Drilling Brake Rotors

I'm guessing a few - if not all - of you have drilled your rotors at some point (or at least though about it).
3 Questions:

1. I was wondering if you had to have your rotors re-surfaced after drilling.
2. For dual disk setup, do you just clamp the 2 together, or is this too much stress on the bit?
3. Should I countersink the holes with a larger drill bit?

Also, what is the best bit to use? I have a small drill press, but I don't want to have to crack off 10 bits before I get em done.

I've never done it, but had it done. I've also read a few posts on it and remember that it's not as easy as it seems. Eats bits.

This is a job for an experienced machinist with the right tools. I wouldn't drill my own rotors. But how much performance are you gaining? Won' it wear out your brake pads faster? If your intent is to improve braking I suggest using stainless steel brake lines.

DrJ said:

This is a job for an experienced machinist with the right tools. I wouldn't drill my own rotors. But how much performance are you gaining? Won' it wear out your brake pads faster? If your intent is to improve braking I suggest using stainless steel brake lines.

Click to expand...

My plan wasn't to swiss cheese the rotors - or for huge performance gains. I have dual discs on a fairly light bike, so it stops fine.
More cosmetic I suppose - But I figured with better pads, and the added cooling (and lighter weight) of a few holes, it'd be win-win (good cafe-style looks and some moderate performance gains).

This is what I had in Mind:



And Yes, I would also like to go for stainless steel brake lines - But this would be a little to no cost project - and that's the budget right now.

Think with this simple pattern, and with the small amount of material actually being taken away I would see any negative effects?
I would have figured it was a no-loss, Small Gain situation...

Well if it's mostly cosmetic then a home job would do. But don't the pros drill the holes in a swirl pattern for a smoother contact? I suggest a good quality titanium bit. Obviously a drill press is needed and use plenty of cutting oil to keep things cool. Use a counter sink bit to bevel the hole edges, don't use a bigger bit. That will chew up the edges.

I don't think countersinking the holes is a good idea. I'm sure I read somewhere that leads to accumulation of brake lining and road debris in the holes.
Take a look at this guys work, see what you think.
http://cgi.ebay.ca/HONDA-CB350-CB400-CB450-BRAKE-DISC-ROTOR-MACHINE_W0QQitemZ300102484421QQihZ020QQcategoryZ111111QQtcZphotoQQssPageNameZWDVWQQrdZ1QQcmdZViewItem

That's deadley... Can't scrape up that kind of dough though.

Ease said:

I'm guessing a few - if not all - of you have drilled your rotors at some point (or at least though about it).
3 Questions:

1. I was wondering if you had to have your rotors re-surfaced after drilling.
2. For dual disk setup, do you just clamp the 2 together, or is this too much stress on the bit?
3. Should I countersink the holes with a larger drill bit?

Also, what is the best bit to use? I have a small drill press, but I don't want to have to crack off 10 bits before I get em done.

Click to expand...

I drilled out two xs rotors when I grafted this setup onto my Norton.

http://dotheton.com/index.php?topic=386.0

It saved a bit of weight which is good but adding a second disk adds so much weight it's allmost pointless. I went with the twin drilled disks for the symetrical appearance first, performance second. Light bikes can do well with one good disk and modern caliper.

1- I didn't resurface the rotors- I did debure the holes with a small oil stone.
2- I did each disk individually, as once both were clamped or bolted together it would be hard to lay the disk flat. Not to mention being harder to drill through with smaller starter bits.
3. Not countersinking. Just dress/debure the holes.

I used a 3d drafting program to generate the pattern I used and carefully marked the centers with a center punch. The pattern I used swept the complete pad area with the edges of the holes so the disk would wear evenly. I then drilled the holes out using steeped sizes- starting with apx 1/8 and finishing up with apx 1/4" diameters.

It was a long and tedious job. Rig up a resevoir of oil that you can control the drip rate with - little plastic dollar store clamps- guide a hose with a coathanger to the drilling area. This helps preserve your drill bits immensly.

Let me know if you want a pattern done tha you can print and use as a template.

c

I am gonna take a wack at drilling my CB450 disc.
The way I see it as long as I take things slow and use lots of oil I should be ok.
I am not looking for anything crazy, just wanna add some holes for looks more than performance..

P.S -->
You can get a completely custom stainless brake line made up (fitting to fitting) for around $45 from HEL-USA.
I had them make me one for my CB450 and it came out perfect...