Rotors - Drilling and Slotting?

[sparky961]

Since there are quite a few people here that seem to be into racing and such, can I get some opinions and advice regarding drilling and/or slotting aftermarket rotors?  I have access to a more than capable industrial CNC machine to get it done.  Is it to be attempted?  What geometry to use?  Vehicle is a mid size pickup, and the reason for wanting these would be to improve hard stops from high speed and long distance "mountain" braking.  Commence the education....  My thanks.

[Powder Keg]

It seems like this was brought up on one of the old motorbike forums. I think they determined it was more for looks than anything. I was going to mill some sweet looking slots in the rotors on my Kawi but decided against it after all the reading.

~Wes~

[RussellT]

I don't think this is entirely for looks.  There are two issues, one is clearing water from the surface of the disc when you put the brakes on, and the other is keeping the discs cool.  I think the grooves you see on motorbike discs are designed to cope with the first problem and drillings are designed to cope with the second.  However drilling through the disc reduces the friction area so I don't think it would improve overall braking performance.  Lots of car discs are radially drilled (or cast) to improve cooling but that wouldn't be practical with an aftermarket disc as it wouldn't be thick enough.

The cheapest upgrade to brakes for racing is generally different pads - but some of those don't start working until they're warm.  It's worth checking who made your existing pads - aftermarket pads are not always as good as the original manufacturers.

Russell

[sparky961]

Thanks for the suggestions.  It seems this may be one of those "it depends who you ask" things.  I'll probably just end up going with one of the better OEM or aftermarket products.

[DaveH]

I've done some.
 
DaveH

PS. sorry it turned out a bit big  Fixed it 

[angus]

not sure as they make a lot of difference for road use.....

they do however, make breaking sound like a london tube train.... you can almost hear " mind the gap!!"

[sparky961]

I've done some.
 
DaveH

PS. sorry it turned out a bit big  Fixed it 

They look sweet, Dave, but could you quantify any real difference in braking?

[DaveH]

Sparky,
I'm very sorry I missed your post for some reason - apologies.

I have never used them on my cars, they were made for a guy who customises MINI's. I've done quite a few.
Sometimes more for show (I think), but he has said it helps the pads from 'glazing' in repeated heavy braking.

 
DaveH

[+ or - Zero]

This is only my experience, so it's just 'for what it's worth'.

I have a 2002 Ford 7.3 diesel pickup, it weighs just a couple of pounds under 8,000 curb weight and I often pull heavy loads with it. I put slotted drilled rotors on it and non fade brake pads --it now stops in about 2/3 the distance it did before with the stock Ford set up. If there is fade I haven't noticed it, but I also have exhaust brake and all the Banks gear lock transmission stuff (well actually every thing Banks could install was installed), and I don't race it, so possibly brake fade would show up under more adverse use, I don't know. Given that it has an anti lock system the comparison between rotors is probably a fair one in that max braking is the same no matter what I do with mashing on the pedal. And like anyone that racks some miles up that has come up on occasion.

I don't know about the wear factor but tomorrow I'll be having a new set of tires installed and all the brakes and so on will be checked --that's slightly over 40,000 miles since the new rotors and pads were installed. As far as I can tell they work as well now as they did after they got set in --a few miles & stops before they really 'came into their own' so to speak.

Anyway I think they are of some benefit, at least they have been for me. BTW, I bought the truck new and ran it as delivered for the warranty period then had the Banks stuff done, and made two trips up and back to Alaska pulling very heavy trailers, before I did the slotted rotor & brake stuff --the trips up and back got easier after I did the rotors etc., so I'd say it's been a reasonable test.

Zero.