Ive seen in in other vids, but still dont undestand why they do it. The press the brake pedal on the straits, before they really brake the car. Could it be to test the feel of the pedal, or to keep the pads to temp, something to do with the servo...........any idea??? [YOUTUBE]x6UXHqngdxI[/YOUTUBE] [YOUTUBE]zUU0aW3yyMc[/YOUTUBE]
i cant see the video but iirc its a technique to keep the pad close to the disc to avoid "knock off" ive seen it in a fair few best motoring videos. on a long straight their left foot will hover over the brake pedal, it looks like they give it a stap
Interestingly the new seat leon does this automatically in wet conditions to keep the pad closer to the disc!
Its too prevent pad knock back. EDIT: just seen Matts post I think its knock back not knock off! lol!
Knock off is usually associated with warped discs?? Never seen it being done as a matter or course, though after some warp speed, it might be something you'd consider? Yet he was doing it from the off in the F50... Vid 2 - trackday race, with a lap countdown?
If hes used to driving other things then it might just be something thats programed into him if you know what i mean. Like one of the V8 supercar drivers was giving demo rides in the road car version of his Holden race car, and on the video of his feet he was still driving it like the race car, double clutching on the down shift but only into 3rd, keeping the clutch dipped through 2nd and going straight to 1st and so on, was pritty good to watch.
Its knock off, when hitting curbs hard it can cause the pad to move away from the disc and cause a long brake pedal. So a quick tap will push them back in again.
My understanding is there's 2 reasons for this- 1. Its only really used on circuits with long straights and race cars with very good brake cooling ducts. As the car is travelling down the straight the brakes start to cool which reduces the brake fluid temperature and therefore the pressure in the system. This then moves the pistons back slightly, increasing the pedal length. 2. This applies more to vintage racing cars and road going cars where the hubs and associated components flex during hard cornering which physically knocks the pads and pistons back slightly.
As stated previously it's called 'knock off' it happens in lots of race cars in-particularly heavily braked cars. happens mainly from hitting curbs, have you seen the slow Mo's in F1 where they ride the curb and the wheel distorts? this moves the disk around in between the calipers and pushes the pads back. Also as seanlazyass said it happens as the braking system cools on the streights but this is less of a problem and usually only happens when youv'e got ****ty old pads in with not much meat left on em!
