On my Opel/Holden Astra H (150KKm, front wheel drive, m32 6-speed manual transmission) I hear a slight grinding noise from the right-front, starting at about 40 km/h. The noise is synchronous to the vehicle speed, independent of engine rpm. It remains the same if I press the clutch, change the gear or switch to neutral. It also does not change if I make turns. The best description of the noise would be the sound of a steel brush pressed against a turning shaft. What i am not sure: There is a possibility that the sound would be more silent while accelerating.
So the possibilities would be: The differential in the gearbox, the intermediate shaft bearing, the CV joints of the axle, the wheel bearing or a slightly seized brake.
I tend to exclude the wheel bearing: Because the noise remains the same when making turns and the wheel bearing has no feel-able play when I jacked up the car and shacked the wheel.
When turning the wheel by hand I cannot identify any irregular sound.
I would appreciate any ideas on how to analyze the problem.
Just the following updates:
- The pads and rotors are new.
- There is nothing that rubs on the wheel.
- The boots are intact and not leaking.
- The transmission fluid is new. The transmission has a bad reputation for failing early (wrong bearing preload in the factory).
- The sound does not go away when tipping the brake
- The sound is very faint on the first km's and gets louder after about 10 km.
- I observed that the brake makes a slight periodic grinding sound when turning the wheel, always on the same position (perhaps a slight side run-out) but i doubt that this would be the issue. I will compare it against the other rotor.
- In the next day I will remove the axle from the wheel bearing and check the wheel bearing, the intermediate shaft bearing and the cv joint
- When changing the brake pads I lubricated the guide bolts. The next day I found out that the bolts should be mounted dry (ATE brake system). Perhaps the rubber bushings surrounding the bolts swell in combination with the grease. I will change the bushings this week