Author Topic: Drilling Rotors (Read 69092 times)

Dougy Dougy Dune Buggy · « **Reply #125 on:** December 10, 2006, 10:04:06 AM »

Kevin, e-mail me and i'l' forward to you also
it's for a 400 four rotor, never counted the holes
though
DWYJ

dwyjr@yahoo.com

Tim2005 · « **Reply #126 on:** December 10, 2006, 10:38:31 AM »

Kevin, I think the swept look is neater- check this one out.

By the way, have you checked your email lately?

Cheers

Dougy Dougy Dune Buggy · « **Reply #127 on:** December 10, 2006, 10:45:53 AM »

Wow..nice pattern on that last pic!
how long did it take per rotor??
Thx
DWYJ

Tim2005 · « **Reply #128 on:** December 10, 2006, 10:59:30 AM »

Only took a few seconds... a couple of mouse clicks on Ebay! Must have taken somebody ages to drill it, 192 holes & every one is slightly countersunk too. The disc is noticeably lighter even.

kettlesd · « **Reply #129 on:** December 10, 2006, 11:29:14 AM »

Wow Tim - seriously nice lookin rotor!

Kevin400F · « **Reply #130 on:** December 18, 2006, 06:37:00 AM »

I played around a bit with paper and a compass, and came up with a "swept" style pattern of eighty-four 1/4" holes. I tried to upload a scan, but apparently there's a disc quota exceedance on the site.

Try this link:
http://us.a2.yahoofs.com/users/2VgxWgocaxwi/__sr_/fe1e.jpg?tkn=ph8drhFBt34GsO4m&saveas=400Fdisc-spiral_drill

Cheers,

Kevin

tmht · « **Reply #131 on:** December 28, 2006, 05:41:54 PM »

Quote from: Kevin400F on December 18, 2006, 06:37:00 AM

I played around a bit with paper and a compass, and came up with a "swept" style pattern of eighty-four 1/4" holes. I tried to upload a scan, but apparently there's a disc quota exceedance on the site.

Try this link:
http://us.a2.yahoofs.com/users/2VgxWgocaxwi/__sr_/fe1e.jpg?tkn=ph8drhFBt34GsO4m&saveas=400Fdisc-spiral_drill

Cheers,

Kevin

Kevin,
That link doesn't seem to work. Did you email that to Bud? Dave put together a template using a degree wheel, though I am not sure how many holes or what size. Also he got a line on something very special brake wise that either Bud (I'm not sure if Dave and Bud have spoken on this subject yet.) or I will tell you about soon.
Terry

Terry

Kevin400F · « **Reply #132 on:** December 28, 2006, 06:01:56 PM »

Hmm...not sure what is wrong with the link. I did e-mail it to Bud. I should send you the original paper via snail mail, since it was traced around a spare disc, and would be easier to use than trying to exactly scale the .jpg.

GroovieGhoulie · « **Reply #133 on:** March 23, 2007, 06:20:53 PM »

Can the brake rotors be turned if they have some scoring, or do they just need to be replaced? Are new rotors still available, like so many other parts?

Also, how prone are the rotors to warping if overheated?

I'm asking because last week when my 750F's rear brake seized on a ride, it got so hot that the stainless steel turned purple and blue, and the inside pad melted some, lightly scoring the backside of the rotor. I'm hoping it didn't warp the rotor.

Bob Wessner · « **Reply #134 on:** March 23, 2007, 06:35:19 PM »

How scored is scored? A pic might help. I know they are quite hard being stainless, so I can't say anything about turning them. I'm sure someone will have some experience there. If it is still on the bike, could you check for warping by attaching a wire pointer somewhere so it is just barely touching the rotor and slowly spin it see differences in distance between the pointer and rotor surface? You could try it at a couple of different places along the radius. Just a thought.

GroovieGhoulie · « **Reply #135 on:** March 23, 2007, 06:44:48 PM »

Rear brake:

Back of Front rotor:

Sorry for the bad pix. Was in a rush, ya know?

BobbyR · « **Reply #136 on:** March 23, 2007, 06:51:40 PM »

It is pretty hard steel. I sandblasted mine to see if I could get rid of the squeal, so I can tell it is hard. The one thing in your favor is that it is the rear, so if it is a tad warped it would not really effect you much since you should be using the front at speed anyway.

kettlesd · « **Reply #137 on:** March 23, 2007, 07:04:40 PM »

Can you catch your fingernail in those grooves? Ive definitely seen worse.

Steve F · « **Reply #138 on:** March 23, 2007, 07:10:38 PM »

I had a front rotor ground at a local Ducati shop a few years back and they didn't get it parallel, or warped it in the process of grinding it. The brake pulsates now, where it didn't before. I heard that grinding is the only way to go because they're stainless and pretty tough and thin too, making turing them in a lathe very difficult if not impossible. I'm toying with the idea of setting up a grinding spindle in the lathe to give it a go. The only major problem is getting the rotor parallel to the mounting surface of the center hub. I think that bolting it to a face plate should take care of that pretty well. If I should decide to do it, I'll post some pics.

GroovieGhoulie · « **Reply #139 on:** March 23, 2007, 07:15:48 PM »

Quote from: kettlesd on March 23, 2007, 07:04:40 PM

Can you catch your fingernail in those grooves? Ive definitely seen worse.

Can't catch and stick the fingernail, but instead of gliding over a perfectly smooth surface, it's noticably rough.

tsflstb · « **Reply #140 on:** March 23, 2007, 08:35:52 PM »

A while back a guy was on ebay offering a brake rotor service for old bikes. He had a rotary table and surface grinder set up and also did cross drilling. I sent him an extra rotor I had with the usual scoring much like yours. I think it turned out great. It's still within the service limits in the manual but I'm not sure how much material he took off to get rid of all the scoring. I haven't had the chance to mount it yet, but it should help get me slowed down a little faster when I do.

