rotors and spindles

[blackbear]

a lot of you guys talk about 1 inch and 1.25 inch rotors or spindles. what is the difference and how and where do i measure the rotor or spindle.i have spindles off of a 87 but dont know witch ones i have.can anyone help me understand this.

[LostMy65]

I think it's the width of the area that the caliper presses up against.

[64shortbox]

The 1" & the 1 1/4" does refer to the width or thickness of the rotors. The 1" rotors were on the 6 cylinders & the 305 V8's. The 1 1/4" thick rotors came on the 350 CI and up trucks and were the heavy duty brakes.
You can't swap the rotors out without swapping out the spindles too if you want to go to the heavy duty rotors.
Hope this helps.

[Captainfab]

I just did a little online research. The difference between the light duty spindle and the heavy duty spindle is in the size of the inner bearing. The inner bearing surface of the light duty spindles measure aprox 1.250". The heavy duty spindles measure 1.375"