NB8A - rubbing/scratching noise under braking.

[Kenstaki]

Hi Guys, I wonder if you guys have experienced something similar.

I am hearing a rubbing sound similar to what it would sound like if someone were to hold some cardboard against a spinning axle.

Some symptoms and info.

It doesn't occur when rolling.
It doesn't occur when accelerating.
I can only hear it under braking just when I'm about to come to a stop (<10 km/h).
It sounds cyclic, so I hear it for about 120 degrees of rotation.
I can hear it when braking in a straight line.
I've recently changed my wheels from 15x6 to 15x7 with the same tyre.
I do not see any debris on my brake discs.
I've checked the tightness of my wheel nuts.

I can't tell if it's coming from front or rear. Any areas I should check on?

EDIT: Really should have searched the forum first. Saw some mention about loose brake pads and damaged wheel bearings.

[93_Clubman]

Check brake pad thickness as it sounds like one corner or more might have just reached the wear indicator.

[Hjt]

Are your inner.guards scrubbing?

[project.r.racing]

It sounds cyclic, so I hear it for about 120 degrees of rotation.

As in the other 240 degrees it doesn't do it, then it comes back for 120 degrees?

if so, warped old rotor.

[Kenstaki]

yeah that sounds logical

[project.r.racing]

how old are the rotors?

[Kenstaki]

4 yrs.

[jorgan92]

Hate to try and point out the obvious but how new are your wheels? Just saw them in the show off your rim thread, it could be guard liners scrubbing or guards themselves....

[Kenstaki]

Hate to try and point out the obvious but how new are your wheels? Just saw them in the show off your rim thread, it could be guard liners scrubbing or guards themselves....

Are you referring to the actual wheel guard that's part of the body of the car? Because I only hear the noise under braking, I tend to think it's related to the brake rotor. However, I've only noticed the sound after I've switched the wheels, so I'll would say it's probably related to the new wheels.

[jorgan92]

Hate to try and point out the obvious but how new are your wheels? Just saw them in the show off your rim thread, it could be guard liners scrubbing or guards themselves....

Are you referring to the actual wheel guard that's part of the body of the car? Because I only hear the noise under braking, I tend to think it's related to the brake rotor. However, I've only noticed the sound after I've switched the wheels, so I'll would say it's probably related to the new wheels.

Under braking the car would dip forward a bit at the front. usual suspects are the plastic guard liner, or the guard its self. Jack up the car, take of the front wheels and have a look. look for worn areas on the black plastic. marks on the tire scuffing on bolts, whatever.

Out of curiosity do you know what size and offset the wheels are?

[Kenstaki]

15x7 +45 205/50

[Hjt]

I mentioned this up top, under braking your vehicle lurches forward and will scrub on the inner most part of the car. It did for me.

[Kenstaki]

Good call Hjt and jorgan92. I jacked up the front right corner and had a look under the guard.

From the photo, you can see a raised section of guard with dark black tyre scrub marks.



I've firmed up the adjustable front suspension in the hopes it'll prevent scrubbing under forward weight transfer.

Case Closed!

[NitroDann]

That wont do anything, you need stiffer springs or raise the ride height.

Dann

[Kenstaki]

Thanks Dann, I read into it further and have gathered that adjusting the damping rate on the shock will not alter the amount of deflection on the suspension, but instead increase the time to deflection.

I expect increasing damping rate would reduce tyre scrubbing to occur on sudden bumps but not under gradual braking.