Highway Robber

I bought a set of grooved discs that were actually plain discs that had been grooved by a specialist. However after braking at high speed I'm of the opinion that they're too soft and my braking scares me sometimes.

So I've looked at my new brakes (now worn in for 4,000 miles) and have noticed that the grooves start near the inside edge and sweep backwards to the outer edge but do not actually go to the outer edge.

I thought the grooves were to act as a trench taking away brake dust and hot air, therefore if they don't go to the edge of the brake they won't do this.

Have my brakes been made wrong?

[Edited by Highway Robber - 9/28/2002 8:28:00 PM]

lanky

I believe the grooves are there primarily to get rid of hot gas build up on the face of the pad, not dust. The grooves don't actually act as a channel to sweep all this away, so don't need to go all the way to the edge. Don't worry...everthing's fine!

Highway Robber

Cheers lanky!

At high speeds when there is a buid up of hot air, the air is trapped in what are primarly "troughs" and not grooves, because it can't escape.

If the grooves don't go to the edge how do they get rid of the hot air?

[Edited by Highway Robber - 10/1/2002 6:07:12 PM]

Highway Robber

Anybody else got any thoughts on this?

Pavlo

Grooves, holes and other "features" on the disc surface are there to (primarily) release the gas that is formed by the pad material vapourising under braking. The amount of gas is very small indeed, but enough to reduce the friction of pad to disc.

Don't forget that the pads also have a groove in the middle, so there is very little time (if any) during the rotation that one or other end of the groove isn't exposed, and even if it weren't I very much doubt there would be enough gas to fill the groove completely.

Paul

griffm

I believe the grooves are longer than the width of the pad thus allowing the gasses to vent at each side of the pad.