john banks

Have a clonking noise from right front wheel which is intermittent, can be heard at fast cruise. Ever so slightly touching the brakes removes it completely. It can be louder or softer going around corners. No difference on acceleration, different gears, in neutral. Sounds like one clonk per wheel revolution. Started just after fitting new discs and EBC ceramic red pads. Stripping it down a few times afterwards has revealed no obvious contact between part that shouldn't be touching. The caliper (AP 4 pot) seems to be shimmed correctly, pistons seem to be working, pad wear so far looks even, discs are not hot after a run when the brakes have not been used heavily, certainly no difference between the side that clonks and the other side. The driveshaft has been re-greased after clicking recently, and there is a suspicion it may be that. Wheel bearing doesn't seem to have any abnormal play. I automatically blamed my brake installation, but I can't see anything wrong. The old pads are already in the bin sadly, and wasn't keen to deposit DS2500 rubbish onto the new discs given previous vibration trouble. The brakes and handling are fine. There is no vibration through the steering.

Suggestions?

RON

I realyy wish I knew John, you're so helpful everywhere else, it doesn't seem right that no-ones replied, even at this early stage.. there are a couple of possibilities, bearing in mind that it seems to be at each revolution of the wheel, is there a chance that theres a snag on the disc that's touching the pad each turn??
Are the pads loose in the caliper??
Is the caliper still bolted up tight??
Have you had the wheels balanced with weights placed in the wrong part of the wheel, maybe hitting the caliper??

I hope it sorts itself out soon....

Ron..
is it possible that the disc is just touching the caliper at one point each turn??

chrome

fwiw john- I have exactly the same thing..
sorry I cant be of any help tho

john banks

Thanks Ron and Chrome. The wheel wasn't rebalanced, but I'll check the proximity of the weights. However, this kit will go under wheels 1" smaller than I am running. Pads are not loose, need reasonable force to get it, feel about right, although we did grind the edges off to allow it to go in right, but I used to have to do this with DS2500 as well. Caliper is tight, and was loosened and refitted as well, no help.

Could be a snag on the disc, can't see it touching the caliper though with a wheel off and rotating it.

chrome

My new(ish) red dot carbon XF pads clonk when cold

thats on the brembo 4pot kit. (330mm discs)

stockcar

not sure from your post, but sometimes on the race cars.................

the steel pad guide (4 per caliper) in the base of the caliper can fracture/snap and allow more pad movement than normal............this allows the noise you mention???

alyn

dazc

I'll tell you what that is.
When you've put the brake pad anti-rattle clips back on you have put them the wrong way around. Ie, no preload on the pads to hold them in place. This causes the pad to lift and drop with each revolution of the wheel.
They should press firmly onto the pad holding it still, they do actually fit the wrong way (facing out) which causes this problem! Touching the brakes holds them in place so no rattle!
2 mins to sort so dont worry. Daz

dazc

Just had another thought too.
Mintex produce a sticky bitumen/material type shim. This sticks onto the back of your pad, and once the pistons press into it they imprint into the material. This stops the pads moving even more, as the pad can't slide up and down the pot.
It wears slightly over time but its good stuff. Anyway, best of luck, Daz.

john banks

There are no anti-rattle shims on these pads though.

Fixed it I think - well it has been OK for 40 miles. Andy F suggested that the disc may be out of true where the bell meets the hub by a different position to last time or a bit of rust. Thanks to T-uk's humour and late night lighting/garage we recleaned the mating surfaces and tried a different orienation, and for good measure reshimmed the bottom of the caliper mount a bit closer and it seems OK for now.

dazc

They dont come with the pads, they should be supplied with your ap kit from new. Thats the purpose of the central allen key bolt on the calliper to hold these in place.

[QUOTE=john banks]There are no anti-rattle shims on these pads though.

john banks

Got the AP kit used without them and it has never been a problem before with other pads, and does seem to be OK now as well. If it is a further problem I'll see if I can get some. Thanks for the advice, appreciated.

dazc

No problem, if it was used they may be missing. What happens is the back of the pad will tend to rust or get crap on it, and this will stop it sliding around without the clips. Put new pads in and theres nothing to stop it. Good luck anyway John. Daz

stockcar

very easy to sort new ones john..........................

alyn