Custom brake rotors

[Geezer]

I have a connection with a place in Taiwan that will make all sorts of stuff and one of their products is brake rotors.

Anybody think these are worth $200 a pair?
http://www.oregonmotorcycleparts.com...BrakeRotor.JPG

I'm temped to order a pair for as a sample for my bike but I'm concerned about the loss of surface area.

Geezer

[DGXSER]

Yep plenty of venting space. Looks like alot more holes than metal to me. See if they have applied them and have any stopping distance information available.

[Geezer]

The company that makes them is pretty much just a CNC machine shop. They make stuff that people will buy. This style is popular on sport bikes but I know nothing of how well they work. I'm sure they would shed water well but I'm more concerned about dry performance.

Geezer

[psycoreefer]

They seem to work fine on the sport bikes, some even come with them stock. I personally wouldn't pay 200 bucks for them, unless there was something wrong with my stock rotors but to each his own...

[cywelchjr]

Actually EBC has replacement rotors for our bikes that are supposed to be plug and play. If I have to change out my rotors I may well get them just for the reduction in unsprung weight. They also claim increased stopping power but I'd be afraid I'd lock up the wheels all the time if they worked better than they do.

That said, I do like the look of drilled rotors, going to be putting crossdrilled and slotted rotors on my Camaro before it goes back on the road this winter.

[tw1980]

Break rotors have come along way in 30 years.My guess is these are made of material that can withstand much greater temperature than our stock rotors and if I remember right the EBC rotors were more expensive than these.Thats why I drilled and resurfaced my stock rotors.Lighter rotors means less rolling mass which = quicker acceleration and breaking right?Also what about the unsprung weight thing?Terry

[DGXSER]

My only thought is that the rotor weight on these bikes has to be less than 1% of the weight. As far I have read or know, the purpose of drilling holes or slots, other than style, is to create a vent path to relieve the heat and gases that can build between the pad and the rotor. But that is ALOT less surface area to create the friction that is the stopping force. Just my impression from looking at them.

[tw1980]

If I remember right from physics class.I don't think reducing surface area decreases friction if the pressure remains the same.But that was long ago.

[fredintoon]

If I remember right from physics class.I don't think reducing surface area decreases friction if the pressure remains the same.But that was long ago.

Hi TW,
"Friction is independent of surface area (for low speeds)" From a long ago 5th form mechanics class.
Thing is, those candyarsed fretworked rotors will only be changing the bike's looks.
To improve the stopping power you'd need a modern multi-pot caliper to go with it.

[DGXSER]

If I remember right from physics class.I don't think reducing surface area decreases friction if the pressure remains the same.But that was long ago.

Well, that is partially true, as in the amount of friction on a given surface area is dependent upon the pressure applied and the friction factor of the surfaces the force is being applied to. However, the total stopping force being exerted to the machine will be dependent upon the total amount of surface area that force is being apllied to. The pads are only so big, and with less rotor to push against, as in more holes than metal they are contacting, the less total friction being created and therefore less stopping power.

Think of it this way, If I ask you to pick up a sheet of drywall without grabbing the edges, only pushing against the faces of it. I've had to carry them this way many times. Now only use your finger tips and not your entire hand to do it, or just half your palm perhaps. you can still exert the same pressure/force against the surface of the drywall sheet, just alot less surface area.

[cywelchjr]

Well, that is partially true, as in the amount of friction on a given surface area is dependent upon the pressure applied and the friction factor of the surfaces the force is being applied to. However, the total stopping force being exerted to the machine will be dependent upon the total amount of surface area that force is being apllied to. The pads are only so big, and with less rotor to push against, as in more holes than metal they are contacting, the less total friction being created and therefore less stopping power.

Think of it this way, If I ask you to pick up a sheet of drywall without grabbing the edges, only pushing against the faces of it. I've had to carry them this way many times. Now only use your finger tips and not your entire hand to do it, or just half your palm perhaps. you can still exert the same pressure/force against the surface of the drywall sheet, just alot less surface area.

Correct, but the reason nearly all new MC rotors are drilled is because a non-drilled rotor can build up a thin layer of gasses under the pad under heavy braking, it take additional pressure to keep the pad pressed tightly against the rotor in this situation. The holes in the drilled rotor allow these gasses to escape out from under the pads easily which increases stopping power more than the loss of surface area decreases stopping power. In addition, the holes provide more cooling surface for the disks so they stay cooler meaning less outgassing from the pads in the first place. I have seen test on cars both with and without drilled rotors and generally stopping distance is greatly reduces with the drilled rotors, probably almost as much as SS brake lines.

[DGXSER]

Correct, but the reason nearly all new MC rotors are drilled is because a non-drilled rotor can build up a thin layer of gasses under the pad under heavy braking, it take additional pressure to keep the pad pressed tightly against the rotor in this situation. The holes in the drilled rotor allow these gasses to escape out from under the pads easily which increases stopping power more than the loss of surface area decreases stopping power. In addition, the holes provide more cooling surface for the disks so they stay cooler meaning less outgassing from the pads in the first place. I have seen test on cars both with and without drilled rotors and generally stopping distance is greatly reduces with the drilled rotors, probably almost as much as SS brake lines.

Yep, agree completely on the gasses and the reason for slotted and or drilled rotors. Most car rotors are slotted for the gasses vs drilled (the ones I have seen and used anyway). Somewhere there is a breaking point (no pun intended) of increased performance from limiting the gasses building up and the decreased area for friction to be applied. I do not claim to know where that point is, but these look to me like thay have gone passed it. Thus the reason I asked for the performance data.

[xschop]

Custom rotors

I reaserched lightweight rotors a while back and found that VFR rotors and CBR rotors of these years are very close match to the XS Dimensions. You would have to take off 2mm from the rotor's hub diameter and drill out the bolt holes (6mm) to match the XS11 diameter (8mm) Would be an easy mod...Adapt some 6-pots and you are world class.
http://cgi.ebay.com/ebaymotors/Front...Q5fAccessories

[Geezer]

I'll have a price in a couple days. I'm putting on a pair of R1 calipers so I'm more inclined to install a set of custom rotors sooner or later.

I'm looking to import them for a couple different obsolete bikes if I can get the price down. Unless I can get them out the door for under $130 a pair, then they're not worth bothering with.

Geezer

[Geezer]

Well guys I've got more info. This is turning out to be more of a project than I thought but I think I can pull it off.

Here's the rotor design I'm leaning toward right now.
http://www.oregonmotorcycleparts.com/images/rotor1.jpg

I could design the pattern myself but I'm not much of an artist or any good with CAD. I'd like to go with something like the 1980 rotors but with many more slots. If I designed it there would be a space between the slots about equal to the width of 1.5 slots and a half circle cutout on the outside edge in between the slots. If anyone on the list is good with CAD and would like to help with the project, I can come up with hardware to trade for their work.

The center would be black unlike the blue in the picture and the hardware that fastens the disk to the disk hub was left out of this picture to show how it fits together better.

The bottom line is the estimated price right now is around $120 a pair for the fronts and another $65 for a rear FOB Portland, Oregon. I'm going to get a sample set sent to me once the design is finalized.

Geezer