.21's.) As long as you are going 75+ with 3.21's, 6th gear works fine.

For towing, you have no choice to go at LEAST 3.73's. Remember 3.73s only have a 2000 tow rating anyway, make sure you are in spec. 4.10's bring it up even higher. 3.21's only have a 1000 lb tow rating but it doesnt matter cuz i dont tow. You need to find out the weight of your boat before you make your final decision. If you are towing NOW with 3.21's and your boat weighs more than 1000 lbs you could easily blow up your diff.
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Old 05-23-2010, 04:00 PM   #13
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Put it this way- I ran 4.88's and 31's in my 6-speed, and could still do 70 MPH down the highway. I was over 3K RPM's, but it's not a problem. The 6-speed has plenty of overdrive. Go with 4.10's. Trust me. If you're towing, the extra bit of torque will be much appreciated. I'd also HIGHLY recommend going to synthetic gear oil in the diffs, and a Superchips tuner for a few extra ponies- Mark W.
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Old 05-23-2010, 04:13 PM   #14
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yup, even im gonna do a superchips soon. whether im on 3.21's or 3.73's. it will help either way.
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Old 05-23-2010, 08:34 PM   #15
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4.56 Ratio.

Think I'm gonna end up going with the 4.56 mainly for towing. I tow a 3300lbs boat (3300lbs includes the weight of the trailer) through some pretty steep hills and want some pretty good torque to pull. I really don't cruise more than 70 on the highway. Anyone know what roughly the rpm in 6th gear is with 4.56's?

I found a 4 wheel drive shop down this way that will swap both ring and pinion front and rear and add the new carrier for the Dana 30 in the front for 2000.00 parts and labor. That seem to terrible to anyone price wise? Prob gonna get this done pretty soon.

Thx for all the replies. Really helping me out in figuring which ratio so far will prob work best.
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Old 05-23-2010, 08:45 PM   #16
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Think I'm gonna end up going with the 4.56 mainly for towing. I tow a 3300lbs boat (3300lbs includes the weight of the trailer) through some pretty steep hills and want some pretty good torque to pull. I really don't cruise more than 70 on the highway. Anyone know what roughly the rpm in 6th gear is with 4.56's?

I found a 4 wheel drive shop down this way that will swap both ring and pinion front and rear and add the new carrier for the Dana 30 in the front for 2000.00 parts and labor. That seem to terrible to anyone price wise? Prob gonna get this done pretty soon.

Thx for all the replies. Really helping me out in figuring which ratio so far will prob work best.
6th gear, 70mph, 4.56, probably 2900-3000rpms.

huge rip off dude. way overpriced. i got a quote parts and labor for $1200-$1300 everything including the new carrier.
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Old 05-23-2010, 08:56 PM   #17
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^ Agreed. New carrier is ~$125, new R&P's about $400, rebuild kits ~$300. Labor ~$500-750 is reasonable.
Also, I would NOT recommend 4.56's if the rig is only an occasional tow rig. As I said, 4.10's with 32's would be a solid idea. Lower than that would be a waste- throwing away gas mileage. The LK is still rated to 3,500 Lbs. towing even with 3.21's. It's more of an issue with the 2-door, which has different ratings by gearing. Anyway, either way you go, best of luck, and enjoy! Mark W.
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Old 05-24-2010, 12:56 AM   #18
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Parts and Labor

I moved from Toledo OH to Austin, TX back in 04' and definitely miss the automotive folks from back up north. Speciality shops and people with automotive skills are pretty much everywhere. I have yet to find a shop I like down this way and prices always seem pretty high due what I think is probably a lack of automotive talent and probably a shortage of auto mechanics in this area.

So I should probably figure 850 for parts and 500 - 750 for labor? Place with the 2000.00 quote came from Truck Parts & Truck Accessories in Austin, TX 78757-RH1 here in Austin. This has been about the only shop I've found down in this area that really had a clue what I was looking to do and didn't think regearing was a "big job". Anyone know of a good place down in Austin to take a job like this?

3000 rpm at 70mph with 4:56 gears does seems a bit too high. I'll prob order some 4:10's then. What's the best place to order the carrier and gears? Should I go with factory OEM parts from the dealer or get them online?

Thx...
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Old 05-24-2010, 07:29 AM   #19
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ive bought all my gear sets used.. some for $20 a set.. ebay. JK Jeep only, others wont fit. used is better to me, as it doesnt require the pain in the ass break in, like no speeds over 50mph for at least 100 miles, and 30 min cool down breaks every 20-25 miles couple times.

last week i got my 3.73 front and rear set for about $80 shipped total to my door. and you dont need any rebuild kit if your Jeep is low miles. They have never used a rebuild kit on mine yet. (18,000 miles) My shop has been around 20+ years and ONLY does rear ends.
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Old 05-24-2010, 08:23 AM   #20
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You may be able to find a set of JK D30/D44 4.10's online- I had a set I sold a few months ago. Make SURE you get JK gears- TJ or other gears WILL NOT FIT!

Otherwise, Jeep Parts - Jeep Accessories - Lift Kits - Free Shipping at 4WS.COM Call and talk to Jeff. He's a bit clueless sometimes, but he'll hook you up. Get the Yukon D30 3.73 and up empty case, and their internals (gears) for it, Superior overhaul kits (again, for a JK), and JK-specific gears. They ship free, and know their stuff- Mark W.
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Old 05-24-2010, 08:32 AM   #21
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You may be able to find a set of JK D30/D44 4.10's online- I had a set I sold a few months ago. Make SURE you get JK gears- TJ or other gears WILL NOT FIT!

