In this brief article, we are going to discuss the suspension issues that occur in Infiniti QX56 and what causes these failures.
The TopMost Common problems with Infiniti QX56 Suspension are:
- Clunking Noise in the Front
- Low Front Suspension Height
- Loose and Bouncy Rear Suspension
- Rear Lower Control Arm Rust
Infiniti QX56 Suspension
The first generation JA60 was based on the Nissan Armada full-size SUV F-Alpha Platform and therefore has mechanical similarities. The Infiniti QX80 is the facelifted and rebadged version of the QX56, both belonging to the same second-generation Z62 platform.
The Front suspension is a Double-Wishbone set-up with Coil Springs and twin-tube shock absorbers.
The Rear Suspension is also Double-wishbone with Coil Springs and an optional Pneumatic QX56 Self Leveling Tow Package Feature. In this package, a pneumatic actuator lifts the suspension whenever it senses extra load, so that the ride-height is constant irrespective of the load variation.
Poor Handling at the Rear
- Small undulations on the highway make the rear end sway and become unstable
Troubleshooting Poor Handling at the Rear
- First of all, since it concerns handling, the rear shock absorbers can be checked for any signs of leakage. Also the Bounce test can be done to see if the shock absorbers are still capable of damping
- Next would be the rear control arm bushings. Worn out Lower control arm bushings do cause handling problems.
- Next would be to check the wheel alignment at the rear. Verify, at the alignment shop, that the settings they use match the last revised settings recommended by the manufacturer (In case there was a Technical Service Bulletin communicating a revision in Alignment settings after the vehicle sold)
Clunking Noise in the front
- ‘Clunking’ and ‘Knocking’ Noises while driving
- Noise is very less on a smooth road and more apparent when driving over a rough patch
- This failure applies to all variants of the QX56
Troubleshooting Front Clunking Noise
- Front Knocking sounds that increase on a rough road are the signs that point to an issue with the Anti-roll bar(ARB) links
- The anti roll bar does not articulate so much on smoother surfaces and hence is less noisy
- The symptoms point to 2 probable Anti-Roll bar Issues:
- Anti-roll bar Drop Link failure
- Anti-roll bar Chassis Bush failure
- An easy way to diagnose ARB linkage noise is to hold each link and shake it by hand observing for movement or noise at each linkage point.
- The perfect way would be to remove the ARB Drop Links and check the ball-joint for excess play
Front Anti-roll bar-to-Subframe mounting bush failure
- The Anti-Roll bar (ARB) bushings are the isolators between the ARB and the vehicle’s chassis. The bushings also ‘secure’ the ARB in place and restrict excessive movement so that the ARB can properly function
- The ARB is under torsional loads while the car is undergoing “Roll” motion either during cornering or Rough Roads.
- In these situations, when the ARB undergoes torsion, the mounting bushes also share part of the road loads.
- Bushings that have aged, hardened, or simply worn out and become loose tend to cause noise as they allow unnecessary movement of the ARB.
- While refitting the Antiroll bar subframe bushing use a good anti-seize paste at the contact surface between the anti roll bar and the rubber bushing
- Anti-Seize application could be repeated periodically in order to prevent excessive wear, say, every 50K miles or so.
- For improving handling, you could search in the aftermarket for the same bushing with harder material. The harness is generally denoted by the Shore ‘A’ hardness number.
- Beware that a harder sway bar bushing would lead to a slightly harsher ride quality since the harder bushings do not allow vertical movement of the anti-roll bar, thus increasing roll-resistance and harshness on rough roads
Front Anti-roll bar End link Failure
- The ARB-to-suspension connection is done using ARB end links.
- On the front axle, the end links use a sealed ball joint design that has a significant range of motion sufficient for the various movements of the front suspension.
- The rubber boot that protects the end link Ball-joints can tear, allowing the joint lubrication to seep out and exposing the ball joint to corrosion. The result is a clunking noise from the worn joint.
- If the end links’ mounting fasteners have loosened on either end, it could result in clunking noise.
- When changing the Anti Roll Bar End Links (also called Drop Links), Jack up both sides of the car.
- If you jack only one side at a time, there will be a twist in the anti-roll bar because of which you would find it difficult to align the anti-roll bar and end link at the bolt hole.
Low Front Suspension Height
Symptoms of Low Front Suspension:
- This applies only to QX56 trucks with the Air Suspension option
- The front suspension sits at a low ride height
- Hissing noise coming from the front once the truck is started
- While driving, the rear axle feels floaty as if there is no suspension. The bump stops hit often.
Troubleshooting Low Front Suspension
- If your truck has already crossed 75K miles, then you might have reached the end-of-life of the Air Springs.
- The Hissing noise is indicative of the presence of leaks in the system leading to loss of air pressure in the Air Spring.
- The floaty feeling is also clearly due to the low air pressure in the Air Springs
- If the Air springs have a lot of mileage on them, then the source of the leak could be the cracked Rubber of the Air Springs themselves.
- This can be either visually inspected or done using a “Soapy Water Solution” bubble test.
Slow Raising of Ride Height
- Compressor runs everytime the vehicle is started
- When rasing the suspension, the operation happens very slow
- Normal Ride height seems lower than factory spec
Troubleshooting Slow Raising of Ride Height
- The slow response and overworking of the compressor all point to a possible air leak somewhere in the air suspension system
- The most probable potential leakage positions would be:
- The Air Springs
- The Valve Block
- Every Air Connector Fitting on the Air springs, Valve Block and Compressor
- Leakage can be detected using a soapy water (50:50 ratio) bubble test. After spraying the solution at all potential positions, observe for persistent bubbles that reappear even after wiping
Loose and Bouncy Rear Suspension
- This issue applies to QX56 trucks with or without the Air Suspension Option
- The Rear suspension feels extremely bouncy
- Handling feels vague with a lot of roll
Troubleshooting Loose and Bouncy Rear Suspension
- Bounciness is related to weak damping. The shock absorbers are basically unable to dampen bounce.
- With weak rear damping, cornering ability of the vehicle is highly compromised and leads to excessive roll
- To confirm this, you can do a bounce test.
- At the rear of the vehicle, at any one corner, apply your weight vertically downwards in such a way that the suspension starts to bounce at that particular corner.
- Push downwards continuously in an oscillating motion till you now have caused maximum vertical movement of the corner.
- Now leave the corner and watch how many times it bounces on its own.
- If it takes more than one oscillation to settle, then it is confirmed that the shock absorbers have gone weak.
Rear Lower Control Arm Rust
- Seen on 2014 model QX56’s
- Mostly seen on vehicles that live in the Snow-Belt where there constant ice and salt on the roads
- It is likely that the surrounding suspension components are also affected by corrosion. Be sure to check the upper control arm, Shock Absorber and Springs. Even if they are only beginning to corrode, they would fail imminently.
In this brief article, we have discussed the suspension issues that occur in the Infiniti QX56 and what causes these failures.