The AWD Nissan Altima Drivetrain: FWD vs. AWD Architecture
Before diving into universal joint (U-joint) diagnostics, it is critical to establish a fundamental mechanical truth about the Nissan Altima platform. The vast majority of Nissan Altimas on the road are Front-Wheel Drive (FWD) vehicles equipped with the QR25DE 4-cylinder or VQ35DE V6 engines. These FWD models utilize Constant Velocity (CV) axles and half-shafts to route power to the front wheels; they do not possess traditional longitudinal driveshafts or U-joints.
However, the AWD Nissan Altima drivetrain—specifically found in the 2007–2012 V6 AWD models (such as the 3.5 SR AWD)—features a completely different rear architecture. These models utilize a Power Take-Off (PTO) unit attached to the transaxle, which routes torque via a two-piece or one-piece propeller shaft to an electronically controlled rear coupling and rear differential. It is at the rear differential pinion flange where the traditional U-joint resides. If you are experiencing driveline clunks or high-speed vibrations in an AWD Altima, the rear propeller shaft U-joint is a primary suspect.
Anatomy of U-Joint Failure in the Altima AWD
The rear differential U-joint on the AWD Altima is subjected to immense rotational stress, road debris, and moisture. Unlike CV joints which are enclosed in a protective rubber boot, U-joints rely on internal needle bearings packed with grease and sealed by fragile elastomeric lip seals.
The Mechanics of Degradation
- Spalling and Brinelling: Over time, the microscopic needle bearings inside the U-joint caps wear down. When the grease degrades or becomes contaminated with silica (road dust), the bearings begin to spall (flake) or brinell (dent the cross trunnion), causing rotational binding.
- Seal Extrusion: Winter road salt and extreme heat cycles cause the rubber seals to crack. Once water infiltrates the bearing cap, it emulsifies the lithium-complex grease, leading to rapid oxidation and catastrophic needle bearing failure.
- Yoke Ear Deformation: In high-mileage AWD Altimas (120,000+ miles), the repeated torque load from the 3.5L VQ35DE engine can slightly ovalize the yoke ears on the driveshaft, allowing the U-joint caps to walk or spin, which destroys the mating surfaces.
Identifying Failing U-Joints: The Diagnostic Matrix
Diagnosing the AWD Nissan Altima drivetrain requires isolating the noise from the transaxle, the PTO, and the rear differential. Use the following matrix to correlate your symptoms to specific U-joint failure modes.
| Symptom | Driving Condition | Probable Failure Mode | Verification Test |
|---|---|---|---|
| Metallic Squeak / Chirp | Low speed (5-15 mph), off-throttle | Dry needle bearings; grease depletion | Crawl under vehicle, rotate shaft by hand. Listen for dry scraping at the rear diff flange. |
| Heavy Clunk / Bang | Shifting from Reverse to Drive | Excessive cross-to-cap clearance; worn trunnions | With wheels chocked and parking brake on, twist the driveshaft firmly. More than 2mm of radial play indicates failure. |
| High-Speed Vibration | 55–70 mph, under light load | U-joint binding causing secondary couple vibration | Use a dial indicator on the driveshaft tube near the U-joint. Runout exceeding 0.020 inches requires replacement. |
| Humming / Growling | Coasting down from highway speeds | Differential pinion bearing (Not U-joint) | Isolate by loading the drivetrain. If noise changes with load vs. coast, suspect the rear diff, not the U-joint. |
OEM vs. Aftermarket: Part Numbers and Sizing
When servicing the rear propeller shaft, you have the option of replacing the entire driveshaft assembly or pressing in a new U-joint. While Nissan often pushes the complete shaft assembly, the U-joint itself is a serviceable wear item. According to RockAuto and aftermarket driveline catalogs, the rear U-joint typically aligns with a standard Spicer 1310 series metric or imperial equivalent, depending on the exact production month.
| Component | OEM / Reference Spec | Aftermarket Equivalent | Est. Cost (2026) |
|---|---|---|---|
| Rear Diff U-Joint | Nissan 39740-JK00A | Neapco 1-0154 / Spicer 1310 | $35 – $55 |
| Flange Bolts & Nuts (4x) | Nissan 39744-JK00A | Grade 10.9 Metric Flange | $8 – $15 |
| Complete Prop Shaft (AWD) | Nissan 39600-JK00A | Dorman 936-Series / OEM Surplus | $650 – $950 |
Note: Always verify your specific VIN. Nissan utilized slightly different propeller shaft configurations for the 2007-2009 models compared to the facelifted 2010-2012 AWD models.