Otherwise, Jeep Parts - Jeep Accessories - Lift Kits - Free Shipping at 4WS.COM Call and talk to Jeff. He's a bit clueless sometimes, but he'll hook you up. Get the Yukon D30 3.73 and up empty case, and their internals (gears) for it, Superior overhaul kits (again, for a JK), and JK-specific gears. They ship free, and know their stuff- Mark W.
my used rear 4.10 JK gear set just sold on ebay a few days ago for $49 shipped.
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Old 05-24-2010, 04:19 PM   #22
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Same shop down here told me that used gears would more than likely howl or be noisy even if setup correctly. They have no problem with me buying parts from other sources but just don't seem very interested in installing a used gear set.

Any of this sound right or should I just hunt down some used gear sets? I've got 44,600 on the front and rear axle currently. They also wanted me to buy the rebuild kits. Any problems with using the existing internals with this low of mileage? I'm gonna buy the front carrier for 59.00 bucks and 94.00 for the spider gears both brand new with free shipping. I'd like to get the gears used for cost sake if it for sure won't cause me any problems.
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Old 05-24-2010, 05:28 PM   #23
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Alright. Found a shop down here in Austin, TX called Austin Drive Train Inland Truck that seems to know their stuff so far in case anyone is looking for a shop that isn't scared to tackle a gear swap. Said he already has 4.10 gears for my Dana 30 and 44 that he could use from other JK swaps and has a used carrier for my Dana 30 too. Quoted 750.00 for labor and the whole job shouldn't run over 1300.00 max. (Won't lock in anything lower without knowing the BM number on the axles first.) I'll post back how this all turns out in a few weeks.

Thx to everyone for the help figuring out the best ratio and decent labor costs. I'll never buy another Jeep without checking the ratio first. I never thought there'd be a 3.21 in a Jeep with a factory trailer harness and tow hitch.

Found a ratio chart on this forum too in case anyone ever runs across this thread and wants to know roughly what RPM at 70mph a JK with a 3.8 will turn depending on tire size and gear ratio.

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Old 05-24-2010, 06:41 PM   #24
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As for rebuild kits, I recommend getting one just in case- you always run a risk of busting the carrier bearings when pulling them off, and holding up a swap for one bearing SUCKS- trust me After more than a couple K miles, I always swap bearings- too inexpensive to replace, vs. a couple hundred to pull it all apart again later- no thanks! As for used gears, they CAN howl when re-installed- it's a risk, and there is no guarantee they won't. As long as they're set up right, and aren't pitted, chipped, or scarred, you SHOULD be fine, however- Mark W.
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Old 05-24-2010, 06:53 PM   #25
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Same shop down here told me that used gears would more than likely howl or be noisy even if setup correctly. They have no problem with me buying parts from other sources but just don't seem very interested in installing a used gear set.

Any of this sound right or should I just hunt down some used gear sets? I've got 44,600 on the front and rear axle currently. They also wanted me to buy the rebuild kits. Any problems with using the existing internals with this low of mileage? I'm gonna buy the front carrier for 59.00 bucks and 94.00 for the spider gears both brand new with free shipping. I'd like to get the gears used for cost sake if it for sure won't cause me any problems.
of course they did..

dont listen to them. i've had 3 used ring/pinions installed so far. no issues.
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Old 06-22-2010, 10:44 PM   #26
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Ratio change finally to 4.88's

I ended up having the gear swap done at a local shop here and decided on 4.88's. I still have the stock 32" tires on my Jeep and this ratio has been excellent for me so far. At 70MPH RPM's are a little over 3k (I have the 6 speed btw). I don't really drive my Jeep much over 65MPH so this was pretty much ideal for me.

I tow a 21' Pontoon with my 4 door JK (which weighs in over 3000lbs with the tralier included) pretty frequently and beach launch it without a ramp which is where the 4x4 of the Jeep comes in. I'm gonna trailer it for the first time this weekend with the 4.88's but I can already tell this ratio will work really well towing wise.

Thanks for all the info and feedback. The gear ratio chart I found on here really helped in figuring out which ratio would work best for my situation.

Total cost with parts, labor and tax ended up being 1500.00. Changed from 3.21 to 4.88.
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Old 01-05-2011, 12:06 PM   #27
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will the ring and pinion 3.73 set both front and back off of a 2010 Jeep wrangler be compatable with the 2011. I am assuming so I am sure that interior cosmetics were the only changes to the Jeep. I do know i need a new carrier to move up from the 3.23 to 3.73 on the dana 30 on my front end but the rear Dana 44 will not require a carrier change. Is this info correct because i have found a set of 3.73 gears really cheep with only 200 mile on them and would like to change it but want to make sure 2011 dont have a new Ring and Pinion design from the 2010 model.
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Old 01-05-2011, 04:54 PM   #28
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Thats on the fifth gear .
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Old 01-05-2011, 05:11 PM   #29
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Thats on the fifth gear .
Is the speed actually governed at 100 mph or does the speedo just stop there? That's insane, by the way.
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Old 01-05-2011, 05:22 PM   #30
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On the automatic chart up there, is the numbers right? If so it is saying the gears for a stock automatic with 32" tires and 3.73 gears are not even close to the correct gearing needed.

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