Making a Rubicon LJ on 35's Streetable?

[nwoods]

I'm a total newb, so I may be asking a few stupid questions, but I could really use some answers to these basic questions, so if you have some insight, please share it!

I'm about to buy a 2005 Rubicon Unlimited that currently has a Currie 4" lift and 1" body lift and 35" ProComp XTerrian 315/75/16 tires on it. We will be off roading this rig considerably, but we need to drive it to our destinations. Currently, it is pretty sluggish on the side streets we test drove it on and we are not even sure if it can get up to highway speeds.

It has the stock Rubicon gearing with the NV241 Rock-Trac transfer case (4:1 ratio) with Dana 44 axles w/ air-actuated Tru-Lok differentials at I believe a 4.10:1 ratio.

I have also driven a nearly identical rig (same stock driveline) but with 33" MT Baja Claw tires, and it felt much more capable of highway speeds and had significantly more power off the line.

So my question is, if we keep the 35" tires, what is the magic gear ratio that I should be looking at to give it a bit more ooommph on the street and drive at highway speeds? How will this degrade off road performance? (or will it?). From what I've read online, it seems that somewhere between 4.56 and 4.88 is the ideal ratio.

With 35's on it, will it ever drive as well as the jeep with 33's in terms of power/speed range? If I opted for 33" tires in the future, would 4.88 gearing still be okay?

Will the factory lockers complicate changing gears? or is that not affected?

And finally, what is the expected cost range to have the rig re-geared, assuming I have a shop do it (such as John at All4Wheel)?

Thanks for your help!

[Jerry Bransford]

4.88 will be ideal for 35" tires. I'm running that combination and it's a great all-around on/off-road combination. Plan on $1100 or so, plus or minus $100 or so for the entire regear job. The Rubicon's air lockers won't increase the regearing job's complexity by much at all.

[mrchips]

I would bet that a 4.88 gear is going to bring you back to stock performance set-up, with 35's, and if you were to go to a 33 tire I would say a 4.56 gearing would be best you would not really have an issue. More performance if anything, yet a decrease in gas mileage, but I dont think that is an issue if you are running 35's..
I have an 06 LJ Rubicon, and 4.10 and 33's and it is fine for getting to and from trails, and running the freeways however I would like to go to 4.56 to bring it back to stock. Hope this helps.

[nwoods]

I've been reading lots and lots of forums and websites all afternoon, and everything I've read supports exactly what you've been saying, that 4.88 is the way to go on 35's.

Of course, nothing is that simple for me... As this is our first Jeep, 35's are a bit intimidating, and more than likely, overkill for what we will do with the Jeep. I don't envision running out and trying the Hammers or anything. The current tires (ProComp XTerrians are about 40% worn, and will need replacement probably before year end. We've been contemplating going with 33's in the future, as it's a more drivable option and certainly capable. I did many of the trails in Moab on 32's with a rental Rubicon (2 door), and had no problems.

So if I get 33's in the future, maybe I should get the 4.56 gearing now? Or can I run 4.88 with 33's and not blow anything up?

[dadasjp]

I have exactly what you're looking at buying, except mine is a TJ. I have the Currie 4" w/1" body lift and 1" motor mount lift. I run 4.88's w/35's. I've run 33's with both the 4.10's and 4.88's. 33's with 4.88s are doable, just take a bit getting used to, the 35's are great with the 4.88's. I run an auto, no problems. The lift also works very well, nice and smooth. I have done the air-intake, exhaust and hypertech upgrades to add a bit of power, probably about 20-30 hp total; all she needed. She's not a street rod, but climbs like a goat and has no problem doin' 70 down the freeway. Go see the guys at T&J Performance in Orange, they did the power upgrades and gears for me, great job no problems. They also race Jeeps, they know what they're doing. Ask for Jake. Remember to follow the break-in instructions for the gears. You might also want to look at axle shaft upgrades if you're going to run hard; I went chromoly for the upgrade to 35's. You might want to get this done along with the gears. Just my two cents. Happy wheelin'.

[Lawrence]

I've been reading lots and lots of forums and websites all afternoon, and everything I've read supports exactly what you've been saying, that 4.88 is the way to go on 35's.

Of course, nothing is that simple for me... As this is our first Jeep, 35's are a bit intimidating, and more than likely, overkill for what we will do with the Jeep. I don't envision running out and trying the Hammers or anything. The current tires (ProComp XTerrians are about 40% worn, and will need replacement probably before year end. We've been contemplating going with 33's in the future, as it's a more drivable option and certainly capable. I did many of the trails in Moab on 32's with a rental Rubicon (2 door), and had no problems.

So if I get 33's in the future, maybe I should get the 4.56 gearing now? Or can I run 4.88 with 33's and not blow anything up?

5.13 would be perfect with the 35s. Keep in mind that 35s open other issues such as steering, brakes, etc... Some rigs are more affected than others, so make sure it is up to par.

If you plan on going to 33s in the future, go with 4.88s. I had 35s and 4.88s (4-speed auto) for nearly 2 years, and it was fine for most cases, but it kept downshifting on long grades. I recently redid my suspension and returned to 33s, and the 4.88s are simply amazing. It pulls very nicely, even on grades where I had to kick the OD off with the 35s, it nows gets up and go.

