Need some help planning out my axle set ups.

The Jeep: 97 XJ. 220k on the clock. 6.5" lift. 33" Duratracs. D30 front (no idea on spline count) and a D35 in the rear. 4.0, automatic, 3.55 gears.


The plan: Trashing the D35 and going with either an 8.25 or an 8.8 depending on what I can find at the junkyard. Also my Duratracs have about ~50k on them and I'll need new rubber soon enough and I'll be going to 35s.

Driving Environment: This jeep is my DD and will remain my DD for at least another year. Lots of highway miles. I drive about 80 miles a day on the hwy when I'm on duty. While it is my DD I also use it to play a little bit, and I have plans to retire the jeep to toy/winter beater status in a year or so.

I am a flatlander. I live in the midwest. Nothing to climb to speak of. Sandy minimum maintenance roads, mud/mudholes, and snow/ice are the "offroad" environment it will see. Nothing extreme. I am willing to suffer a bit on the DD manners until the the jeep "retires" to achieve better results during playtime.

What I need help with:
Trying to figure out what I should do in terms of locker/posi set ups for each axle based on my driving environment. I still need it to be streetable, wife will drive it in the winter. Not sure if this rules out lunchbox lockers or not. I have been doing a lot of reading about this here and if I'm understanding correctly, a lunchbox in the front will not make a lot of ratcheting noise or cause any steering issues at all until the jeep is put into 4wd correct?

Since it won't be an offroad monster, I was thinking of putting a lunchbox in the front and a truetrac in the rear.

Guide me. Is this a bad idea for my driving environment? Overkill? I don't need or want anything crazy, but I want to be able to get out whatever trouble I can get myself in. I have also played around with the idea of selectable lockers (cable or electronic) front or back, limited slip in both front and back, etc. I really have no idea how to proceed from here.

If I had to pick a "priority" I would pick snow/ice performance. I really need it to excel in the winter months.

I vote Trutracs front and rear with an 8.8 in the rear. This is the setup I run, I know you guys don't get as much snow as us here in Northern California, but the Trutracs work great in the snow AND the rocks/mud. Lunchbox and auto lockers are a terrible idea on the snow. The Trutrac is high bias, I know people just call it a limited slip but I know people who have run them through the Rubicon with no issues. Maybe a tad excessive wheel spin every now and then while in the rocks but it makes up for it by being extremely street able and predictable in the snow.

you will want to regear to 4.56 or 4.88, thats for certain.

as for lockers... you wont regret selectables if you can swing the coin.

It depends on your budget. If you can find a Dana 44 out of an XJ it will have 4:10 gears and bolt in with no welding needed. Keep the D30 and swap in 4:10 gears and a True Tack. The auburn ected is a limited slip and locker in one maybe that would be a good choice for the rear not sure though I have no experience with the ected.

From my experience, a good limited slip will lock both tires just as fast as a locker in the snow if the tires slip at all. To me it's not much different of a driving style. Just an idea to keep in mind.

33"s, with 4.11 gears, wiill not be much fun to drive.
35"s will be worse.
Go with 4.88 gears.

lazyxj said:

33"s, with 4.11 gears, wiill not be much fun to drive.
35"s will be worse.
Go with 4.88 gears.

Click to expand...

:wierd:

I have 33's now and run 3.55s. Its not bad at all. I still have plenty of power to pass, and I get 17-18mpg highway with a 6.5" lift and 33s.


I've been looking at gear ratio charts today after reading your post and I can't seem to figure out how they would be relevant without knowing which transmission the power is coming from...

Rotorhead84 said:

:wierd:

I have 33's now and run 3.55s. Its not bad at all. I still have plenty of power to pass, and I get 17-18mpg highway with a 6.5" lift and 33s.


I've been looking at gear ratio charts today after reading your post and I can't seem to figure out how they would be relevant without knowing which transmission the power is coming from...

Click to expand...

gearing charts are typically based on RPM. for most jeeps, the gearing chart is relevant. displacement plays a part, but most jeeps are lacking.

you may think its ok, but its relative. get in a hilly area and your trans will be working overtime. drive a geared jeep and report back.

I have 4:10 gears with 33's and would like to have 4.88 or even 5.13. With camping gear, tools and spare parts my jeep has a hard time on grades.

Rotorhead84 said:

:wierd:
I have 33's now and run 3.55s. Its not bad at all. I still have plenty of power to pass, and I get 17-18mpg highway with a 6.5" lift and 33s.

