just about to fit my nice new brakes, which way should the grooves on the grooved discs face? towards the front of the car at the top or towards the back? or does it make little or no difference?

cheers,

Ned.

Dunno the technical answer but I'd go for outermost part of the groove forward, so the pad is swept down onto the retaining recess in the caliper. If it's swept upwards I guess it'll be pushing up onto the retaining pins??

I had the same prob Ned and the general thought was grooves forward at the top. There should be a sticker on the discs tell you which side it fits????

found this pic of the near side front.

Image deleted by owner

Image deleted by owner

[Edited on 6/3/06 by donut]

i was actually just thinking the opposite so that the brake dust would be thrown out from the disc rather than pulled towards the centre. but then i hadn't thought of pressure on the pad pins..

Ned.
Rescued attachment IMG_1856b.jpg

always helps to read the instructions..
Rescued attachment IMG_1859b.jpg

I was about to reply that I thought Donut had them the right way round when you posted the instructions which I rememberd using when I fitted them! At least my memory wasn't too bad.

Well there ya go! some say that way, some say this way!!!

What a crazy world we live in

I'm buggered if i'm changing mine though!!

mine are wrong, to no ill effect

i'm pretty sure ap racing's website says donut's way, and that's why we all went with that at the time.

it can't make that much difference though can it?

tom

Drivers side the EBC way.




Cheers


G

I thought it was different for the drilled ones to the ones with grooves only.

Some say one way, some another.

With them the way EBC say to fit them (outer edge of groove facing up on the front edge of the disc) any crap in the grooves is thrown out. The other way around, the grroves just trap dust and dirt and dont get rid of it. No idea why you want to fit them the other way around to be honest, but I guess I cant argue with the brake manufacturer eh?

David

I thought grooves pointing forward were more agressive and noisier.

After searching Yahoo for images it seems racing cars have the grooves facing forward and road cars facing rearward, maybe this supports the noise and harshness theory?

[Edited on 6/3/06 by MkIndy7]

depends if the groves go to the outside edge or not, if they do its to get rid of water quickly so groves pointing back, if the gove dosnt go to the edge pointing forward to make braking better.

or point them forward to wair them out fast or back slow lol

Check the manufacturers recommendations

(If you know who the manufacturer was, of course)

We recommend that our discs are fitted in the same way as the EBC ones shown (also the same as Ned's instructions) - i.e. make sure the curve is concave in the forward direction.

Ned - you have a U2U (ref' SPA gauge)...

From the braking assignment carried out a few years ago it shouldn't matter which way around the grooves face from a brake efficiency viewpoint.

Dust build up is unlikely to have been considered important to direction - the speed of airflow is likely to dislodge any particles before buildup occurs. That is unless it hasn't been shaken out along with my fillings by the constant thudding of the wheels on every pothole in this god-forsaken road network of ours....

The grooves merely allow the gas that the pad material releases when overheating to escape, preventing it from acting as a cushion between pad and disc - otherwise known as brake fade.

These are my RedDot 6 Groove fitted the way the instructions said, I had a few people query why they are fitted that way and ended up asking RedDot if it was correct and they said it was, but their 20 & 40 groove ones fit the other way. I guess most manufactures have their own way and reasons

(the front of the car is on the left)

Ned, opposite way to Andy-mates (aka donut)!

Fozzie

well, while everyone has been debating it i have fitted them all
Rescued attachment IMG_1860b.jpg

more..
Rescued attachment IMG_1862b.jpg

Another spanner to throw into the equation.

It might be to do with the shape and number of the grooves cut in the disk as to which way around there to be used.

I've got 36 square cut grooves going the opposite way to those last pictured (alfa147's) but they are rather "noisy" i.e you do hear a slight grating noise as they are applied lightly.

On the kit car we've got (probably 18) grooves going the same way but with rounded edges (like greenstuffs) cut with a ball end cutter and theres no extra noise at all compared to standard.

I'd hate to think the 36 groove versions would make and more noise if the grooves went the other way.

[Edited on 6/3/06 by MkIndy7]

Going back to my point about pad retention...........................

If the brakes make a "grating" or slight vibration under light braking, then the pads are vibrating.

If they are, then they want to be pushing the pad against an abutment if there is one.

Now different calipers support the pad in different places.

Those with std sierra calipers can do what they like cos the pad is totally supported on abutments, but on my RaceLeda calipers, the abutments are on the "hub side" of the caliper, nearest the disc centre, hence "pulling" the pad inwards.

Looking at your Hi-Spec calipers Ned, they don't look like they have abutments at all, so I guess it doesn't matter!

quote:

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Originally posted by NS Dev
Going back to my point about pad retention...........................

If the brakes make a "grating" or slight vibration under light braking, then the pads are vibrating.

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Yea, I wasn't saying that they won't vibrate, just that those using aftermarket calipers like me might (and I don't think it's really an issue, but...) consider that the pad vibrating against a little retaining pin is probably not as nice a situation as it vibrating against a solid machined abutment.