The 4.0L is happier at higher rpms than most vehicles, and the 4.88/33s combo will put you in that sweet spot. You won't blow up anything. Here are my rpms with that combo:

OD ON
60 mph Speedo - 57 mph GPS - 2,000 rpms
65 mph Speedo - 62 mph GPS - 2,250 rpms
70 mph Speedo - 67 mph GPS - 2,350 rpms
75 mph Speedo - 71 mph GPS - 2,500 rpms
80 mph Speedo - 76 mph GPS - 2,650 rpms

OD OFF
60 mph Speedo - 58 mph GPS - 2,900 rpms
65 mph Speedo - 62 mph GPS - 3,150 rpms
70 mph Speedo - 68 mph GPS - 3,350 rpms
75 mph Speedo - 71 mph GPS - 3,650 rpms

BTW, good choice on leaning towards that white one, I think it is the better setup of the two. If you want to drive my rig to get an idea, PM me. I have 33s Pro Comp Xtreme MT, 4.88, 4-speed auto, currie 4" lift....

4.88 will be ideal for 35" tires. I'm running that combination and it's a great all-around on/off-road combination. Plan on $1100 or so, plus or minus $100 or so for the entire regear job. The Rubicon's air lockers won't increase the regearing job's complexity by much at all.

Right Jerry, but you have the 3-speed and not the 4-speed auto.

[nwoods]

Lawrence, thanks for the detailed info, that is very reassuring to see that the 4.88's will suffice as a decent all-around gear ratio. Gives me piece of mind that I won't be pulling them out and paying for it twice in the near future.

Last night my family voted and the White LJ gets the nod. It's just too cool, with some thoughtful modifications (front and rear air connections to a Viair 450 and 2 gal tank, brake light plug interface socket mounted near the winch control socket for easy towbar hookup, Currie Anti-rock pneumatically disconnected swaybars, Magellan 540c hardmounted, iPod interface controllable through a new Alpine headunit, waterproof seat covers, tummy tuck and skids from Terraflex, siders, swing-away tire rack, etc... The White truck is built to be used, and if he accepts our offer, we will use it accordingly!

And most importantly, my wife likes it!







Also, if anyone is looking for an IMMACULATELY clean 2006 Silver Rubicon Unlimited, check this out:

[womb raider 940]

wow an LJ with no top looks weird.

[Jerry Bransford]

Hubba hubba, nice!! And so is the Jeep!

[Lawrence]

Lawrence, thanks for the detailed info, that is very reassuring to see that the 4.88's will suffice as a decent all-around gear ratio. Gives me piece of mind that I won't be pulling them out and paying for it twice in the near future.

No problem... Just remember that the rig is now much heavier than stock, so you have to compensate for that and “getting back to stock” is not good enough.

When I bought my Jeep, it had 35s and 3.73s, it was so bad a snail could beat me off the line. I went with 4.88s (lowest available for D30) and I suddenly thought my TJ was a sports car. Then, after driving it for nearly 2 years and seeing its road manners, I had a choice to make. Keep the 35s, find a Rubi 44, and go with 5.13s… Or keep it the same and ditch the 35s for some 33s. My wife wanted to keep the big tires, but after many conversations and key phrases such as "You look nice today honey... BTW, about the tires, I was thinking that [...fill in the blanks...]", I was able to convince her to go with 33s, and I couldn’t be happier for a lot of reasons.

4.88s will be good all around, but if you are set on keeping the 35s, I think that 5.13s would be much better. Where you'll appreciate it the most will be on those long grades. With my wife and daughter, a cooler, and some additional fluff items, my TJ doesn’t “strain” as much when heading out. It makes the drive to the trail head that much more pleasant. I can also accelerate nicely to get out of harm’s way, and it is a lot of fun on city streets.

Edit: Most of us giving you advice drive TJs, but I believe the LJ is slightly heavier, so again, you need to factor that in. The best you can do is to get the Jeep and see what you like and dislike about it. Then, hook up with some folks and drive various setups to get a feel for what you want to end up with.

[Lawrence]

Hubba hubba, nice!! And so is the Jeep!

Jerry - I think it is time you make reservations at the Sandals Resorts.

[WSTN Saga]

Glad to see this discussion. I currently am running
35's with the original 4.10's gears. It is really a pain to drive daily. I am also looking to upgrading to 4.88's and chromoly shafts. How much should I expect to pay for Parts and Labor? I saw $1100 earlier but I think that is without the shafts.

[nwoods]

I called John at All4Wheel (951) 277-1037. He quoted me "About $1500, done right" I believed him :-)

[Lawrence]

I called John at All4Wheel (951) 277-1037. He quoted me "About $1500, done right" I believed him :-)

John Lemieux is probably THE best guy in SoCal for gears and lockers. He has done mine twice and I never had a problem. He has also done most of my friends, and nobody I know ever had a problem. He will also stand behind his work should you have a problem. Some may be a few $$ cheaper, but none are as good as John. Good choice on the shop selection.

So???? Did you get the white one????

[nwoods]

So???? Did you get the white one????

Yes, I think so. I agreed to the counter offer, but as i was sending him the message, my company started implementing a layoff plan. If I have a job tommroow, I will buy it. If I buy and then get laid off, I'll go wheeling :-)