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Joshpfeffer 02-28-2009 02:35 AM

Axle Upgrade With Lift?
Hey, I've been searching around a lot, and can't seem to find anything on this, but I'm sure it's been discussed before, so I apologize ahead of time for the repetition, but:
I'm looking into the 4.5" Rubicon Express Super-Flex lift with the SYE and CV Driveshaft, along with a 1" body lift. According to RE's website, a 35 x 12.5 tire is perfectly fine, but it seems to me that I've read something about upgrading your axles when you start to push your tire size up like that. Is that right, or is my memory failing me? Being fairly new to the Jeep scene, would someone mind taking the time to really explain this all to me? With certain sized lifts, what supporting modifications will you need for everything to work correctly? I've read small bits and pieces about transfer case drops (most of which seem to be bashing this idea), this axle upgrade stuff, upgraded steering boxes to coincide with lifts, motor mount lifts, steering stabilizers, etc. So I guess what I'm really wondering here is, as you continue to lift your Jeep, and add larger tires, what other modifications will you need to make, and at what height will the modifications need to be made? Thank you in advance for any help you can offer me.
And if it will help in you advising me personally, this is for a '98 TJ, and I don't plan on any sort of competition level rock crawling or anything. I live in Missouri, and just want to be able to overcome just about any trail, embankment, and mud pit I might come up against around here. From what I've read, long arm suspension lifts and things of that sort won't really be necessary, right? Thanks again.

stevens243 02-28-2009 02:56 AM

For the axle's, it's not the lift, but rather the tires you slap on there after you lift it.

So, what axle's do you have now? What size tires do you want to run? Those questions will help answer what size lift to go with and what type, which in turn, will drive the T-case/SYE CV/MML questions you have as some lifts make them required and some lifts make those upgrades not upgrades at all.

As it seems you are really looking to mud the jeep, getting some clearance is critical as no brake works better than a front differential plowing thru the goop.

Joshpfeffer 02-28-2009 03:12 AM

It's all stock as it sits now. It has the 4.0 in it, manual. Beyond that, I'm not sure on the axles. I'm planning on the 4.5 Super Flex from Rubicon Express, along with a 1" body lift if I can straighten out my knowledge of everything first. I don't want to get everything installed, then have some issue that I hadn't planned for. When I do the lift, it'll get wheels and tires as well. 35 x 12.5, on a 15x8 or 8.5 wheel is what I have in mind.

4Jeepn 02-28-2009 08:04 AM

1st. Go out to your jeep and look at the rear axle. If it has a metal drain plug in the cover, congrats you just saved yourself about $1000 to the over all build price. If it has a plastic plug in the cover, add an extra $1000 to the list. The plastic plug is the sign of the Dana 35 axle, its weak and does not like big tires, low gears and don't even think about a locker back there with 35's.

Good news is you can swap in a Dana 44 (metal plug) or upgrade the dana 35 to stronger shafts. But you can look into that debate on your own.

Tires. 35's tires are big and heavy. The stock steering box is about at its limit with 35's. The front axle will live, but make sure your ball joints are in good shape and axle shaft u-joint too.

You will want to upgrade the drag link and tie rod. Currie makes a very nice setup.

As for stopping your stock system will work, but it will be taxed. A future upgrade in this area is something to consider.

You do not need to lower the T-case skid if you have an SYE installed.

I ran the RE 4.5 kit on two of my TJ's. one with 33's and one with 35's. Nice kit, make sure you keep it greased!

One other thing to consider is a gear change with the 35's I will guess you have 3.07's-3.73's for 35's 4.56 or 4.88 work well, but don't spend money till your sure what you want out of it.

Hope that helps a bit.

Joshpfeffer 02-28-2009 12:23 PM

So, as long as you do the SYE along with the lift, no T-Case drop is needed? Rubicon Express includes the t-drop with their 3.5 Superflex, but also recommends the SYE. This is confusing me as to what is actually needed, and what's not.

DLWilson 02-28-2009 12:43 PM

The t-drop won't be needed if you SYE.

here's a good thread about building for 35's..

Want to run 35's?

Cryptos 03-01-2009 12:38 AM

Ive got the RE Superflex 4.5 and a body lift with a dana 35 lock right rear w/ 4.56 and 35" bfg mt's, no complaints once so ever...

MoA 03-01-2009 10:30 PM

you can run 35s on a dana 35.. heck my gfs jeep has it.. but than again she isnt a hardcore wheeler.. it depends on the terrain you ride and also if you got a locker or not.. if its mainly a dd and sees light trail use then a d35 will hold up.. it will break easier but if you take it slow (like you should) then you shouldnt put too much stress on it..

its when you get ballsy and open up the throttle or try to power out of something that you can start breaking shafts..

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