Zane · « **Reply #141 on:** March 23, 2007, 08:41:07 PM »

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 perhaps a business in your vicinity has one.)

I think Blanchard grinders are like Xerox copiers when it comes to jargon. Like when somebody calls a photocopy a "xerox", I think in the machining business that kind of grinding is called "blanchard" grinding.

http://www.bourn-koch.com/pages/content/blanchard.html

oldfart · « **Reply #142 on:** March 23, 2007, 08:44:20 PM »

Grinding is always preferred to turning. I wouldn't even have a car rotor turned. Grinding is done in many ways also, but the best way is what is called "blanchard grinding." This is where they grind on both sides, or in some cases simply register from the opposte side while grinding the other side, thus ensuring exact parallelness of both sides of the disc.

Steve F · « **Reply #143 on:** March 24, 2007, 02:12:51 AM »

Quote from: oldfart on March 23, 2007, 08:44:20 PM

Grinding is always preferred to turning. I wouldn't even have a car rotor turned. Grinding is done in many ways also, but the best way is what is called "blanchard grinding." This is where they grind on both sides, or in some cases simply register from the opposte side while grinding the other side, thus ensuring exact parallelness of both sides of the disc.

Blanchard grinding is fine, if you're only grinding a plain disc to a preferred thickness, but if you have an offset flange like on our rotors, there's the possibility that the ground sides won't end up on the same plane as the mounting flange face (wobble). If you're going to blanchard grind, the surface that is opposite the mounting face must be ground first to allow for a parallel surface which then goes face-down on the blanchard grinder's rotary table to grind the second face. It requires an operator with exceptional skill to set up and do it correctly. So you're at the mercy of the machinist's attention to details. If you DO end up with wobble after the disc has been ground there is a fix to that. Mounting the finished disc in a lathe with a face plate, you can then face off the mounting flange surface to flatten out the wobble. I had to do the fix on a rear rotor that had some wobble, and that took out the pulsing in the brake.

Terry in Australia · « **Reply #144 on:** March 24, 2007, 03:01:58 AM »

The K0-K8 and F/F1 discs are pretty thick, (unlike the F2/F3) so you shouldn't have a problem removing up to around 1mm of material with safety. (the actual minimum thickness should be cast into the disc carrier, from memory) Your disc looks pretty badly scored GG, I've only seen damage like that normally when there's been "metal to metal" contact, have you got any pad material left? Cheers, Terry.

GroovieGhoulie · « **Reply #145 on:** March 24, 2007, 09:25:51 AM »

Quote from: Terry in Australia on March 24, 2007, 03:01:58 AM

The K0-K8 and F/F1 discs are pretty thick, (unlike the F2/F3) so you shouldn't have a problem removing up to around 1mm of material with safety. (the actual minimum thickness should be cast into the disc carrier, from memory) Your disc looks pretty badly scored GG, I've only seen damage like that normally when there's been "metal to metal" contact, have you got any pad material left? Cheers, Terry.

Tons of pad left. A small swath of pad right in the middle must've gotten hot and melted, then re-hardened or something.

ofreen · « **Reply #146 on:** March 24, 2007, 10:39:06 AM »

Based on what you said about the depth of the scratches, and if the disc runs true, I'd clean up the caliper, install new pads and run it. Something similar happened to me many years ago on my '75 750F. I took off from work and rode 15 miles at 65 MPH. When I went to stop, the front brake lever came all the way to the grip. I got it stopped with the rear and looked at the front disc. It was purple. After cleaning out the caliper and installing new pads, I rode it. After a few miles, the purple was gone, the pads broke in and the brake worked fine (or as fine as it ever did.

). That was in 1980. Still running the same disc, just a little more conscientious about changing brake fluid periodically these days.

speedracer741 · « **Reply #147 on:** March 24, 2007, 04:15:59 PM »

The blanchard grinding service is still available on ebay. The braking surface is kept very parallel to the wheel since the outer facing surface of the disc is ground first, indexing off the mounting surface on the hub. Then the backside is ground indexing off the freshly surfaced and parallel outer face. This results in a rotor with consistent thickness and zero runout. If you will be having this done locally, be sure they cut the outside frist and clean the mounting surface of the hub with a lapping stone or similar to make sure there are no high spots. The machine I use is a Kwik Way blanchard grinder. tsflstb, when you gonna get that thing mounted? Your rotor only took a few thousandths per side to clean up.http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&ih=020&sspagename=STRK%3AMESE%3AIT&viewitem=&item=300092855130&rd=1,1

Raul CB750K1 · « **Reply #148 on:** March 24, 2007, 04:46:51 PM »

When I replaced the brake pads on my wife's car I saw that one of the discs had a big groove on it. I have no idea how was it made, but the fact is that the pad had developed a matching ridge. I really don't see the point of grinding the disc as long as the grooves are not deep. Just make sure you "break in" new pads until they adapt to the disc surface. Actually, the contact surface should be bigger this way....

Raul

tsflstb · « **Reply #149 on:** March 24, 2007, 08:50:21 PM »

Quote

tsflstb, when you gonna get that thing mounted? Your rotor only took a few thousandths per side to clean up.

Didn't realize you were the same guy that did the ebay auctions. You do good work. Glad it stayed in the "family".

I'll get the rotor mounted soon...got sidetracked when my transmission siezed up a while back and never got around to it. Working on getting my other bike running now so I can still ride while I tinker with the 400.

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Author Topic: Drilling Rotors (Read 69092 times)

kettlesd

tmht

kettlesd

Zane