Knocking noise under braking

J

Jez_m

Member
Hi all, last Wednesday i changed all the brakes on the car, new discs, pads and fluid change all round. Since then i have an odd 'knocking' noise under medium to heavy braking that is coming from the rear drivers side. Almost sounds like something 'catching' on a rotating part as the brakes are applied.

It isn't affecting braking at all and doesn't occur under light braking either. At the weekend i took that particular brake apart and put it all back together, nothing out of place, everything is tight and in the right place, pads moving freely and wearing evenly. Struggling to work out what it could be! Any ideas? There was no noise prior to fitting the new brakes. I have fitted some 20mm spacers on the back, which went on at the same time, with longer bolts however they are a good fit, tight and no noises from the other side. Can't think that they could have any affect or cause any noise under braking anyway though.

Cheers
Jez
 
Does the break peddle shudder also while breaking?

New rotors and all, it could be that the run out on the rotor on the side you question is way out of tolerance. If I recall correctly less than 10MM was acceptable.
I used to make rotors on cnc's and know if the run out is bad, you will experience bad shudder, wobble on a tire, rotor, and in the foot peddle for the brakes.

Suggest swapping from one side to the other and see if it follows. Imagine it will if the run out on the rotor is loopy. Or you allowed a piece of extra unidentified foreign matter lodge in while installing. Seen that happen too.

One of the spacers could also be out of tolerance. Likely the side you suspect.

If it was my car I would remove the spacers and see how it acts, marking the suspect side. Then reinstall, if there was no problems only on the other side and see if it re animates.
 
Kap'nZ4 said:
Does the break peddle shudder also while breaking?

New rotors and all, it could be that the run out on the rotor on the side you question is way out of tolerance. If I recall correctly less than 10MM was acceptable.
I used to make rotors on cnc's and know if the run out is bad, you will experience bad shudder, wobble on a tire, rotor, and in the foot peddle for the brakes.

Suggest swapping from one side to the other and see if it follows. Imagine it will if the run out on the rotor is loopy. Or you allowed a piece of extra unidentified foreign matter lodge in while installing. Seen that happen too.

One of the spacers could also be out of tolerance. Likely the side you suspect.

If it was my car I would remove the spacers and see how it acts, marking the suspect side. Then reinstall, if there was no problems only on the other side and see if it re animates.
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No shudder through the brake pedal which makes me doubt it is the rotors. However, your suggestion of swapping sides is worth a try i think. Will first try removing the spacers and see if that has any effect.
 
if its not your brakes check the strut bars in the engine bay are tighten to the correct torque.
 
mac27040 said:
if its not your brakes check the strut bars in the engine bay are tighten to the correct torque.
Click to expand...

Noise is 100% coming from the rear brake / wheel area but i'll check those anyway. :thumbsup:
 
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