Brake squeal

[TomB]

Morning,

I've changed my front callipers over winter from the 2 pot Triumph calliper  to the HiSpec UL4 calliper, both with Mintex 1144 pads.

The new pads are now bedded in, but I've noticed a squeal when coming to a halt eg at a junction. I put some copper grease on the rear of the pads before fitting them which I thought was mean to stop this.

What it is that makes the brakes squeal at low speed when coming to a halt, but not when the brakes are used in normal driving use? Is there anything else I can do about it aside from copper grease?

Apart from the squeal, the HiSpec callipers seem good. The balance seems to be maintained front to rear and they work at least as well as the old Triumph callipers, maybe a little more retardation but not loads more.  Its probably be a placebo effect, but loosing 2.4kg each side with the new callipers and CF wings seems to make the car feel lighter on its feet.  

[Paul Mason]

Mine squeal exactly the same (Caterham 4 pots and vented discs). Done copperslip on pads and cleaned everything to no avail. Have just learned to live with it (if nothing else makes it sound like a racing car...... tho admittedly I am quite immature)

[TomB]

Thanks Paul.  Its just annoying, and if I can do something about it with a rear pad treatment/glue/pad Id probably give it a try.   Ive read something about filing the leading edge of the pads 45 degrees I think, but not sure quite what this is about/ for. 

[elie boone]

The squeal is cause by vibration, filing an angle on the side of the friction material reduces this vibration.

[TomB]

Thanks Elie - can you explain further.  Is this across the full thickness of the pad, or just a chamfer on the part that touches the disc?  Where on the pad does it go - the front edge of the pads, facing forward, or the bottom edge of the pads where the disc meet the pad as it rotates?

[DJ.]

When I fitted 1144 pads in my standard callipers, I just applied copperslip as usual and had terrible squeal. I removed the pads, cleaned them an fitted the strange stick on pads that came in Mintex box, and they never squealed again.

[SM25T]

Try a small 45 degree chamfer along the leading edge of the pads with a file It's the first bit of pad that the disc sees.

[TomB]

Ive not got any sticky backing pads with my brake pads. I’m sure I’d be able to pick some up from eBay. Regarding the chamfer, do you mean by leading edge, the narrow edge of the pad, at the bottom, when placed in the calliper at the rear of the disc? When the wheel rotates forward, this is where the disc frost meets the pad. 

[SM25T]

Yes

[Toby S]

Similar experience to DJ with standard callipers and Mintex 1144's - fitted triumph metal shims, plus a smear of copper grease which solved the problems - the mintex stick on pads are effectively stick on shims although I've found the pads can be a pain to get out after use as the piston embeds in the pad and almost gets welded in the stick on pad due to heat generation thus making it difficult to pull the pads out without getting the calliper well open first and liberal use of a Longbridge screwdriver. 

[thompster]

I've recently swapped from unknown Mintex in standard calipers for Ferodo DS2500 in Wilwood Powerlites.  The mintex squealed when cold/slow no matter what I did - chamfered edges, 3M anti-squeal backing, coppaslip.  The ferodos are (so far) as quiet as a mouse.

[Bricol]

Most pads should have the anti-squeal shim already fitted - used to do numerous jigs for them to properly align and position them for attaching in a previous life.