Just installed my RK 3.5 X Factor on my 2dr Rubi 6 spd. I thought because of the info in the FAQs I would be ok leaving the front stock DS but it seems if I plan to wheel, and flex out my rig I will be ripping the DS boot on the exhaust. I have extended the front upper control arms to help give me a little more room inbetween the boot and the exhaust.
Any suggestions other than replacing the fromt DS? Just didn't think I would need to do the front.
Please see last sentence below.


This is copied and pasted from the FAQs:

Q: Are new driveshafts needed after installing a lift?
A: You really should consider installing a new rear double cardin U-joint style drive shaft if you have lifted your Jeep JK Wrangler 3" or more and have a 2-door. This is needed because the short rear drive shaft of the 2-doors will be at a steep enough angle that the CV boots will wear out prematurely. However, in order to do this, you will need to buy a set of rear adjustable upper control arms so that you can properly set your pinion angle. 4-Door Unlimited models do not have this problem as their rear drive shafts are very long and a lift will not effect the angle of it too much. As far as the front goes, if you have an automatic transmission, you will need to replace the drive shaft with a double cardin U-joint style unit as well as the diameter of aftermarket shafts will be considerably narrower and will not come into contact with the transmission and/or skid plate. Failure to do this will result in the tearing of the factory drive shaft boot as it makes contact with the transmission. Manual transmissions will not have this problem and keeping the factory front drive shaft will not be a problem.

 

anything above 3 inches of lift put you in the drive shaft replacement zone. offroading will just increase your risk. so yes u will most likely need one.

 

It depends on how much droop your shocks allow. If you are running front shocks over 27" extended then you are in the danger zone of hitting the exhaust. It's easy to check, just pit the front of your jeep on jackstands and lower the axle and see if it hits.

FYI, There is another option besides a new driveshaft, but it seems less popular...

I have a 6 speed and when I installed bilsteins with 27"+ extended length I could see the ds hit the exhaust on the lift. I installed the AEV LCA drop brackets and I now have about 1/2" clearance at full droop. The drop brackets change the geometry so that the pinion tilts upwards as the axle drops, gaining a bit of clearance for the driveshaft at the crossover. Based on my install I would say this is a viable option for pre-2012 jeeps with 6speed and less than 28" extended shocks. (Not sure about the 2012 exhaust.)

 

If it helps, I ran the RK 3.5 with the stock front driveshaft for almost 50k miles. I ordered a Coast last week.

 

Yes that does help, do you have any idea what length your running your front control arms?

 

You can however, get that same black strip of grease just from the CV boot squishing the excess grease out from having to conform to the new angle. This happened on mine and I got a line grease that squirted out, but the boot is in fact not damaged or cracked.

 

With the 3.5 rk, you basically have a 4in lift.........

Also from FAQ.....................




Q: What are all the components that I will need with a 4" lift?
A: For a 4" lift, you should have a set of 4" coils, bump stop extensions, longer shocks, extended brake lines, longer sway bar links, adjustable front track bar, adjustable rear track bar, front and rear track bar relocation brackets, dropped pitman arm, adjustable upper and lower control arms front and rear and new double cardin u-joint style drive shafts.


Personally, get the rear first on a 2dr and just run the front as long as it's still good.

 

I don't know the lengths off hand, but they were almost exactly what RK recommended in the instructions. As close as we could get.

 

Well I've figured it out a bit, and your right about it not being a 3.5in lift. (which I knew it would be bigger) but... its not near 4 either...
Just measured 5.75 in the front and 5.5 in the rear!!!!
Yup, thats right!
So.... that is why I was thrown off. And also why Ill prob be needing new drive shafts
3.5in lift..

 

Figured as much, generally alot of the so-called 3 and 4in lifts give 5- 6in of actual lift. Some settling will occur and the more weight,bumpers,winch,spare tire, gear,armor,rails,etc , the more it'll drop. Some of them don't drop alot though, haha.