Noisey Brakes

tetlow · Post by **tetlow** » Tue Jun 12, 2007 8:03 pm

I have grooved / dimpled solid brake discs with Green stuff pads.
They work fine but are noisey when working. It is a sort of hiss sound when under load.
The braking is smooth and predictable.
Is this noise normal.

Cheers

Dave

Post by **katanaman** » Tue Jun 12, 2007 8:14 pm

cant comment on your setup but its very normal on my Focus.

kiwicar · Post by **kiwicar** » Wed Jun 13, 2007 9:12 am

Hi Dave
Have you checked for a small stone jammed between the pad, hub and caliper? normally lowest point on the caliper ? this can be the problem(was many times on my Midget)
the other one is do you have any form of anti squeel pad behind the break pad? can be made out og old oil tin if needs be.
Mike

tetlow · Post by **tetlow** » Wed Jun 13, 2007 12:15 pm

Hi Mike.
Thanks for the help.
This noise has been from new and has not changed in 2000 miles.
It is a sort of hissing sound and continues for a few seconds after the brake pedal is lifted until the pads retract back. There is then no noise at all. (Except the sound of a MG slowly breaking up !!)
I read recently that drilled and slotted discs are noisey.

Is this true? Do you think that they should be quiet?
I have the Green Stuff pads that look to have a sort of shim fitted to the inside of the pad. I assumed this was anti squeal but I could be wrong.

Dave

kiwicar · Post by **kiwicar** » Wed Jun 13, 2007 4:21 pm

My Bike brakes are like you described when applied and are drilled and slotted but I had always put it down to them being fully floating discs.
Mike

Post by **katanaman** » Wed Jun 13, 2007 4:45 pm

grooved disks will always be noisier

JP. · Post by **JP.** » Wed Jun 13, 2007 5:56 pm

Grooved/slotted solid discs can be noisy in my experiance.
The grooved/slotted vented discs are not noisy.

It has nothing to do with the grooves but with the slots on solid discs.
On vented discs the air can escape while the slots passes the brake pads while on solids the air heats up between the slots and pads and while the slots passes the heated up air makes the noise.

Trieing to translate this from Dutch to Englisch to I'll hope this makes sense what I wrote.

tetlow · Post by **tetlow** » Wed Jun 13, 2007 6:33 pm

Sounds good to me.
I was told that through drilled discs are weaker than the dimpled ones so I chose the latter.
If I had known I would have taken the risk.
I wonder, if I cut slots in the pads???

Dave

Sondar · Post by **Sondar** » Fri Jun 15, 2007 2:35 am

What would worry me is that you mention that the sound is maintained for a few seconds after the pedal is released. That should mean that it's nothing to do with the pads or disks because the pads should release as soon as pressure is removed from the pedal.

Could you have a problem with the brake servo?

tetlow · Post by **tetlow** » Fri Jun 15, 2007 7:42 am

I am using Silicone fluid and there is still some air in the system. The brakes work fine but the second pump on the pedal is always harder than the first.
I assumed that the delay was caused by the lower pressure transfer rates etc caused by the air not allowing the piston to immediately retract.

I will be soon stripping the front suspension to replace all the bushes so I will go over the brakes.
The Servo, Master Cylinder and Braided hoses, calliper pistons and seals are all relatively new. (2000 miles)
Dave