Ceramic vs semi metallic brake pads

[Joseph E.]

I recently installed new ceramic brake pads on my 1965 convertible and have noticed a difference from the semi metallic pads that came out. The car doesn't seem to stop as well with the ceramic pads and the brake pedal feels different than it did before the ceramic pads were installed. The reason I switched from the semi metallic pads to the ceramic ones was to get rid of the squeal from the brakes when the pads were cold. I accomplished that but I'm not too happy with the difference in feel and grab with the ceramic pads. Is this characteristic of the ceramic type of brake pads? I've always used Bendix semi metallic pads and have kept with the same name brand just in a ceramic version. Any input would be most appreciated. Thank you. Joe

[Duke W.]

Re: Ceramic vs semi metallic brake pads

You probably don't have power brakes.

The fiction coefficient range should be stamped on the side of the friction material. Two letters indicate the Cf range at 250 and 600F material face temperatures. You want it to be at least FF (0.35-0.45, which is a pretty broad range) with power brakes and probably GG (.045-.055) is best for non-power due to the higher Cf, although GG isn't common.

Ceramic pads are quiet, clean, and long lasting, but they don't have a high Cf.

Especially if you don't have power brakes pay attention to Cf. Chevrolet designed the manual brake system to require 120 pounds of pedal effort for a 1g stop with the production pads that were probably the equivalent of FF. (The standard was not in place back then.) I suppose that was considered acceptable in 1965, but it's about three times what a modern car requires.

Duke

[John H.]

Re: Ceramic vs semi metallic brake pads

I recently installed new ceramic brake pads on my 1965 convertible and have noticed a difference from the semi metallic pads that came out. The car doesn't seem to stop as well with the ceramic pads and the brake pedal feels different than it did before the ceramic pads were installed. The reason I switched from the semi metallic pads to the ceramic ones was to get rid of the squeal from the brakes when the pads were cold. I accomplished that but I'm not too happy with the difference in feel and grab with the ceramic pads. Is this characteristic of the ceramic type of brake pads? I've always used Bendix semi metallic pads and have kept with the same name brand just in a ceramic version. Any input would be most appreciated. Thank you. Joe

Joe -

The original factory pads were an organic friction material, required only moderate manual pedal pressure, and rotors would last 100,000+ miles with no problem. The next "upgrade" (?) pad material was semi-metallic, which is more expensive, required higher pedal pressure, cut expected rotor life just about in half, and squealed. The most recent "upgrade" (?) pad material is ceramic, which the Marketing guys love, is even more expensive than any of the semi-metallics, has a lower coefficient of friction, requires MUCH higher pedal pressure to generate ordinary braking forces, and they squeal.

Begs the question of why "upgrade" at all? The OEM organic pads require virtually no maintenance, don't wear the rotor friction surfaces, require only normal pedal pressure, and don't squeal. Unless you're going to competitively road-race the car, why put road-race brakes on it and have to live with the downsides in everyday driving?

[Duke W.]

Re: Ceramic vs semi metallic brake pads

I believe Bendix offers a line of brake pads that are engineered to have OE performance characteristics for all cars, including vintage cars. They obviously are asbestos-free, but the friction material is as close to OE performance as current technology allows. These (or OE pads if you can find a set) are the best choice for replacement pads on cars used for normal road driving.

There are a zillion different brake materials on the market, and if you deviate from OE or OE equivalent you are taking a chance as the performance characteristics may be disappointing, so be wary of "upgrading" pads when it comes time to replace.

I'm always amazed how many "upgrades" (engine, cooling system, suspension, steering, brakes... you name it) turn out to be disappointing to the owner if not an outright disaster. These cars were very well engineered, and if you don't have an engineering level understanding of the system you are dealing with, your "upgrade" can easily become a downgrade.

Duke

[Steven B.]

Re: Ceramic vs semi metallic brake pads

Joe, John and Duke have given good advice. I worked in the brake and clutch friction lining industry earlier in my career and we experimented with hundreds of compounds, most did not work as you can expect. To become an OE friction product it had to perform better than the other compounds and generally had much more engineering and test time (and $$$). Our testing was pretty brutal in the lab and on the cars and trucks. We also did comparison testing of aftermarket materials. Shear testing, the friction material separating and/or leaving the backing plate, was higher with the non-OE materials, OE was quieter and had better cold response, generally. I also dabbled with a couple of competition Corvettes, an A/P L-88 SCCA car and a small block SCCA and NCCC car. This is not to say there are not some very good aftermarket linings, it is just much easier to get acceptable street performance without researching the heck out of the pad, your car, and your driving requirements by installing OE. From my experience unless you are competing with the car use the OE formula pads. Steve

[Mike E.]

Re: Ceramic vs semi metallic brake pads

I stuck with good ole ACDelco 17D8 organic pads. Unless your racing I don't think you need anything else. Buy two sets and you can just eek out free shipping. The funny thing is most internet vendor think there should be a difference between front and rear pads.


Mike