AXLE SWAP OPTIONS

[FirstTimer]

I was hoping I could get some insight into whether or not it would be less expensive to track down a set of axles with the appropriate gearing to run 33inch tires then it would be to re-gear the current DANA 35 and DANA 30 I have in my 02 Jeep TJ Sport 4.0L?  Additionally, what would my options be for a swap that was basically bolt in, if in fact I did find a set of axles that were geared right?

Currently, I have sourced out a couple of options.
1.  Swapping out my axles for a members axles who is running 4.10 gearing on his dana 35 and 30 as he is upgrading to ford 8inch axles.
2. 98 zj dana 35 and 30 3.55 gearing with coils and disc brakes front and back (will this even fit?)
3. your suggestions.

Keep in mind this is my DD driver and I am not an Uber wheeler, this summer will be my first summer wheeling. So I intend to be light on the gas and will be running less aggressive MT tires.
THANKS!!!!

[WhiteOut]

Swapping the TJ axles with 4:10s is going to be the easiest. The rear ZJ axle will not be a direct bolt it for the TJ. I assume you have 3.07 gears now?

[FirstTimer]

3.07 is indeed what I have! 
How much power will I lose if I go to a 4.10 ratio, as I've heard 3.56 is best?

[BlackAura]

Someone correct me if I'm wrong, but I believe (with a higher gearing) you will be getting more power transferred to the wheels at a loss of some top speed.

Swapping in larger tires will then balance this somewhat.  One tire revolution = you move one circumference of distance, so with a larger tire, you go further.  Higher top speed at a loss of torque.  Also larger tires = heavier, so a little more of your engine's power goes to rotating them, and less power makes it to the road.

Also (you didn't mention this, so just in case), your speedometer will be out if you don't replace the speedometer gear in your transfer case.
(Check that for your year, I know the 2003s and higher could have some ECU parameter adjusted by the dealership to fix the speedometer)

There are some good charts out there to match up which speedometer gear you need for your tire size, and your gearing:
http://www.raingler.com/tech/speedoChart.asp

[Jrama]

You always gear lower, numerically higher, to compensate for larger diameter tires.

 If you swapped in axles with4.10's it wouldn't be bad at all on the road with 33" tires. You would be slightly more fuel effecient as your highway revs will be lower than factory. I currently run 3.73 and its ok but i hope to re gear soon

overall your ideal ratio depends what transmission you have
5 spd -you would re-gear to 4.56 for 33" tires, if your not wheelin it alot maybe even 4.10 would be ideal
Auto- 4.10 is ideal

If your running 33" tires your best bet is to get rid of your d35 and find something stronger,  by stronger I also mean signifigantly more expensive. Again if you drive it on the road more and wheel it lightly, just sticking with d35 would be ok, certainly not ideal. D35's fail on a regular basis. If it stays just on the road go with 4.10 d30/d35 combo

[BlackAura]

You always gear lower, numerically higher, to compensate for larger diameter tires.

Errr, good point Jrama.

I should rephrase:

Someone correct me if I'm wrong, but I believe (with a higher gearing) you will be getting more power transferred to the wheels at a loss of some top speed.

to:

Someone correct me if I'm wrong, but I believe (with a higher gear ratio) you will be getting more power transferred to the wheels at a loss of some top speed.

[Spinalguy]

rubicons came with 4.10's and 31's as a TJ. With a 5 speed tranny, that was good. With Auto it was not good enough.
If Auto, you need higher ratio number, with manual tranny, slightly less.

35's and Auto are dialed in with 5.13.
37's and manual are dialed in with 5.13.

4.88 is the lowest NUMBER i would go if i was running 33 or 35.

[Spinalguy]

Oh, i would not buy axles that were 30/35 combo for any reason. You would be better building your own 30/35 with gears and stronger axle shafts.

[Raspberry]

+1 for not throwing money at a D35 rear axle. It severely limits your other choices, like how big of a tire you can go, whether or not to install a locker in the diff, and how much trail abuse it can take before breaking.

If you want I may soon be selling a Chrysler 8.25" rear axle from an XJ with 3.55 gearing.

[w squared]

4.10's were great with my SIX speed and 32's. 4.10's are just okay with my SIX speed and 35's....but I'd be happier with 4.88's or 5.13's.

Don't bother spending money on a half-arsed solution. If you're going to spend money, spend money on what you really want...not on something that's kinda sorta maybe what you want. If you want 33's and don't have a fancy-dancy 4:1 transfer case, shorter gears are better

[Jrama]

rubicons came with 4.10's and 31's as a TJ. With a 5 speed tranny, that was good. With Auto it was not good enough.
If Auto, you need higher ratio number, with manual tranny, slightly less.

35's and Auto are dialed in with 5.13.
37's and manual are dialed in with 5.13.

4.88 is the lowest NUMBER i would go if i was running 33 or 35.

Interesting, I was thinking of going to the popularly suggested 4.56 ratio for my 33" tires which will be replaced by 35" in due time. Either way this little calculator helps you work things out. As for my numbers with the auto trans, those were the popular opinions I came across browsing through JF. I think i may reconsider and go to 4.88

http://www.manoian.net/jeep/gear_ratio_calculator.html
Trans=Nv3550
4.88 and 33" tires places 110 kph at near to 2700 rpm
4.56 and 33" tires places 110kph at near 2500 rpm
4.10 and 33" tires places 110kph at 2200 rpm
3.73 and 33" tires puts you near 2000 rpm
I wasn't really too intent on regearing till I drove a jeep with 4.88 gears on 35's and realized how terrible my jeep was in comparison.

[FirstTimer]

To clarify a few of my jeep specs, it is a five speed manual, 4.0 L 6cylinder with the np 231 t-case.
The axle option I would consider buying from one of the members although it is a 30 35 combo, it is much less then regearing my current 30 35 combo, leaving me money to maybe truss the axles or turn the 35 into a super 35...any thoughts? additionally to be honest I am looking for the simplest solution as I don't want to pay someone out the butt to fab in some crazy strong axle combo that I wont truly need...for now...
are there any dana 44 options that will bolt right in?

[Spinalguy]

i hear ya.
i drove mine with 4.10's and 37's and swore it was ok. But as soon as i went 5.13, i realized how not ok 4.10's were. lol.

[Vinman]

35's and Auto are dialed in with 5.13.

This is what I had on my 2003 Rubicon and it was a PERFECT combination. About 2,500 RPM at 110k which put it in the perfect range to make power.

It also gave me the BEST gas mileage ever in that Jeep, better than stock, better than 4.10's with 33"s and better than 4,10's with 35"s.

Vince

[cLAY]

How cheap are the axles, what sort of shape are they in and do you plan on ever going bigger than 33" tire, do you want to keep the stock ABS?

There's nothing wrong with going to a rear d35  if staying 33" and under, lots of bolt on upgrades to make it comparable to a D44 without the hassle of getting new mounts put on and you can build it in stages to offset the cost. Now if the axle is in poor shape and needs a rebuild anyway you may be better off finding a TJ D44 rear and having it regeared. I don't think the standard TJ D44 came with 4.10s from the factory(correct me if I'm wrong), except the Rubicon which is big bucks and hard to find used. 

Anything NOT out of a TJ will require a fair bit of fabbing to fit(including a ZJ axle).

4.10s is good with 33s if doing lots of street driving, 4.56s with 33s are better offroad but run a higher RPM on the highway and can hurt fuel economy.

If you think you might go bigger than 33" then bite the bullet now and spend some coin on a HD rear end.

Also consider that the brakes on a D30/D35 combo are marginal at best with 33"  tires.