New rotor question
 

I'm in the process of updating my rotors and brakes on all 4 wheels of my 2015 c300. There is quite a difference in weight between the stock Mercedes rotors and any off brand rotors. I've seen differences if 20 pounds per wheel. Will the additional unsprung weight cause any major problems or should I stick with original parts. Any help greatly appreciated. Thanks

less weight means more noise. look at zimmerman rotors. use them all the time and never had issues.

Many like to reduce unsprung weight; but, rotors that are that much lighter would raise quality concerns in my mind. On a daily driver that is only five years old I'd use OE or OEM rotors and pads

Do you need rotors, can yours be resurfaced?

Just my $0.02!

Good luck!!!

I would think that lighter rotors would tend to warp easier.

Agree with could warp easier...not a desirable issue on a daily driver.

20# per wheel more than the stock rotors? Seems impossible. I'd check that fact. I'd never put an extra 10# onto my unsprung weight per wheel. It will make it ride like a truck and hurt handling. I can feel a difference of 4# per wheel.

You aren't seeing 20# differences per rotor. The mass of the rotors won't be dramatically different from manufacturer to manufacturer, because the dimensions are standard, and the density of iron alloys doesn't vary much. So stop exaggerating whatever problem you're seeing.

Unspring mass is really beside the point. The thermal mass of the braking system is as important to braking as any other characteristic. If you have a rotor with lower mass, it will have less capacity to absorb heat and will fade more quickly. Lightening your brake rotor is generally a bad idea.

you accusing me of exaggerating?

Not at all, the OP says his rotors are 20lbs heavier, that's what I was referring to. Two rotors of stock design are going to be very close in mass.

yes.

ATE coated with Akebono pads. Done.

Don't do OE pads, they dust like mad and are annoying. OE rotors are fine. Whatever you get, make sure they are coated otherwise hats and vents will rust.

I would be surprised if one rotor was a pound heavier than another, unless you are talking about carbon fiber rotors vs iron.

As already stated. I've been running Zimmerman rotors for years with no issues.

I’ve ran the rock.Auto bottom of the bucket cheapies for years with no problems.

check out cquence dot net

The weight of a MB rotor is 11 pounds. Compare that to a powerstop or stoptech rotor.

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Cquence.net does not list rotors for my car.

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Here's what I found.

Zimmerman - 21.4 pounds

Stoptech - 22.0

Powerstop - 18.74

Brembo - 11.3

Mercedes - 11.0

So I'll go with Brembo. Mercedes tuned my suspension for light unsprung weight so I'll stay with the recommended guidelines.

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Where exactly are you obtaining those listed weights? Shipping information from online vendors? If so, you'd be remiss to rely upon that as accurately reflecting the true weight of each rotor. You're barking up a tree where there's no squirrel.

Applying a little bit of analytical thinking would be helpful. You'll note that the examples you posted reflect a difference roughly equal to a doubling of weight for certain examples versus others. So... what are you seeing? A single rotor weight versus a shipping unit of two rotors?

The outlier is the powerstop brand, which is likely: A.) an inaccurate listing, B.) showing the net weight vs. gross shipping weight (although a cardboard box doesn't weigh much), C.) they are lower in mass due to being skimpy (unsafe) garbage - where they use larger cooling vents to save on material costs while maintaining correct external dimensions, or D.) they are lower in mass than the others because they are exotic two-piece rotors, i.e., aluminum hats with steel friction surfaces.

This, there's no way there's 10 lbs of difference between the heaviest and lightest. Assuming the same outer dimensions (because the rotor has to fit into the same caliper, and the hat has to be the same thickness), to add 10 lbs a foundry would have to add material to the inside of the rotor, eliminating the vents.

I agree with the two previous posts. Most likely it is a one vs two rotor weight.

I use to cut bearing races up to 26 inch diameter on a cnc lathe. We used nickle,chromium steel, then heat treated and quenched. Bearing races then ground to final spec. We had some a year old grow up to 60 thousants. So we started after quench a nitrogen bath,to stablize metal. I have alway wanted cryro treated rotors. You should be able to get them hot,and go thru rain,with no warping.