Confused about re-gearing my 99 TJ 4.0 5-speed

TamaDrummerJeepGuy

TamaDrummerJeepGuy

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Joined
Mar 29, 2021
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4
Location
Omaha, Nebraska
Hello and thanks in advance for any help!!
Before anyone mentions it, I do want to stick with my Dana 30 and Dana 35. I'm not running big tires or power.

*I tend to blabber, so you can skip to the TL;DR now if you want lol*

I currently have my first TJ (third Jeep-XJ convert :p).

PO took immaculate care of it and, mechanically, it is fantastic. Except it has the stock 3.07 gearing with the LP Dana 30/Dana 35 combo. No abs.

Anyway, the PO put brand new 32" Duratracs on it, which are perfect for my needs (road driving to work and then light to semi moderate wheeling a few times a year), so I want to keep the tires.

BUT, the 3.07s are a MASSIVE pain. My short commute is on the interstate for about 20 miles a day. Plus the 3.07s are a complete dog in city driving. The only time I find the gearing adequate is on the trails in 4Lo, but that's different.

My dad and a friend both have manual 4.0 TJs, 32s ans 33s, and they used 4.10 gearing and I really like the way it feels. Much easier to live with. **And they definitely get better mpg than me**

Ok, so my list of parts (ignoring any possibility of adding trutrac, LSD, or any lockers for the sake of this conversation):

Here's what I've ordered so far. If someone could confirm that I'm on the right track or point out anything else I'll need for the install (I'm having someone do it. I can do a lot of stuff, but gears are not something I'm comfortable with).

Some parts don't match brands, because I shopped around for the best prices.

Dana 30:
1. New Spicer carrier since I have the 3.07 carrier.
2. 4.10 ring and pinion gears.
3. RC Dana 30 master install kit.

Dana 35:
1. New Yukon carrier since I have the 3.07 carrier.
2. 4.10 ring and pinion gears.
3. RC Dana 35 master install kit.

*Tl;DR: 99 TJ 4.0 5spd going from stock 3.07s to 4.10s. Halp with list of parts I'll need. Thanks :)
Thanks in advance for the help! I'm a gearing noob. This is the first time I've had to change them.*

** have gone through and replaced and/or upgraded any and all fluids, intake/exhaust/ignition/fuel delivery components, so I know it is all in good working order.**
 
Are you doing this gear swap, a friend or a shop ?
A lot of shops do not want parts brought to them; they want to source the parts.
You will need a gallon of 75W/90 gear lube and at least one tube of RTV.
 
I wouldn't worry about ordering the parts. Just find a reputable shop and have them install the gears that they warranty. Your other option is to find a set of 4.10 axles at a junkyard. Dana 35 should be dirt cheap. The Dana 30's sell for a little more.
 
CharlesHS said:
Are you doing this gear swap, a friend or a shop ?
A lot of shops do not want parts brought to them; they want to source the parts.
You will need a gallon of 75W/90 gear lube and at least one tube of RTV.
Click to expand...
I work in the parts industry. I personally know most of the shops I sell parts to, so that's not an issue, thankfully.
But thanks for the advise!
 
06lj said:
I wouldn't worry about ordering the parts. Just find a reputable shop and have them install the gears that they warranty. Your other option is to find a set of 4.10 axles at a junkyard. Dana 35 should be dirt cheap. The Dana 30's sell for a little more.
Click to expand...
I have tried to keep my eye open for some 4.10 D30s or Dana 35, but no such luck :(
 
I swapped in a set of 4 cylinder axles on an old Jeep. $250-300 for the set. Much cheaper than regearing if you're keeping a Dana 35.
 
If you're going to swap gears...I would highly recommend 4.56 gears and possibly consider 4.88's..but for this conversation let's stay wuth 4.56's

Anything....and I repeat anything is better than 3.07's (even a schwinn 10 speed in 10th gear up a hill)
Joking aside the three O sevens are indeed pathetic.

