Topic: Drilling Rotors

[Killer Canary]

I've been meaning to try the rotary table method for seven years now.

[MRieck]

I think I'd still slightly countersink them, it'd involve changing from your drill bit to your countersink bit as you do each hole, (unless you've set the discs up on a rotary table) but I doubt that rubbing a bit of sandpaper over them is gonna do much to remove the burrs sitting below the level of the disc.

I'm sure I've read somewhere that slight countersinking reduced the incidence of discs cracking, and the holes retaining water, which reduces braking effectiveness. I agree with Al that after drilling all those holes the last thing you want to do is spend any more time on the drill press, but if you've gone to all that trouble, then you may as well finish it off properly?

Honda discs had a "glazing" problem which reduced their effectiveness, so we would often break the glaze with some wet and dry sandpaper, which reduced the squeal, and helped them stop better, and some guys had cast iron discs fitted, which made an enormous difference. Cheers, Terry.  

I have a full Brembo system on my FJ and the holes are countersunk on the floating rotors.

[schneider419]

yes, drilling the rotors is a good thing. i did that on my shifter kart, and had a lot better feel when i used the brakes. i guess what happens is when you apply the brakes a gas and brake dust builds up between the brake puck and disc, and reduces the braking. the holes give all that a place to go and the brakes are more consistant. it works at 115mph i guess it also works at highway speeds.

[SteveD CB500F]

So does anyone have a template for the different sized disks?

I'd like to write a FAQ based on this discussion, but without a/some template(s) there's no closure.

[SteveD CB500F]

This was provided by Pumski some time ago and is in the FAQs, but we only have a template for the 400F

http://eindiancompanies.com/howto/howtorotor.htm

[dusterdude]

anyone interested in getting rotors drilled contact nate houser at nhouser@yahoo.com.he charges 75.00 to do them.

[eldar]

Does someone have a drilled rotor that they could make a template from then scan in? This is a good upgrade and does not require that a person go through hoops to do it.

[ProTeal55]

I agree with Eldar.

All that I would need to do this would be a basic pattern of what holes need to be drilled where on the rotor..

[Alan F.]

Here it is, it's in two parts that must be printed and taped together, as well as the orighial instructions from the e-mail.
Thanks again to Daren P. for sending them to me years ago!

[Alan F.]

I forgot to mention that this is originally for a cb750 rotor, but may work on others as well.

[ProTeal55]

What size holes ??

[Alan F.]

I used 1/4 inch holes, but I've heard of using up to 1/2 inch.  it depends how you want it to look, I modified the pattern for four rows of holes instead of three...so 1/4 inch holes are fine for me. With three rows you might want to go larger, just draw a full size rotor and overlay the template, mark the center of each hole, and starting small, draw in the holes until you find YOUR ideal size.

[ProTeal55]

Sweet - 1/4 it is.
I would rather have the rotor stronger , and have less chance cracking then have more holes just for looks. Brakes is the one thing I don't mess around with...

Another Question ,
What brake rotors are inter-changeable on the CB's ?
Better yet , which rotors would swap onto my 1972 CB750K without any modifications ?

[eldar]

Yeah this will work just fine.

I think any caliper from 71 - 76 at least should be interchangable.  K calipers that is. you may even be able to use 77 and 78 calipers.

Rotors too.  77 and 78 masters are different so are the f brake system.

[ProTeal55]

Cool - Now I can go get another rotor to drill , and still ride the bike.

I am all about zero downtime on projects , especially with the Chicago winter knocking on the door...

[eldar]

Ahh you people dont know what winter is! Come to north dakota in january. We may not get as much snow but then snow is not the bad part of winter. We get weeks where our high forthe day is -10 to 20 degrees WITHOUT wind. When windchill is added in, it is about -50. We ALWAYS have wind. Our problem is that we are next to canada!

[Bob Wessner]

"We get weeks where our high forthe day is -10 to 20 degrees WITHOUT wind."


Now there's a grim thought. Our occasional dip into negative territory here Mich. is starting to look good. )

[eldar]

When they build around here, they use the same materials that they would in alaska and canada. If that gives you an idea.

