resurfaced or new rotors

[dru]

i just got my brakes serviced at a local shop. they told me that my rotors were to run down to resurface them and that i needed new rotors. they had about an 1/8 inch protrusion around the perimeter. i got it back home looked at the rotors and they had a swirly sanded look to them, lines running from the center to the perimeter of the rotor. do new rotors have this look to them? i thought they would have a smooth finish to them. im wondering if they actually replaced the rotors or just resurfaced them.

thanks

 

[Mark_88]

My suggestion is to always ask for the old parts back...that way you know you've gotten at least different parts put in...and if you're not sure, measure the thickness of the rotor, then go to a parts store and ask to see a set of rotors for your truck...and measure them...

But a new rotor would be shiny all over...and would "look" new...pull the tire and see if the hubs are shiny...and check the area where they fit over the spline to see if it's rusted...if it is...they've resurfaced your rotors...and if they charged you for new...then you can take it up with them...

But even new rotors do have swirls from machining...unless they are cast...which they shouldn't be...IIRC, that is...

Did you have the bearings done at the same time by any chance?

 

[dru]

i just measured them without taking the wheels off. they are just shy of an inch 15/16" ill look up the width of a new rotor.

thanks

 

[MagnaV30]

they have the "swirly" look to them simply because it aids in bedding in the new pads etc.
Much the same as when you hone cylinder bores when installing new pistons, or at least new rings.

 

[cocoasranger]

If the old ones had an 1/8" ridge on the edge they were almost certainly shot. The minimum thickness the rotor can be turned down to is stamped on the rotor near the hub. Many new rotors come with a swirl pattern to seat the pads and eliminate complaints due to squealing.

The difference in thickness between a new rotor and one too thin to save is often only about .125 of an inch (1/8")

 

[Evan]

unless they are cast...which they shouldn't be...IIRC, that is...

They are cast aren't they? I thought they were lost-foam cast, and then put on a lathe for fine tuning.

 

[cocoasranger]

Yes, cast iron, usually ductile cast iron. You can see the casting lines and cast in numbers if you look close. They are then machined and sometimes given a swirl finish to the swept pad area like they do on a rebored engine cylinder to ensure proper pad seating.

 

[Mark_88]

That's two things I learned today...lol