Rear wave disc single sided swing arm - How to make your own speedo pick ups!

[MonsterDorf]

Just fitted an Armstrong rear wave disc to my S2R. Although it has the capacity to fit the speedometer pick ups it didn't actually have them. So thought about removing the ones from the standard disc but then decided to make my own. Recipe is simple. Take 4 Allen bolts 6mm x 10mm long. Grind/file down the head to 4.7mm then reduce the diameter to less than 8mm. Fit to disc using loctite. Test fit as clearances are tight. Your speedometer should be good as new and your bike has a nice looking wave disc to boot!

[Rowdy]

Good info. Thanks MD.

[Speeddog]

Got any pictures?

[MonsterDorf]

Good point, will take a couple & post.

[OzzyRob]

Just fitted an Armstrong rear wave disc to my S2R. Although it has the capacity to fit the speedometer pick ups it didn't actually have them. So thought about removing the ones from the standard disc but then decided to make my own. Recipe is simple. Take 4 Allen bolts 6mm x 10mm long. Grind/file down the head to 4.7mm then reduce the diameter to less than 8mm. Fit to disc using loctite. Test fit as clearances are tight. Your speedometer should be good as new and your bike has a nice looking wave disc to boot!

And you've reduced the swept area and reduced braking effectiveness in the process. Ah but it's all about fashion is it not. 

[ungeheuer]

And you've reduced the swept area and reduced braking effectiveness in the process. Ah but it's all about fashion is it not. 

Wave rotors have less surface area than a conventional rotor of the same diameter, yes.  But, my understanding is that the effective radius of the disc is at the centre of pressure of the pads, which is constant for a given caliper position regardless of disc geometry (assuming the full face of the pads is swept).  A wave disc of a given size has the same effective radius as the full disc of the same size.   So not less effective braking.   (But not more effective either). 

Any improvement in braking will come from the face of the pad being kept cleaner or from the cooler running disc.

Additionally, less surface area = less material which means a wave rotor should be lighter.  That's a good thing, especially so considering that this is unsprung weight.

But over-riding all that, the most important reason for going to a wave rotor is this:  They do look cool   .

[MonsterDorf]

Ok here are the promised pics. As you can see I simply ground down the height and width of a 10mm allen bolt and then bolted it to the pre-existing holes on the new disc. Torqued and loctite just to make sure.