Technical Disc brake rotors

I will be installing a Speedway disc brake kit on square back spindles, 11.750 dia. In looking at rotors I don't see any witness of balancing, they actually don't need it?

 

Too>Check balance=Put rotor on spindel with no lub in bearings/just WD 40 spray is enough.Do not run spindel nut down=just bearly finger it home= so all spins very free.
Spin rotor and,look were it stops!, Mark with a little chalk when it stops at the top;spin again an let it come to a stop=again mark; do that 3 or 4 times> If all the marks are on the same side=it is not balanced; if marks are all over the place around,=it is balanced .
You can,if it is not balanced, drill a little on side that is down> when your marks are all up=go slow in small amounts; tell your new chalk mark test,show them all around vs all on same side.
When brand new,they are balanced,but after recut,or clip Wt. falls out,nolonger.

 

In my 50 years of running an auto repair shop my shop has replaced literally thousands of brake rotors. Never once have I had an issue because the rotor was out of balance. My advice is install said rotors and don't worry about it.

 

I’ve never balanced a drive shaft I’ve cut

 

On "some" rotors you may notice small clip-on "weights" in small ribs on the rear, inner parts of the rotor. You may also notice small weights clipped onto the ribs in the center of the rotors (cooling fins).

I built my own brake ***embly for one of my cars, years ago. I clamped a spindle in my vice and started my way to making caliper brackets.
I noticed that the rotor that I was using kept rotating on it's own. I stopped and messed with that rotor. I thought it odd that a single plate (thin) rotor could be out of balance !?

I took a "center-drill" and drilled small holes in the outer periphery on the diameter until the rotor stopped, stopping at the same (heavy) location every time I spun it.
I use a VERY thin grease on the bearings so it was as free as possible to spin.
I balanced both rotors the same way.



Mike

 

I had mounted one rotor and was playing with it before I posted, couldn't believe that I couldn't find a heavy spot. No added clip on or in between fins weights. Not sure if I want to do any holes or slots yet. Thanks to all..