Spotted these on EBay...

http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... K:MEWAX:IT

I can understand 4x4s having groved discs to disperse water and because alot of them dont hurtle along at 80mph but what use is it on a road car? Why dont the racers use them? Wont it wear the pads out really quick and cause wheel vibration/noise under braking?

How do you work out what you can drill/groove? I guess you cant just mill any old grooves in a set of discs?!

Just a few questions to get us thinking...

Grooved discs can provide more friction when gripped by the padsi believe, in my mind it makes sense that they may well cool better as well if drilled.

70's bikes often had cast iron discs and were drilled cos they were shite in the wet, needed the water to disperse anyway possible, so holes helped.

What use are they on a road car? Probably not a lot unless you regularly drive it like you stole it.

What use are they on a high performance/track car? yes they help disperse water and gasses, what gasses I'm not exactly sure. And they help to stop the pads from glazing. I'm sure anywhere trying to sell them will give a list of advantages as long as your arm.

I think they do wear the pads faster and maybe make a little noise but shouldn't cause vibration.

I notice in the ad that all discs are made to order, and would highly suspect that they'll pick a set of regular discs off the shelf and machine some grooves in them, and so long as the grooves aren't too deep there's nothing wrong with that.

2cv racers (at least, in the UK) use standard discs and pads, and they run all day and night flat out, with very few braking problems.

All the time...

I didn't realise there was another way to drive?

+1

Me too, every day!

Only time i've had/heard of brake fade from over heating on a 2cv is down long step hills (remember CZ Max ... pic)

I don't think they would wear the pad any more than normal, the discs will be flat/smooth on the faces, they look a bit cheese grater-ish but the holes/grooves in vented discs will (should) be flush.

when braking hard the friction material can get hot enough to gass or smoke this gas/vapour acts to keep the friction matrial off the rotor and so reduce the braking the pads are riding on a pocket of air so to speak

sean

and vented discs?

http://www.pp-2cv.be/EN/News/FreinVentile.htm