You've got 32" tires and want to keep them and that's why I recommend 4.56 at a minimum.
You can live with 4.10's and 32's but since you're changing gears why not make it even better with 4.56's?

Your mileage won't suffer. (Negligible if anything)

Food for thought.
Ask any Rubicon owner who has stock 31" tires with 4.10 gears what they'd think if it had a tad lower. (Higher numerically)

You can look at all the gear charts you like but they don't factor in extra weight and rolling resistance of bigger tires.

4.10's and 31's are absolutely the bare minimum.
You've got 32's...committed in your brain to swap gears...(it's not a cheap or painless if doing yourself endeavor) do it right the first time...don't under gear!! 4.56 is the minimum I'd recommend.

I own a shop and you will be further ahead allowing a reputable place to get the parts for you. Out of respect if you've got a nice relationship with them they'll give you deal on the total sum job regardless...and respect for them allowing them to source the parts.

Example...we just repaired the entire braking system on an Escalade. The customer works at a parts house 10 years and counting. At first he thought he'll get the parts cheaper. I said you might want to check that out but it's going to cost you more.
We do so much volume with some vendors I actually get product lower than he can purchase them for from his very employer...one of the vendors I was referring to.

As a shop it's much easier to just get the parts needed. We know exactly what works best and where to source them. There is no surprises. No delays. No missing pieces...no wrong part #'s...etc.
Any warranty issues arise it's all on the garage rather than partially the garage...then back to you...then back to the garage.
Shop's do NOT like that Mickey Mouse horseshit.

As I said if you've a good relationship with some...I'm sure they'll give you a deal somewhere in the sum of it all. Example..if a $1,000 is a good deal to you who cares how they get there. If they charge you more for parts than you can get them but give you a deal on labor...in the end your focus needs to be on the total. Who cares how they got there.

Just some food for thought. Good luck.
 
Rubicon88 said:
If you're going to swap gears...I would highly recommend 4.56 gears and possibly consider 4.88's..but for this conversation let's stay wuth 4.56's

Anything....and I repeat anything is better than 3.07's (even a schwinn 10 speed in 10th gear up a hill)
Joking aside the three O sevens are indeed pathetic.

You've got 32" tires and want to keep them and that's why I recommend 4.56 at a minimum.
You can live with 4.10's and 32's but since you're changing gears why not make it even better with 4.56's?

Your mileage won't suffer. (Negligible if anything)

Food for thought.
Ask any Rubicon owner who has stock 31" tires with 4.10 gears what they'd think if it had a tad lower. (Higher numerically)

You can look at all the gear charts you like but they don't factor in extra weight and rolling resistance of bigger tires.

4.10's and 31's are absolutely the bare minimum.
You've got 32's...committed in your brain to swap gears...(it's not a cheap or painless if doing yourself endeavor) do it right the first time...don't under gear!! 4.56 is the minimum I'd recommend.

I own a shop and you will be further ahead allowing a reputable place to get the parts for you. Out of respect if you've got a nice relationship with them they'll give you deal on the total sum job regardless...and respect for them allowing them to source the parts.

Example...we just repaired the entire braking system on an Escalade. The customer works at a parts house 10 years and counting. At first he thought he'll get the parts cheaper. I said you might want to check that out but it's going to cost you more.
We do so much volume with some vendors I actually get product lower than he can purchase them for from his very employer...one of the vendors I was referring to.

As a shop it's much easier to just get the parts needed. We know exactly what works best and where to source them. There is no surprises. No delays. No missing pieces...no wrong part #'s...etc.
Any warranty issues arise it's all on the garage rather than partially the garage...then back to you...then back to the garage.
Shop's do NOT like that Mickey Mouse horseshit.

As I said if you've a good relationship with some...I'm sure they'll give you a deal somewhere in the sum of it all. Example..if a $1,000 is a good deal to you who cares how they get there. If they charge you more for parts than you can get them but give you a deal on labor...in the end your focus needs to be on the total. Who cares how they got there.

Just some food for thought. Good luck.
Click to expand...
Thank you. You make some good points and I will have to reevaluate my plan now!
 
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