What determines a in expensive rotor to a expensive one?

 

Moved here

 

Depends on your perspective. An expensive one can be inexpensive to purchase but if incorrect for the application and/or poorly manufactured, will cost you a lot more in the end.

C3 rotors are incredibly durable. If they have a rusty appearance, you can soak them in CLR and wire brush them to look like new.

Why do you think you need to replace them?

Keep in mind, the fronts are different from the rears.

 

gooves in the surface and scratches what is the best material on the market

 

g.m. rotors were 1.250 from the factory,you can cut them to 1.230. The originals are the best.Try getting them first before replacing them.

 

Try getting them turned first before buying new ones.

 

Agree try to save old ones as everyone is sayng.

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I have been using rotors from ROCKAUTO and they have been great. I prefer the rotors with the slots and holes drilled in them to keep the gas from getting in between the rotor and the pad. The slotted units also have a good habit of cooling down faster from hard usage.

I have another GM product DD that came with TOO small a rotor on the front of the car. The result is a regular warping of the rotor and then they need to be replaced every 13-15 thousand miles. I finally got to the point where I sent a set of them to a company who did the Cryogenic Thermal treating to the rotors. This makes the rotors substantially harder than the original material. My DD has gone three close to four times as far on a cryogenically treated rotor.

The cost of getting the rotors treated has probably gone up like everything (thanks, Joe) and I am not sure what it costs today. On many cars it is probably not worth treating the rotors unless you have an issue like my DD does. If you are going to drag race the car you might get away with a stock rotor, if you are road racing then you will want the harder more durable rotor on your Car.

To me a plain rotor is just a factory replacement with nothing fancy. The inexpensive rotor is a "base" replacement part. Today they offer things like performance coatings and the really expensive rotors are going to be slotted and drilled. When using the drilled and slotted rotors you might want to do a check every so often to ensure that no cracks form near the holes in the rotor. This is a fairly common failure mode for the higher end rotors.

It all depends what you are doing with your C3 as to which rotor is best in your application. For many years I have been using the rotors I have and they have sustained over ~forty 1/4 miles runs and several 0-100 runs and the standard rotors were just fine. On my C4 where you can actually see the rotor though the wheel is where the slotted/drilled rotors really look nice in my humble opinion.

In my quest for good maintenance I have been taking my Infra-red thermometer with me and measuring the rotor temperatures. I check the rotors to be sure that they are all running a similar temperature and are not overheating. This will tell you if you have a caliper that is not letting loose completely or other issues.

I love watching the race cars with Carbon rotors while in the middle of a race. They get those rotors glowing bright Red while diving into turns throughout the race track.

 

Thanks

 

Do you have a way of measuring rotor runout, and understand the importance of doing so?

The number one reason NOT to swap rotors is that by introducing runout, you can pump the brake fluid out of your calipers (and air into them). This is especially bad with lip-seal calipers.

My go-to thread on this has been deleted by the author, but here's a video that explains the process. It can be a bigger can of worms than the calipers and master cylinder.

 

To answer his question in the first post.......a premium rotor is made from longer lasting, higher quality iron. It will generally also have the least amount of runout.

The best is to have an OEM rotor turned on the car. There aren't many places that offer this service anymore and it is fairly expensive. Once you remove a rotor and have it turned on a lathe....all bets are off as to the rotor runout once installed. It would be best to first measure the thickness of the current rotor to see if it even can be machined. If your primary concern is to enjoy the car long term and not to be servicing it more often and your current unknown rotors are near the end of their life I'd recommend replacing them with a premium replacement rotor like Wagner or Brembo. You definitely want to measure the runout once installed though. You can buy a cheap magnet base and dial indicator from places like Harbour Freight or Princess Auto (here in Canada).

Everyone seems to be telling you to save the old ones but do you know the history of them? Have you just recently purchased the car or have you had it for many years? The current ones on the car may have bad/poor runout to start with and perhaps beyond minimum width. If the current rotors are too rusty ....most shops will refuse to turn them.

 

Inexpensive one is made of cheap-*** steel from China (probably). When it comes to proper and SAFE operating of the vehicle, saving a few $$ on part cost makes NO CENTS to me.

 

I agree that cryo treated rotors are much harder.

But I have to ask if you track your car. I have not gassed a set of brake pads for some time. The new materials that they use are substantially better than they used to be.