AXLE SHAFT/ U-JOINT GUIDEUpdated 2 months ago
AXLE SHAFT/ U-JOINT GUIDE |
U-Joint Sizes for Axle Shafts
U-joints (universal joints) connect the inner and outer axle shafts and allow for angular movement as the wheels steer or the suspension cycles.
Common U-Joint Sizes:
U-Joint | Cap Size | Overall Width | Strength (Approx.) |
Dana 30 (1310 series) | ~1.06" | ~2.94" | ~4,000 lbs |
Dana 44 (Spicer 297/760X) | ~1.19" | ~2.94" | ~5,000-6,000 lbs |
Dana 60 (Spicer 1480 or 1550) | ~1.375" | ~3.22-3.75" | 7,000–9,000+ lbs |
Key Points:
- Larger U-joints = higher strength, but also more stress on surrounding components.
- Aftermarket U-joints (like Spicer or CTM chromoly) offer more durability than OEM.
- Weak point is usually the ears of the axle shaft, which can stretch and fail before the U-joint breaks.
RCV Shafts (Constant Velocity Joints)
RCV Performance shafts use constant velocity joints (CVs) instead of traditional U-joints. These are more like what's found in IFS vehicles or front-wheel drive cars.
Benefits:
- No binding at full steering lock – U-joints lose smooth motion at higher angles; RCVs do not.
- Stronger under articulation – Constant torque transfer across the steering arc.
- Sealed CVs – Better at keeping dirt and water out, increasing longevity.
- Smoother operation – Less vibration and stress on steering components.
Drawbacks:
- Cost – RCVs are significantly more expensive than traditional U-joint shafts.
- Maintenance – While sealed, CV joints do benefit from occasional inspection or regreasing (on serviceable models).
RCV vs U-Joint Axle Shafts: Comparison
Feature | Traditional U-Joint Shafts | RCV CV Axle Shafts |
Turning Strength | Weaker at full turn | Strong throughout turn |
Binding at Angle | Yes (especially over 25°) | No |
Smoothness | Rougher at extreme angles | Very smooth |
Durability in Mud/Water | Moderate (open joints) | High (sealed) |
Maintenance | Low to moderate | Low to moderate |
Cost | Lower | Higher |
Ideal Use | Mild to heavy off-roading, cost-conscious builds | Hardcore off-roading, rock crawling, extreme angles |
Summary:
- U-joints: More affordable and traditional, but can bind at high steering angles and wear out faster under stress.
- RCV CV shafts: Superior performance in high-angle, high-torque situations. Perfect for rock crawlers or anyone who pushes their rig hard.
If you're building a hardcore trail rig or rock crawler, RCVs are often worth the investment. But for weekend wheeling, overlanding, or moderate trails, high-quality U-joint axles with chromoly shafts are usually sufficient.