Step-by-Step U-Joint Replacement Procedure
Replacing the U-joint on the AWD Altima requires a hydraulic press or a heavy-duty C-frame U-joint press tool. Attempting to hammer out the caps will almost certainly deform the yoke ears, turning a $45 repair into a $900 driveshaft replacement.
Step 1: Index Marking and Removal
Driveline balance is highly sensitive. Before unbolting anything, use a yellow paint pen or center punch to make alignment marks across the U-joint yoke and the rear differential pinion flange. Reassembling the shaft even one spline or bolt-hole out of phase will introduce a severe harmonic vibration at highway speeds.
Using a 12mm or 14mm socket (depending on the exact hardware revision), remove the four flange nuts securing the U-joint to the rear differential. Support the driveshaft with a bungee cord or wire to prevent it from hanging on the center support bearing or the front PTO joint.
Step 2: Extraction and Cleaning
Remove the external snap rings (if equipped) or pry off the injected plastic retaining rings common on OEM Nissan shafts. Place the yoke into a hydraulic press. Press the cross through the yoke ears, capturing the old bearing caps in a receiving socket.
Once the cross is removed, thoroughly clean the inside of the yoke ears with brake cleaner and a brass wire brush. Inspect the bearing cap bores for scoring. If the bores are gouged or out-of-round (measure with a micrometer; variance should not exceed 0.001 inches), the yoke is compromised, and the entire driveshaft must be replaced.
Step 3: Pressing the New Assembly
According to Spicer Parts engineering guidelines, you must never press on the new U-joint caps using the cross itself, as this will brinell the new needle bearings before the vehicle even leaves the lift. Instead, press the caps into the yoke ears using the old bearing caps or a specialized stepped press die.
Install the new cross, ensuring the grease zerks (if equipped) are oriented toward the driveshaft tube for accessibility. Press the caps in until they are fully seated, then install the new snap rings. If the U-joint feels tight or 'binds' when articulated, strike the yoke ears gently with a brass drift and a dead-blow hammer to relieve cap tension and center the cross.
Step 4: Reassembly and Torque Specifications
Align your index marks and mate the U-joint to the rear differential flange. Nissan specifies new flange hardware for reassembly to prevent fatigue failure. Apply a drop of medium-strength threadlocker (Loctite 243) to the new flange bolts.
- Flange Bolt Torque: 36 ft-lbs (49 Nm)
- Center Support Bearing Bolts (if removed): 25 ft-lbs (34 Nm)
- PTO Flange Torque (Front of shaft): 43 ft-lbs (58 Nm)
When to Replace the Entire Driveshaft Assembly
While replacing just the U-joint is cost-effective, there are scenarios where the entire AWD Nissan Altima drivetrain propeller shaft must be replaced. If the vehicle has been driven extensively with a failing U-joint, the resulting vibration often destroys the center support bearing and damages the rubber harmonic damper surrounding the shaft. Furthermore, if the front CV joint (which connects the shaft to the PTO) exhibits boot tearing or clicking, sourcing a complete remanufactured or OEM surplus shaft from a trusted supplier is vastly more reliable than attempting to rebuild a high-speed, dynamically balanced two-piece assembly in a standard garage environment.
For official service bulletins and factory torque verification, certified technicians should always cross-reference the latest documentation available via Nissan Technician Info. Proper maintenance of the AWD driveline ensures the longevity of the rear coupling and differential, keeping the Altima's all-weather capability intact for years to come.
