Drilling Brake Rotors

I bought a dual disc setup to put on my 80 650 LTD. I thought the discs I was buying were drilled, but they were not, so I am trying to drill them in the pattern of the single disc that came on the bike. The first pilot hole using a regular carbon drill bit went right through. When I tried to drill the second pilot, the bit went flat. I had several 1/4" bits to use for pilots, so I tried another...nothing doing. I then went out and bought a cobalt bit, which I have had good results with in the past. I bought 1 1/4" for pilots and 1 5/16" for the big holes. The pilot bit did nothing and the big bit went flat after only getting half way through. I am using a drill press, and oil, so I can't figure out what the problem is. Is there another type of drill bit I should be using? It took me most of the winter to get my drill press working and I really want to get this done before spring. If anyone knows what I am doing wrong please tell me.

try 1/8" bit for pilot hole turn speed on bit down dont push so hard ,use lots of oil to keep bit cool.its a long process:whistle:

The 5/16" bit hardly even made a dent! I turned lightly on the handle and used lots of oil too.

buy a bunch of good bits,youre gonna go through a few.once you drill all your 1/8 pilot holes the bigger holes should go pretty easy!goodluck,happy wrenching!

Those cobalt bits are $10 a pop. I was hoping I wouldn't have to spend 100 bucks for drill bits. Do you know of any better kind of bits?

get some good hi speed steel bits shouldnt be more than 2-$3 bucks each for the smaller ones at menards or someplace like that.where are you located at?

I'm in NY (the Bronx right now, but I live in White Plains)

Correct me if I'm wrong, but there are such things as diamond tipped bits right?
Scott

well the rotor surface has been heat treated when the brakes are applied, you will need a good drill press and cobalt bits, you need good coolant/ cutting oil also. I have never seen a diamond tipped drill bit, but it wouldnt work anyway, diamond does not like steel to cut anyway.
you might want to take it to a machine shop, they can get the drill pattern down perfect and they have the drills to do the job, also make sure to chamfer the holes too

You sure those disk rotors are not stainless? They sure seem to be rust resistant, although I have not checked to see if a magnet will stick to them, and stainless steel is awful hard to drill.

Post edited by: steell, at: 2006/03/06 17:59

You should have bought the front end off my 82 750 LTD even with gas you will be saving $$$ ,, Disc already drilled out .. duel brakes Good Luck .. :whistle:

you are using a drill preess arent you? i guess i should of asked you that!ive drilled a few sets of rotors im pretty sure the rotors are just steel and they will rust,carriers are aluminum.