On the 4dr JK, what is the max lift you can do before you need any driveline mods?

I do some wheeling, but not enough to justify new shafts yet. I know on the 2dr JK, you can go to about 3" before needing new shafts.

 

I've been trying to find this out as well. I've seen people say 4" is ok...then again I've read about people having trouble at 3.5". I'm doing a 2" BB lift on mine and maybe a 1" body lift. That's it.

 

I can only speak from experience. I put in a 3" Black Diamond lift on my 4d Rubi. Here's what everyone forgets to mention. Many lifts also take the "rake" out of the Jeep, where the factory front is lower than the back. In the case of my lift, the front went up 4 5/8", the back 2", and exactly 3" at the front door sill. Even after putting on my bumpers there was still 4" in front and 2 1/4" in rear (also took off the hard top - back end went UP even with the new, heavier bumper).

OK, the punch line. Under full flex the front drive shaft made contact with the automatic transmission pan and ripped the boot. Turns out this is a very common problem with lifts of any length (do a search on this forum to see for yourself). While some had a new drive shaft replaced under warranty, and others found a way to put on a new boot, I couldn't justify worrying about when the next time I'll flex the front enough to rip the boot. A new drive shaft was the only answer for me.

This happened with a 2008 Rubicon with the front swaybar disconnected. If you don't plan to have disconnects and/or have a manual transmission, then maybe you are OK. Read some of the threads to see what setups others had when they experienced drive shaft problems.

The other area I've read where the drive shaft was damaged was on the stock automatic transmission skid pan. I took the precaution of grinding it down some and lowering it a bit. Looks to have more than enough clearance.

 

You'll be fine with your unlimited at 3" and 35's with no driveline mods

 

You can go up to a 4" lift on the 4dr. The rear drive shaft angle is fine but the front is at its max on a manual trans. JK's with auto trans run into problems like AZJeepr said. Drive shaft boots on the front will get caught up on the trans and tear. Manual trans this doesn't happen but the angle of the shaft is worse than an auto trans. On the auto trans kits they have trans/tranfer case lowering brackets which decreases the shaft angle but on the manual trans you cant lower the trans. All the gear oil would migrate to the rear and no oil up front which would cause tranny damage.

 

This isn't accurate. Lowering the trans/transfer case would worsen the angle at the front of the case. The spacers included in some kits lower the tranny skid, NOT THE ACTUAL TRANS/TRANSFER CASE.

 

4" on an Unlimited manual and you will probably have to notch the skid for the front shaft on an Automatic. I have a Skyjacker 4" on mine 4 door and no problems but have read of the front shaft boot being ripped off like stated above.

 

I have a 3.5" kit+1" bl with 35's and wheel every weekend with stock driveline, I have yet to have a problem (knock on wood).

 

Even the smaller lifts will cause the CV-style OEM drive shaft joints to wear faster due to the increased angles. There's really nothing you can do about it - the greater the angle, the more wear. I'll run mine until I can feel play in the joints and then replace them with some real drive shafts that will stand up to the increased angles and offroad use.

 

Yup. I plan on the same, run em til they crap out, then replace them with some Tom Woods shafts.