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Reply to "Front drum to disc conversion."

No pictures, Al.

I'll try this again-

@ALB posted:

@DannyP and @dlearl476 (sorry, forget your first name?)- When I was drilling holes in my type 3 backing plates awhile back I weighed a type 1 piece bare (without the cylinder but it was a little dirty)- 1020 grams- 35.979 oz.  The type 3 backing plates I'm using weighed 1284 and 1285 g and was able to get them down to 850 and 849 g.  There's over 200 holes, as well as a lot of profiling of edges.  As you can see, I even reworked the block that holds the adjusters (as well as drilled out the middle- there's no reason for all that metal to be there!).  It really is a labor of love- I didn't come up with the complete pattern the first day- and to set up each time (on a small  drill press without a rotary table) so it's somewhat close to concentric takes forever. I don't want to think of the number of hours invested in just the backing plates and it's not even a pound reduction per side.

lightened type 3 rear backing plate

I believe that holes in the rotors improves stopping power as well (letting gases escape and improved rotor cooling and all) but it does have to be balanced with the minimum mass needed for the weight of the end of the car it is controlling.  There are several different hole patterns that have been proven to work- I believe the theory is to cover the whole rotor so no area gets hotter than another.  The holes need to be chamfered to help prevent cracking and the more air you can duct to them the more effective they will be.  Some believe that holes do nothing on the street and carved slots (just down to the minimum thickness of the rotor) are more effective.  What I think is really neat is the wave patterns now being used- this is a rear Corvette rotor- I'm really lovin' the way they carved up the hub as well!

lightened rear corvette rotor

One last thing to leave you with- an aftermarket rear rotor for a Suzuki bike by MM Racing- only 375 g (13.22 oz) - available with optional fully forged titanium bolts for further weight savings (only a paltry $69 option)!  I just noticed the maple leaf- I wonder it they're Canadian?  Just looked it up- Florida.  There's probably more I want to say here, but this is enough rambling for now...

Lightened Suzuki rear rotor MM Racing



Images (3)
  • lightened type 3 rear backing plate
  • lightened rear corvette rotor
  • Lightened Suzuki rear rotor MM Racing