Topic: Drilling Rotors

[Alan F.]

736cc, you've got a PM.  that's a wild bike and I've got some wheel questions.

[eldar]

One comment I saw a while back said that it decreased initial braking action somewhat since there is less surface for the pad to contact. With dual disk, not much worry but those of us with the single might want to check on this.

[Jinxracing]

Cribbed this from the brakewarehouse.com Brembo FAQ page...some interesting food for thought. Especially the part about rotors cracking when the hole edges aren't radiused or chamfered properly. Yikes!

I’ve heard that cross-drilled rotors are prone to cracking. Are cross-drilled rotors prone to problems?

Some people prefer slotted rotors because of problems that came about when cross-drilled rotors first came to market. At that time, quite frequently, the holes were drilled too large, penetrating the cooling vanes and were not radiused or chamfered. The end result was that the rotor lost its structural integrity and tended to crack, so slotted rotors were developed. They do help dissipate the hot gasses, but not to the same degree as cross-drilled, usually lowering operating temperatures about 100 degrees. We always recommend cross-drilled unless you are particularly concerned with structural integrity. In some cases, only slotted rotors are available.

[Alan F.]

Hey Swoop, that's because the template goes over the rotor hub...the side of the rotor that mounts to the wheel hub, that's why it looks opposite.  But whatever pattern you like best, it's YOUR bike, you get to choose.

[Roscoe]

Does anyone know how to drill out the front and rear disks? Is there a pattern you should use ? And what are the advantages of doing so apart from looking good? I'm new to this.
Are they easy to drill? Cheers, Roscoe

[fuzzybutt]

you might want to try searching the forums before asking a question. there have been lots of threads devoted to this subject in the last couple of weeks

[Roscoe]

Sorry about that just though it might be qucker this way as there is so much info on the forum it could take a while finding it.

[kghost]

I remember when fuzzybutt was a newbie......


Just teasing ya Jeff.

He's just reached a point where the questions about a topic thats been beat to death drives him nuts.

We all get there eventually.

There is literally volumes of information in various topics about drilling out damn rotors and drums.

[fuzzybutt]

sorry about that roscoe, ya just got me on a bad day    pain issues

[neil10]

if u can't help keep quiet

[kghost]

if u can't help keep quiet

Said the guy with 100 posts.......

[fuzzybutt]

ahhhhhhhhhh it's all in good fun.

[Steve F]

Try this link from a post just two or three days old....
http://forums.sohc4.net/index.php?topic=31083.0

Regards,

[joeb]

Nice burn. kghost 

[Godffery]

   I'll post a pattern I made as soon as I figure out how ?
http://springvinmoto.com/gallery/album85/Twin_Disc_1

Godffery
http://tinyurl.com/yoelqb

[kghost]

Two words....Cobalt drillbits.

If you use high speed steel...we'll see ya in a couple years.

When I do mine I use an old rotor as a pattern....long as the diameter matches its just a guide.

Drill two holes and bolt the pattern to your disk.

[754]

High speed will work under the right conditions.. go slow, use coolant..

[kghost]

Use coolant, make a mess, take all day.....

[Roscoe]

Hey thanks guys for the help. No worries fuzzybutt. No offence taken. I'll let you know how I get on when I do it. Cheers and thanks again for the help. Roscoe

[turboguzzi]

Hello All

Would like to know if anybody's got a good and proven drilling pattern for front discs.

Bent one of the drilled/slotted suzuki discs I was running in my racer and manged to get only a non drilled replacement.

A dxf file would be best but can work it out also from dimensions/pics.

Thanks in advance

TG

[Kev Nemo]

Just looking for ideas. Also methods would be a great help (traditional drill, drill press,etc.) My main question is getting different sizes and layouts. I've read a post on cross drilling calipers by using a CAD layout-is there a simpler method?

[kghost]

Far as caliper drilling goes....

A flat worn out sport bike rotor of the appropriate diameter is what I used.

Drill the first two holes 180 degrees apart using the worn out rotor as a guide....

Bolt them together and drill all the rest.

Least thats what I do.....

No patterns...no guesswork...no line up problems...no wandering drill bits etc.

[Steve F]

kghost, do you have a favorite drill bit (composition) that works best for you?  What RPM works best?

I'm obviously not KGHOST, but the drills I would recommend would be of the COBALT variety, and short.  The length I used is called a "screw machine length" or "SML" and are available from just about any industrial supply.  I used water soluble coolant and about 500 rpm on a 5/16 bit.  Smaller bits could tolerate a bit faster spindle speed.

[kghost]

kghost, do you have a favorite drill bit (composition) that works best for you?  What RPM works best?

I'm obviously not KGHOST, but the drills I would recommend would be of the COBALT variety, and short.  The length I used is called a "screw machine length" or "SML" and are available from just about any industrial supply.  I used water soluble coolant and about 500 rpm on a 5/16 bit.  Smaller bits could tolerate a bit faster spindle speed.

Steve has it...COBALT...anythink else is a waste of time and money.

Be prepared for sticker shock...but ya only buy one.

[chopstar500]

I took measurements first, then did a full scale layout of the patterns in Microsoft Word (you can get very precise when you scale lines to the actual size) and then printed the patterns and applied them directly to the parts with some cheapo gluestick - then drilled the holes. I staggered the hole sizes (symetrically) and then finished them up with a chamfer bit.