G Man

Maybe someone has had this problem before and can help me. I am hearing a metal to metal tapping sound when I apply my brakes. It is coming from the front of the car and only makes the noise when I apply the brakes. Actually I have heard it occasionally when I let off the brakes, but mostly upon application of the brakes. It does not rattle or make numerous tapping sounds. When I apply the brakes it taps one time. If I let off and apply brake again I get one tap. I checked my calipers recently to make sure they were tight, and they were. Any suggestions as to where else to look?

FLanderhol

I had a simmalar problem on my 928 s4 but it was when i applied the gas between 1-2500 rpm and when i got back down using my brakes it turned out that one of the straps on my CATs were broken no biggie just cut them off!

heinrich

Could be a loose pad.

DG84S

There may be slack in a front wheel bearing or suspension component. Jack up each front wheel and lower until lower control arm rests on blocks with tire just clearing ground then check for play in wheel and links.

John Struthers

Jim,
I am suffering from the dreaded rotational squeak/squeal myself.
My attempts to cure the problem have not resolved the issue.
I tried a variety of fixes and others made suggestions (see page 6) to no avail though I haven't given Dennis Wilson's idea a shot yet.
If it doesn't work I'll try a set of pads other than the Pagid's along with a good clean-up and do another Mic'/runout check of the rotors.
Good luck.

jon928se

Most probably the stainless steel "sliders" (cant think of a good descrption that translates across the atlantic or pacific) - The stainless springy things that hold the brake pads in place. When the calipers start to corrode (Unfortunately Alu calipers are really good at corroding) the corrosion product, in this case that white powdery stuff that is really hard when you want to eliminate it, stops the stainless springs from being springs and stops the pads moving around smoothly in the caliper. Result the pads jump from there at rest position to the braking position with a clunk.

now is a really good time to RnR those calipers and treat them to a new coat of paint.

jon in nz

Kolbjorn S

The strangest of metal-to-metal noises under braking:
https://rennlist.com/forums/showthre...ight=transaxle
But please tell me it's something else!

hinchcliffe

More than likely the pads slide forward in the caliper when you apply the brakes. Try it in reverse gearthen forward. See what happens. Maybe the caliper is loose.