Measuring rotor spacing correctly

[chickenStripCharlie]

How do you measure this correctly?
I'm doing this for rotor adaptors, so obviously the rotors arent on.

I used two Al plates, same thickness as rotors to simulate rotors. And I got 135.5-136mm. However, it's obvious on the used calipers that the inner pistons are a little further out on the R side than the L side.

I compared this value to what I found on this chart for a 2000 Gsxr750 (should be same as my '99 forks) and the value is 132mm center to center.

Adding half rotor thickness to my measurement to get center-to-center you get 136+4.5=140.5mm

That's 140.5-132=8.5 mm difference. Thats pretty significant.

What do you suggest I do to get a more accurate value?

Have all my rotor adaptor dimensions figured out except this one

 

[chickenStripCharlie]

Edit: I just remembered, i had the rotor surfaced milled 2mm to pull them apart, so that accounts for a majority of that difference.

Without getting new pads .... am I safe in finding the centerline of the caliper and just assuming the rotors will later follow that centerline??

Thanks!

 

[chickenStripCharlie]

Ok, measured caliper outside width and inside width to find the centers and got 138.5mm

Taking away 4mm for the milling that's 134.5-132= 2.5mm over the chart.

That's 1.25mm difference per side against those numbers in that chart. I think I'm fine with that. Should be all good

... I dont know why I come up with answers sometimes right AFTER I create a thread.

 

[TresCuatros]

Where did you find that chart at? I'm curious if it exists for other brands as well.

Glad you sorted it out so quick!

 

[chickenStripCharlie]

Where did you find that chart at? I'm curious if it exists for other brands as well.

Glad you sorted it out so quick!

It was on some SV650 forum. Guys doing GSXR swaps had compiled it up. From my research, i could not find a similar one for other manufacturers .... and i searched quite a bit.

 

[crazypj]

Have you stripped calipers to check them? The pistons should be 'flush' with casting when fully retracted