Preparing used brake rotors for new pads

[Chris142]

I was shown at about 14 to rough up old rotors with a rol- lock sanding disc. Always worked well for me.

I see others just put new pads on the old shiny rotors.

Thoughts?

 

[Tdog02]

I've done a few "pad slaps" in my time. When the rotors are in good shape with no grooves or gouges. I have only used sanding disc's a couple of times. They were quieter when I did that and no squealing.

Now days it is just about cheap enough to replace the rotors if I'm doing it myself.

 

[BigCahuna]

I usually just spray the old rotor with brake cleaner, give it a few scrubs with emery paper, then throw the pads on. If your rotors are warped, nothing besides resurfacing will help.,,,

 

[Ed_Flecko]

Do your pads have enough material remaining to have them resurfaced?

Ed

 

[AdmiralYoda]

If the rotors are in good shape.... I do nothing. Many of the pads have a break-in coating to help bed the pads anyways. If the rotors look suspect...change them out.

 

[D1dad]

If my car has open wheels, which mine all do. I can’t stomach looking at salt licked rotors any longer than a few years. My 03 Altima was the last car I owned that weren’t open wheeled and did a few pad slaps which amounted to doing nothing to the rotors. Never an issue.

 

[shortyb]

I was shown at about 14 to rough up old rotors with a rol- lock sanding disc. Always worked well for me.

I see others just put new pads on the old shiny rotors.

Thoughts?

Roloc maroon discs for years. Strips any old transfer material/glaze like magic and cleans/conditions the surface for new pads. Never slap without them.

 

[The Critic]

Never slap without them.

I have never seen a factory service manual specify the procedure you're describing. Smoother is generally better for pads, most ceramic pads have minimal ability to cut thru a rough surface finish.

 

[ClutchDisc]

New rotors every time for me. I will not reuse old rotors with new pads.

 

[D60]

Roloc maroon discs for years. Strips any old transfer material/glaze like magic and cleans/conditions the surface for new pads. Never slap without them.

Agreed although I'd use the Velcro backer on a 4.5" angle grinder.

 

[JavierH19]

Mostly pointless since the pads will polish the roughed up surface. The lip is rarely an issue but a die grinder with a flat sanding pad or the carbide bit if I already have one set up on a holder to quick swap on the lathe takes the lip off but i don't bother doing that to a 1-2mm lip anymore.

 

[shortyb]

I have never seen a factory service manual specify the procedure you're describing. Smoother is generally better for pads, most ceramic pads have minimal ability to cut thru a rough surface finish.

Most won't, easier to sell new rotors. Smoother IS better and is exactly what the Rolos provide. Without the shiny glaze or excess pad material. Just nice clean surface for new pads to get all intimate with

 

[shortyb]

Agreed although I'd use the Velcro backer on a 4.5" angle grinder. View attachment 346616

Thats almost exactly what mine looks like too.

 

[nthach]

I’ve seen a GM or BMW service bulletin that recommends not refinishing a rotor if all is being done are new pads. Unless of course, it’s scored deep. Finding someone who can cut a rotor without introducing more play/slop is hard these days.

Unless it’s a truck, European car or something with “performance” brakes, organic brake friction really doesn’t wear down rotors and they need to transfer a thin layer of material onto the rotors for cohesive friction. Semi-met/low-metallic pads will wear down the rotor as time goes on. I’ve pad slapped two cars without issue lately.

 

[Elkins45]

Slap ‘em on and go is my philosophy. It’s worked for me for decades now.

 

[iCurious]

I never do pad slaps. Always pads and rotors or don't do it.

 

[Bottom_Feeder]

Brake rotors are replaceable wear items. To me, using new pads with old/used rotors is like putting on the same pair of underwear after you get out of the shower.

 

[bdc101]

I usually just spray the old rotor with brake cleaner, give it a few scrubs with emery paper, then throw the pads on. If your rotors are warped, nothing besides resurfacing will help.,,,

Resurfacing won't un-warp warped rotors... been there, tried that...

 

[barryh]

I replace rotors when they reach the minimum stated thickness and they'll go though several sets of pads before that happens. I see no reason to replace them prematurely just because.

 

[The Critic]

Resurfacing won't un-warp warped rotors... been there, tried that...

Properly resurfacing rotors will correct DTV and lateral runout issues. Every time.