Garth S

There should be metal to metal contact on BOTH sides of the rotor.
Wheel studs/bolts act in tension to compress the four friction surfaces together .... it is the 'disc friction' that keeps the wheel from slipping on the hub: if the latter occurs, the fasteners are placed in a shear mode .... not the way they were intended.
No doubt it will work - but that was not the design basis IIRC ....

69gaugeman

Unless that paint is so uniform within a few microns (.001mm) you are going to have runout issues. The single largest issue facing rotor manufacturers is brake place to mounting face runout. They spend 100's of thousands of dollars to remove 10-20 microns of runout. It may work for a while but when one side wears of more than the other you will get pedal vibrations due to thickness variation of the brake plate. Most factory specs are .010mm maximum variation along the whole brake plate. And these are specs for your typical chebbie truck or car. The paint variation is also multiplied as it is projected to the brake surface.

I would remove the paint from the wheel face and from the mounting face. But that is just me.

Rod

hacker-pschorr

Just make sure the direction of the rotor veins matches the wheel on that corner!

Fabio421

My rotors are slotted. I thought this was stock. Is it not?

BTW the rotors look nice guys.

hacker-pschorr

Early OEM rotors are slotted on the non Brembo setups.

BC

You want the fins spinning in the direction to draw air in at the hub and push it out at the edge. Plus, real genuine disks for 82-86 are marked left and right.

AO

Not sure what you mean by fins? If you're talking about the slots on the slotted rotors, I agree. If you're talking about the vanes of the internal structure, I disagree. I remember looking this up when I got my cross-drilled rotors and it was clear that you want the vanes to expell air at the perimeter rather than at the hub. Don't remember the logic behind this, but it seems reasonable that if you're driving through rain/water you want to shed the water, not hold it.

a4sfed928

Remove the power coat on both sides of mounting face ! I have seen this several times at the track it causes your wheel lugs to appear to have loosened but in actuality the power coat softened and squashed out after the rotors heated up.

BC

Thats what I said Andrew - Fins pushing air out to the edges from the inside hub.

Chris Lockhart

I'm sure that it's probably better not to paint the actual mating surface for the wheel, but I did paint this 5 years ago when I originally painted my calipers/rotors, and I've had no ill effects from it. Just my 2 cents.

hacker-pschorr

In the second picture - the rotor "on top" goes on the front left. Air needs to be "sucked" in the center (inner) part of the rotor and "pumped" out the veins. Seams backwards until you think about it. Most people think you are trying to suck air in the veins, not so. Think of the rotor as a water pump, same theory.


BINGO!! Powder Coating is up to 400-500 degrees. On the track 900 degrees is not uncommon for rotors. This is why you should not powder coat headers, it will burn off.

AO

Sorry Brendan. At the time i read your post, it didn't read that way to me. Well at least we agree.