Click to expand...

Guess you have not spent much time in Colorado.
Going just about anywhere in the West involves going up or down long, steep grades. Deep gears are good.

Whatever ratio you go with, adding a pair of Truetracs is a good choice for something your wife will be driving in the winter. Effective and nearly invisible.

VAhasnoWAVES said:

gearing charts are typically based on RPM. for most jeeps, the gearing chart is relevant. displacement plays a part, but most jeeps are lacking.

you may think its ok, but its relative. get in a hilly area and your trans will be working overtime. drive a geared jeep and report back.

Click to expand...

I found a gearing chart that takes into consideration the transmission and xfer case. Pretty handy.

http://www.grimmjeeper.com/gears.html


You're right about hills for sure. I live in Nebraska where it is relatively flat. But I'd driven this jeep back and forth to the east coast about 10 times and when I hit the hills/mountains, I basically have to stay in 3rd most of the time on the uphill side.

lazyxj said:

Guess you have not spent much time in Colorado.
Going just about anywhere in the West involves going up or down long, steep grades. Deep gears are good.

Whatever ratio you go with, adding a pair of Truetracs is a good choice for something your wife will be driving in the winter. Effective and nearly invisible.

Click to expand...

Spent lots of time in Colorado. Live fairly close, have lots of family there. You're right about hill climbing. I just tend to forget about stuff like that because I am a flat lander and don't spend a lot of time in that environment. if 4.11s aren't going to cut it, I'm open to whatever will serve me best, I just want to keep it on the conservative side for mileage reasons. If 4.11s is too conservative, then maybe 4.56s?

Rotorhead84 said:

if 4.11s aren't going to cut it, I'm open to whatever will serve me best, I just want to keep it on the conservative side for mileage reasons. If 4.11s is too conservative, then maybe 4.56s?

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My XJ has 33"s and 4.56 gears.
It runs at about the same RPM, at 60 MPH, as it did when stock.

Being in CO and running 33's on 4.11's I'll admit it's not the best. If I'm unloaded it's not that bad going up the hill and around down does perfectly fine. But loaded with gear and going up the hill I would rather have 4.88's or at least 4.56's. When I had 31's the 4.11's did awesome, but 4.11's are getting pushed with the 33's. I would recommend a 8.8 in the rear w/ a LSD already in there and then getting a trutrac for the front. If you want to run 35's I would go with 4.88's, 4.56 if you want to be a little more conservative. 4.11's on 35's is just going to leave you wanting more.

For 35's I'd go at least 4.88.

Thanks everyone for the advice so far.

While I love 4.88 on my 33's off road, on the interstate and even around town, it's a bit too deep for gas mileage purposes. 4.56 would have been a perfect compromise, I think for 33's so I bet 4.88 would be just right for 35's.

Rotorhead84 said:

:wierd:

I have 33's now and run 3.55s. Its not bad at all. I still have plenty of power to pass, and I get 17-18mpg highway with a 6.5" lift and 33s.


I've been looking at gear ratio charts today after reading your post and I can't seem to figure out how they would be relevant without knowing which transmission the power is coming from...

Click to expand...

I keep hearing that 3.55's and 33's aren't bad at all, until they regear to 4.56's or 4.88's and wonder why they didn't do the regear years ago. Ask _ANYONE_ who has regeared after driving for some time on 3.55's with 33's. The performance difference is amazing. 4.88's if you think about 35's.

I'd also do selectable lockers, especially in the rear with snow.

On a 33" tire you'll be turning about 2500 rpm at 70mph.

Currently running 33s with 4.56. Pretty nice environment. Will be going to 35s, and staying with 4.56s, but I also have a stroker to make up that difference on highway, and 4:1 to make up for it off road. Without the stroker, I'd suggest 4.88 with 35s. But, do you really want 35s for a mostly DD? the price difference between 33s and 35s might convince you otherwise.

I'd also agree about selectable lockers front and rear. You couldn't pry the ARB lockers out of my cold, dead, fingers.

David Bricker / SYR

just pulled a 8.25 out of my 00 XJ. Make it to Rapid ever?

If you go for the 8.8 try and find an open carrier to begin with, the LS carrier is the weakpoint in that axle a few locals have broke the carrier's on some mild wheeling. Just my .02. like stated earlier I would wait and save up for a Dana 44 from an XJ direct bolt in, no need for a driveshaft adapter and wheel spacers. I paid $250 for mine. Your Dana 30 will be fine though.