Hi, my name is David Vilchez, this is my first post, I work in the Auto Industry.
So, a Braking pad from TRW landed in my hands and it has a diagonal slot and very moderated (almost shy) Chamfering. Does anyone know why diagonal Slots and not the typical straight one?
It Is very common nowadays to find Braking Pads with one, two or even 3 slots, moderate, or radical Chamfering (some until the back plate) what I find very interesting is the diagonal slot.
Best and thanks in advance.
My guess is that the slot is slanted to distribute the forces on the slot edge as the pad contacts the disc. Does it make a difference? Impossible to tell without sophisticated testing. My guess is that it’s a gimmick.
The chamfering does, in fact, reduce chatter when the pads and discs are new.
Noise suppression and heat dissipation. Must be a Ford car? Factory brake pads have the diagonal slot, which means so should the replacement aftermarket pads.
It is a technique to reduce squeal. Slots change the natural frequencies of the brake pad surface so it doesn’t squeal. You would like few symmetrical dimensions to break up the tendency to vibrate. Pads often have an arc in the pad design so a straight slot would mean that the radial location of the pad would have a different width of pad material from inside to outside. A rectangular pad might be better with a slant for a similar reason.
Cutting a slanted slot would be a bit of a pain in the neck, TRW wouldn’t do that for an OEM part unless it really had an advantage!
Done to dampen vibration and provide a small outlet for some brake dust; both of which can lead to noise issues. A number of brake pads are manufactured like this including both OEM and aftermarket and it’s also common for some mechanics to modify pads that are not manufactured like this by beveling and slotting the pads.
TRW would do it if the diagonal slot is in a big customer’s purchase specification. It is possible that TRWsold the customer on this feature, though.
It seems like a slanted slot across the face of the pad would cause the pad to tend to move upwards or downwards in its cage during braking. Maybe that slight up/down movement is what causes it to have better anti-squeal qualities.
Amazing! very interesting responses, FYI: the part is for an Audi A4, the most interesting part is that we had an OE Pads (No way it is TRW) and it was flat! and the one from TRW had Slots and Chamfers (diagonal ones.). So now we are starting to think (thanks to some of your comments) that the diagonal slots might be done to conduct the dirt, heat, gas, salt, water etc, outside of the contact surface, simulating the small slots made in some “performance” disks. Oooor… as one of the guys in the office said it is to have a better sales argument! 
Also keep in mind that EVERY brake pad manufacturer has their own specific “brew” of friction material. All react differently and require different features to perform. Car makers don’t usually specify things like slots and chamfers, they specify performance, noise, wear and the like.
Thanks!