Tech Tip: Worn Upper Arm Bearings May Cause Suspension Knock – UnderhoodService

Tech Tip: Worn Upper Arm Bearings May Cause Suspension Knock

When an Acura RL owner visits your shop complaining about a knocking noise from the front suspension when driving over bumps, the noise may be caused by worn upper arm bearings. The following tech tip may help you quickly diagnose and repair the problem ....

A knocking noise from the front of any vehicle can be a cause for concern. If the vehicle is an old pickup truck with 150,000 miles of hard off-road use, noises usually come with the territory and are sometimes acceptable. But, if the vehicle is a 1996-98 Acura RL, not only will the owner notice it, they will probably want it fixed right away.

When an Acura RL owner visits your shop complaining about a knocking noise from the front suspension when driving over bumps, the noise may be caused by worn upper arm bearings. The following tech tip may help you quickly diagnose and repair the problem.

DIAGNOSIS
1. Test-drive the vehicle over a bumpy road to verify the noise and to determine its location.
2. Raise the vehicle on a lift.
3. On the vehicle side where the noise is heard, hit the tire with a large soft-faced mallet while placing your hand over one of the upper arm bearings. Repeat this action with your hand placed over the other bearing.

• If you feel looseness or hear knocking from either bearing, go to the Repair Procedure.
• If no knocking noise is heard and no looseness is felt, look for other possible causes.
• If you heard the noise from both sides of the vehicle, repeat Step 3 on the other side.

REPAIR PROCEDURE
NOTE: This procedure does not require wheel alignment after completion.
1. Remove the wheel.
2. Remove the ABS wheel sensor wire harness from the upper arm.
3. Remove and discard the two upper arm 12 mm self-locking nuts.
NOTE: The upper arm bearings are built into the front anchor bolts.
4. Lower the upper arm, and pull it toward you to access the two front anchor bolts containing the upper arm bearings.
5. Remove and discard the front anchor bolt 10 mm self-locking nuts and the flange bolts, then remove and discard the front anchor bolts.
6. Install new front anchor bolts, making sure the large seal on the bolt faces outward. Secure the anchor bolts with new flange bolts and 10 mm self-locking nuts. Torque the nuts to 22 lb-ft (30 N-m).
7. Reinstall the upper arm, and secure it with new 12 mm self-locking nuts. Torque the nuts to 47 lb-ft (64 N-m).
8. Reinstall the ABS wheel sensor wire harness.
9. Reinstall the wheel. Torque the wheel nuts to 80 lb-ft (108 N-m).
10. Test-drive the vehicle to make sure the noise has been eliminated.

Accura and RL are registered trademark names and model designations of the American Honda Motor Company. All trademark names and model designations are being used solely for reference and application purposes.

Written by ALLDATA Senior Automotive Editor, Rich Diegle. Rich is an Advanced Engine Performance Certified, ASE Master Technician with an AA Degree in automotive technology and 23 years of dealership and independent shop experience.

For additional information, visit www.alldata.com.

 

You May Also Like

Jump Starting an EV

If an EV with a full battery won’t start, here’s how you can get it up and running.

Here’s a real-world scenario: A customer brings their EV into your shop for service, and it’s been there for quite a while because the parts are on backorder. After a few weeks, you get in the vehicle to move it out of your way, and the ignition won’t turn on. It’s acting like the battery is dead, so what do you do now?

Auxiliary Water Pump Diagnostics

A car or truck comes into your shop with a complaint of poor heater performance- the issue may be the auxiliary water pump.

Do You Know The Cause Of A No-Spark Condition?

A no-spark condition could be the result of communication errors or missing data from a dead module.

Belt-In-Oil Timing Systems

Oil contamination of the belt drive has been a death sentence, due to the rubber and fiber construction of the belt.

Building The Perfect Future By Mentoring

Share your stories of how you have helped others reach their goals.

Other Posts

Solving Intermittent Overheating

New cooling systems anticipate and influence changes in coolant temperature.

Spark Plug Fouling

Understanding why spark plugs get dirty.

PCV System DTC

PCV systems are far more complex now, but they are also much better at controlling crankcase pressure.

What Caused The Turbo To fail?

Up to 50% of turbocharger failures are due to oiling problems.