Clunking while braking

[cchase]

I just replaced the pads and rotors on our 2002 Malibu today.

Used GM pads and rotors, everything new.

On the passenger side, there is a clunking that matches wheel rotation speed under braking. Under light braking, there is no noise apparent. The harder you push the pedal, the louder the clunking noise gets, and you can just barely feel it in the chassis of the car. From outside the car, the noise is apparent but quiet - I suspect an amount of noise in the car is due to reverberations through the chassis of the car - but it's quite evident inside the car.

I've taken everything apart and re-assembled 3 times so far and haven't seen anything out of place... no strange markings, rubbings, there are no burrs on the rotor or anything out of place looking. The wheel spins freely with no noise.

Where should I look next?

 

[cchase]

To add, I replaced the pad mounting brackets (the thin sheet-metal pieces), the spring that holds the pads in place that is attached to the caliper (only after several tries with the old one, which seemed fine). The slide pins are free and lubricated and the caliper slides freely.

 

[JC1]

Originally Posted By: cchase
I just replaced the pads and rotors on our 2002 Malibu today.

Used GM pads and rotors, everything new.

On the passenger side, there is a clunking that matches wheel rotation speed under braking. Where should I look next?


Check to see if you torqued your lug nuts properly. I didn't torque my wheels with a torque wrench one time and under breaking a low speed I could hear a clunking noise.

 

[cchase]

I went through torquing the lug nuts each and every time with no difference. I even swapped lug nuts from the other side to see if somehow they were applying force to the rotor/wheel differently.

I did just find an interesting Youtube video with a similar noise (albeit louder). One of the comments mentioned that the spiral cut in the rotor face can allow the pad to ride up the "threads", top out and then slap back down. This seems feasible to me since light braking would potentially not allow the pad to "grip" the spirals on the rotor face...

 

[cchase]

http://www.youtube.com/watch?v=Oc3BmtLJ2cY

That is the video I found. My noise is not nearly that loud but I would consider it to be the "same" noise.

I also forgot to mention initially - the noise does not change if you turn while braking.

 

[justinf89]

Ive got the exact same problem with new everything on my explorer. Never heard it before and cant figure it out.

 

[iluvhonda]

On Hondas we had a similar problem while braking. Check your sway bar bushings and or your equivalent radius rods setup bushings.

 

[mopar_monkey]

did you lube the slide pins and points were the pad contacts the caliper and bracket? if a rotor hasn't had a finish cut you can have a similar sound, even new rotors should have a finish cut before install.

 

[cchase]

I don't think it is suspension related. This happened as a result of the brake job. Nothing else was touched.

Slide pins and all pad mounting points were lubricated before install.

 

[doitmyself]

You could switch the rotors from side to side and see what happens.

Did you wash the rotors in detergent water before install to remove any surface treatments?

Some people sand their rotors with 120 to 150 grit paper to ensure a nondirectional finish, remove any glaze, etc.. Google for more info.

I had thumping with my last Caravan rear brake job (drums). It turned out that the Carquest Chinese drums were defective out of the box.

Good luck.

 

[cchase]

I did clean everything with brake parts cleaner.

I thought about swapping rotors from side to side. But after thinking about it, the problem would still exist on the right side if it is due to the cutting on the rotor surface - since the spiral direction would reverse.

I guess my easiest option is to scuff up the surface with some sandpaper and see what happens.

I've never had an issue with "out of the box" rotors but there's a first time for everything.

 

[Warstud]

Thinking the pad isn't wide enough and is sliding back and forth in the direction of wheel rotation causing a clunk. Have someone move the car and apply the brakes while you observe the pads for movement.

 

[VicVinegar]

Interesting, I just had rotors and pads done and heard an intermittent clunking a few times after driving off. It wasn't related to braking though, and hasn't returned. I brought it back to the shop, they put it on the lift and everything looked like it was in its place.

I do notice a slight vibration like there is some grinding going on from the front on the side the clunking came from. I'm not sure if it is just some break in, or if something needs to be adjusted.

 

[cchase]

Sanding the rotor did the trick.

 

[doitmyself]

Originally Posted By: cchase
Sanding the rotor did the trick.


I hope that cures the problem. I guess some rotor finishes are not quite right and sanding "breaks up" the pattern.

Also, I was taught that detergent and water actually cleans metal better than solvents because it works any embedded particles out of the nooks and crannies. I believe this is prescribed for engine blocks too.

 

[mechtech2]

Having everything new and lubed actually worked to make the 'clunk' louder. The parts were freer to move.
Just drive it and hope it doesn't come back - the odds are good for you.

 

[mechanicx]

Originally Posted By: cchase
Sanding the rotor did the trick.


Sounds like it might have been excessive runout in the hub bearing stacked with whatever rotor runout. It should wear true.

I doubt this is an issue but on this model supposedly the inboard and outboard pads can be erroneously interchanged during installion. I say supposedly because the inboard pad has an obviously taller tab that fits against the clip in the caliper. But here is a TSB about that. The inboard pad (piston side) has the wear sensor and the sensor should be positioned on the leading edge (facing upward) of the rotor.

 

[cchase]

Originally Posted By: mechtech2
Having everything new and lubed actually worked to make the 'clunk' louder. The parts were freer to move.
Just drive it and hope it doesn't come back - the odds are good for you.


Originally Posted By: mechanicx
Originally Posted By: cchase
Sanding the rotor did the trick.


Sounds like it might have been excessive runout in the hub bearing stacked with whatever rotor runout. It should wear true.

I doubt this is an issue but on this model supposedly the inboard and outboard pads can be erroneously interchanged during installion. I say supposedly because the inboard pad has an obviously taller tab that fits against the clip in the caliper. But here is a TSB about that. The inboard pad (piston side) has the wear sensor and the sensor should be positioned on the leading edge (facing upward) of the rotor.


Thanks for the information. To clarify - there was no clunk (loud or otherwise) previously.

Interesting note on the pads. I simply matched the old pads which it seems agrees with what you are saying, mechanicx. I'm not sure how they could get confused inboard to outboard though, with such different tabs.