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Dial In Rear Pinion Angle Without the Extra Weight
Correcting rear pinion angle after a lift is one of the most important steps for driveline longevity, and the RK08311 makes it simple. This upper control arm pair uses lightweight 7075 aluminum construction with a fully adjustable design so you can tune your Jeep Wrangler JL or JLU's rear geometry precisely, without the extra mass of a steel arm.
Key Features
- RK08311 X Factor PRO aluminum rear upper control arms made from 1.375 inch 7075 aluminum
- Adjustable Adventure Series joint at the frame end offers 35 degrees of misalignment
- Krawler series joint at the axle end adds additional misalignment capability for a combined 95 degrees
- Fully adjustable in the vehicle for precise rear pinion angle tuning
- Machined wrench flats at the arm center simplify jam nut tightening
- Lightweight aluminum construction reduces unsprung weight versus steel arms
Fitment
| Year Range | Make | Model |
|---|---|---|
| 2018-2026 | Jeep | Wrangler JL/JLU |
Specifications
| Detail | Value |
|---|---|
| MPN | RK08311 |
| Location | Rear Upper |
| Material | 1.375 inch 7075 aluminum |
| Adjustability | Fully adjustable, both ends |
| Quantity | 2 (pair) |
| Warranty | Lifetime Warranty |
| Brand | Rock Krawler |
What's Included
- (1) Pair Rock Krawler RK08311 X Factor PRO aluminum rear upper control arms
- Mounting hardware
- Installation instructions
About Rock Krawler
Rock Krawler Suspension has spent decades engineering long arm and mid arm suspension systems, control arms, and shocks purpose built for Jeep Wrangler and Gladiator platforms. Based in New York, the company is known among off road enthusiasts for service free joints, abuse proof warranties, and components tested on real trails before they reach the shelf.
Related Parts on Our Site
- Rock Krawler 2018+ JL/JLU Front Upper Control Arms
- Rock Krawler 2018+ JL/JLU X Series Rear Lower Control Arms
- Rock Krawler 2018+ JL/JLU Front Upper Adventure Series Control Arms
FAQ
What is the RK08311?The RK08311 is a Rock Krawler X Factor PRO aluminum rear upper control arm pair for 2018 and newer Jeep Wrangler JL and JLU models, designed to let you adjust rear pinion angle after installing a lift.
Does it fit both the JL two door and JLU four door?Yes, this upper control arm fits both the two door JL and four door JLU since the rear suspension mounting points are shared.
Why do I need to adjust pinion angle after a lift?Lifting the suspension changes the angle between the driveshaft and pinion, and correcting it with an adjustable arm helps reduce vibration and extend U joint life.
Is the RK08311 heavier than a steel control arm?No, the 7075 aluminum construction is lighter than comparable steel upper control arms while maintaining strength for off road use.
Can I adjust this arm without removing it from the vehicle?Yes, the arm is designed to be fully adjustable in the vehicle so you can fine tune length without disassembly.
What is the total misalignment capability of this arm?The combined Adventure Series and Krawler series joints provide up to 95 degrees of total misalignment capability.
What warranty applies to the RK08311?Rock Krawler backs this control arm pair with a Lifetime Warranty against manufacturing defects.
Does installation require any special tools?Standard hand tools and a torque wrench are sufficient, along with the machined wrench flats for tightening the jam nuts.
Install Instructions
- Raise and safely support the rear of the Jeep on jack stands.
- Support the rear axle with a floor jack to control droop during removal.
- Remove the factory rear upper control arm bolts at the frame and axle mounting points.
- Remove the factory arms and set them aside.
- Thread the jam nuts onto the new arms and install them at the frame and axle brackets finger tight.
- Adjust arm length to achieve the correct rear pinion angle for your lift height.
- Torque all mounting hardware to the vehicle manufacturer's specifications.
- Tighten the jam nuts against the adjuster sleeve using the machined wrench flats.
- Cycle the suspension by hand to confirm clearance, then lower the Jeep and verify pinion angle.
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