[Dennis]

Come to north dakota in january. ...... We get weeks where our high forthe day is -10 to 20 degrees WITHOUT wind. When windchill is added in, it is about -50. We ALWAYS have wind. ....

Invitation DECLINED!

Emphatically DECLINED!!

I have spent enough time in upstate New York to know what cold, windy winter weather is like. Would not want to spend every day in it!

[Surly]

Vintage Brake has some really good tips on making your brakes work. All they do is brakes for old bikes and they cater to racers as well as street squids like  us. Check out this link http://www.vintagebrake.com/tips.htm
I found it very enlightening. There is also a page threre with reccomended MC ratios to help get that right. Read the disc tips before you drill your rotor.

[Chris Liston]

I have 2 rotors that could use some resurfacing.  One is scored and the other has a highspot on it. Would a Honda dealer be able to cut them? 

Also, do we have any templates for drilling them too?

[KB02]

Someone posted a template somewhere here. I know cause I downloaded it and drilled my rotor. 

[crazypj]

 I doubt if any Honda dealer will touch resurfacing.
Your best bet would be to find a machine shop with a grinder set up for surfacing rotors. (rotary grinding, surface grinders can only do one side and I think they may contact the rivet heads)
 They are very hard and the normal brake lathes in automotive shops will probably screw them up completely ( unless they have brake lathe set up with a grinder?)
PJ

[Zane]

Chris, I drilled out my 400f rotor this winter.  (I think it's smaller than your 550 rotor(s).)  Regardless, I found the info at this site somewhat helpful.   

http://eindiancompanies.com/howto/howtorotor.htm


I “used” the template at    http://www.eaglescall.com/images/cb400f_disc_template.pdf

I quote “used” because I was lucky enough to have access to a heavy duty, professional rotary table, and I didn’t really need to actually physically use the template so much as just use the degrees and layout numbers and dial them in.  I tell you this even though this template is for a slightly smaller rotor than yours is (are) I think the principles are the same.

The tools worked very well for me, but a few of the holes had a burr or two (no doubt caused by my inexperience).  So I took a very fine and flat knife sharpening stone and kinda honed both sides of the rotor.  That made it smooth.  I’ve put a few thousand clicks on the rotor since I drilled it, and it seems to have become a lot more smooth and shiny with use.

From my limited knowledge it might be that a Blanchard grinder is the best way to deal with an uneven rotor.  Blanchards are big suckers with a large stone and a rotating bed underneath.  (I’m not suggesting you buy one - but this old one for sale on ebay has good photos so you can see how it works.)

http://cgi.ebay.com/BLANCHARD-GRINDER-NO-11-ROTARY-SURFACE-GRINDER_W0QQitemZ7611167567QQcategoryZ45021QQcmdZViewItem

It’s also possible to set the rotor up on a lathe, and then to use a grinding tool to even it out.  Depending on where you live this might be the best way to go.

My approach was to just get another rotor.  Excellent used rotors are so cheap on ebay ($10.00) for the one I used.  I bought one to drill, even though my original one was okay.  The one I bought was hardly used.

I think it was a very worthwhile mod for me to do.  Although I’m anticipating a problem or two going forward, the stopping power of the rotor is unquestionable better in wet conditions.  That alone is reason enough for me to do it. 

Plus I like the way it looks -

However you decide to go - the best of luck with it ....

[crazypj]

 Thanks Zane,
I could not for the life of me remember the name, Blanchard grinder
Didnt want to try and explain tool post grinder but its probably the easier option.
Drilling rotors at home isnt a problem, just get a drill press and use low speed, 250~300 rpm, takes a bit longer but you dont have to sharpen/replace drill bits
 Cheap one from Harbour freight is more than adequate from stuff I've read on other sites.
Brakes work better and are less likely to get damaged by material in pads as the holes tend to allow foreign objects to come out of pad material (make sure edges of holes 'overlap' slightly) If you have a piece of paper and a compass you can mock up any pattern you want, only need to do a minimal amout of math to find out circumference of the hole pattern ( dont forget the hoes will make this slightly bigger, so dont try and start right at the outside edge, come in at least 1/2" for 1/4" holes)
PJ