Super-Flex2 Adjustable Rear Upper Control Arms
When you lift your Jeep at least three or more inches (or install a raised tcase skid plate like I did), you will want to consider a way to adjust your rear axle pinion angle. When it comes down to adjusting the rear pinion angle, you have two choices:
- Degree Cam Bolts, $40 (Rubicon Express p/n RE1475).
- Adjustable Rear Upper Control Arms
While the "Degree Cam Bolts" are inexpensive and get the job done, they are considered [at best] a short cut. At worst, they do not offer the range of adjustability that new arms do. Since I like to do things right the first time, I opted for the RE arms (RE part number RE3783). While several companies make these, I put my trust in Rubicon Express's strong design and great reputation. I got the Super-Flex2 arms instead of rubber bushings because of the slight articulation increase the Super-Flex2 joints add. Above to the right you can see what an adjustable control arm (left) looks like compared to an OEM control arm (right).
The reason behind installing these arms is to correct the harsh driveshaft angle that is incurred by lifting your Jeep. These bad angles can: cause bad vibrations, ruin u-joints, cause leaking pinion input seals, and seriously strain the entire drivetrain. Since it's a somewhat lengthy explanation, I've tried to summarize (and help you to visualize) the need for adjusting your pinion angle with the following two crude sketches. The main goal is to adjust the length of the upper control arm so that the pinion is pointed directly at the output yoke of the transfer case. The bad pinion angle is sketched on the left; the corrected angle is sketched at right:
- Rubicon Express Super-Flex2 Adj. Rear Upper Control Arms
- Manufacturer's website: Rubicon Express
- SAFETY GLASSES!
- Socket set
- Socket wrenches
- Combination Wrenches
- Various length socket extensions
- Floor Jack (mandatory)
- Jack Stands (optional see updated notes at bottom)
- Wheel Chocks
- May also want: A helper/man-slave, air tools.
1. Raise and support the Jeep (leave the wheels on to check the pinion angle).
2. Remove the parking brake cable/bracket and ABS wiring bracket from the arm if equipped.
3. Remove the upper control arm nut and bolt from the axle bracket.
4. Remove the nut and bolt from the frame rail bracket and remove the upper control arm.
1. Position the upper control arm in the axle bracket (this is the Superflex2 end). See footnote #1.
2. Install the bolts on the axle brackets and finger tighten the nuts.
3. Raise the pinion into the proper angle with a floorjack. See here
4. Adjust the length and position the control arm (rubber bushing end) in the frame rail bracket.
5. Install the bolts on the frame rail brackets and finger tighten the nuts.
6. Remove the jack stands and lower the Jeep.
7. Check the pinion angle. See footnote #2.
8. Tighten the upper control arm frame rail bracket bolt to 55 ft. lbs. with your torque wrench.
9. Tighten the upper control arm axle bracket bolt to 55 ft. lbs. with your torque wrench.
10. Recheck the pinion angle. Repeat step 6 if needed.
11. Tighten the control arm jam nut tight to the frame end of the control arm. See footnote #3.
Footnote 1: Make sure to put the grease fitting towards the sky. Make sure to install the Super-Flex2 joint end in this axle bracket. The adjustable end connects to the frame rail bracket.
Footnote 2: If the pinion is pointing further down than it was with stock control arms, lengthen the control arms. If the pinion is too high, shorten the control arms. If the pinion is pointing directly at the rear tcase output yoke, then proceed to step 7.
Footnote 3: You may want to put locktite on this nut once you have the arms adjusted where you want them. See the final installation picture
Footnote 4: As a point of reference, my Jeep had about 4.5" of lift at the time of this writeup. This much lift required exactly 8 full turns of the adj. control arm from the shortest position. Later, with the RE suspension lift installed, I needed to extend the arm to 19 full turns. Each full turn extends the arm approx. 1/16"
Updated Installation Notes (shortcut)
After I installed my Rubicon Express 4.5" suspension system I needed to readjust these rear upper control arms again because due to the lift my rear pinion angle was off again. I found a shortcut for adjusting these arms that doesn't require jacking up the rear of the Jeep and removing the tires. You really only need to place the floorjack under the pinion while the Jeep is still on it's tires and jack the pinion to where it needs to be, adjust the arms, torque them down and let the jack down. Then check the pinion angle and move on. A 2-3 hour job just became a 1 hour job from my experience and you can do it without any help.
Page created on 9/15/2003
Last updated on 4/29/2004