Good morning, TaycoTrains;
Oh, boy. That question is one that actually has many answers, and the better one will merely be the one that fits your operating conditions in most of the ways it can.
There are many friction materials used in our brake pads; organic, metallic, semi-metallic, sintered metallic, ceramic, and a couple of others. Each type has advantages, and some disadvantages.
The original soft organic pads normally will have the highest friction rating, but they also wear out fairly rapidly requiring more frequent replacement. They also may not have a very good high temperature characteristic, and they may fade on you when going down a long hill. Usually they do have the feature of a lighter touch on the brake pedal for the resulting braking effect.
The metallic pads are much better for high speeds and heavy braking where they dissipate the heat more quickly. This is one reason why racing vehicles often will use them; they may have lower friction but they are consistent over the time period of the race; they have very good "fade" resistance. They do wear the disks or rotors more quickly, and they usually do require a heavier force on the brake pedal.
The semi-metallic pads are more of a combination of the organic material with a higher percentage of metallic particles in the organic material to help move the heat away from the pad-to-rotor interface and dissipate it. Aluminum, copper, and brass are fairly common metals used in these. They have friction ratings more like the organic pads, and they are less wearing on the rotors. For my uses, these are the pads that I prefer, but, again, that is only my preference. I do like the ones made in England by the largest friction material maker in the world.
The sintered metallic pads are another variant on the combination organic-metallic particle friction material mixture, but the metal particles are heat treated to harden them and make them more wear resistant. This also means that they are harder on the rotors and they do wear the rotors more rapidly. They do have good high temperature characteristics and they will also provide more consistent braking at high temperatures, much like the standard semi-metallic pads, but with the disadvantage of more rapid rotor wear.
The ceramic pads have very good high temperature characteristics, but the friction rating is a little lower again. Often they are used in performance and race vehicles. They can also be harder on the rotor wear. I did hear of one report of a problem with a ceramic pad that developed a problem while it was hot from braking and was splashed with water, but I have not been able to confirm this rumor nor get any additional details of the conditions under which this was supposed to have happened, so I am not sure how much credence to give this one report.
All I can really recommend is going to a good brake shop and talking with some of the older guys there about the different brake material characteristics, and see what recommendation they might offer for your vehicle and the braking conditions that it might see in the way that you drive your vehicle. Driving in the mountains is different from driving on the plains when looking at the way that the brakes are used.
For my vehicles, again, I normally use the semi-metallic pads, and I check the pad thickness with a bright flashlight and an inspection mirror to see how the pads are wearing. If you see an angular wear or a varying thickness of the pad material across the pad, there might be a problem with a stuck pad, rust, dirt or mud, or a misalignment of the caliper. The pads should move back and forth in their mounting in the caliper, and the caliper should be able to move on its mount to allow it to center itself over the disk while braking. The main thing is to change the pads before the friction material is worn away and the metal plate part of the pad begins to rub on the rotor surface. That problem will really decrease the time period between rotor replacement. Inspect the pads, or have them inspected, at a regular interval, and at least annually.
Brake fluid is another controversial subject. Today, most people seem to be quite happy with the standard DOT-3 or DOT-4 brake fluid, but I still have a preference for the DOT-5 silicone base brake fluid, but it is not easy to find now, and the brake system should be flushed when changing to DOT-5. You might need to carry your own supply of DOT-5 for topping off the brake fluid reservoir if required. I have heard of some people saying that the DOT-5 brake fluid should not be used with Anti-Lock Braking Systems (ABS), but I cannot see myself why this should be. Others may know of why this might possibly be so, but I do not, nor do I have an ABS system on my 1987 vintage motor home. And I really do like the accepted fact that the DOT-5 silicone base brake fluid is not hygroscopic; it does not absorb moisture or water out of the air, as the DOT-3 and DOT-4 glycol base brake fluids will do. This can be important with a vehicle that will sit for much of the year, and any moisture in the brake fluid may settle out and cause rusting and degradation to the inside of the brake lines, calipers, and other parts. Yes, I do have a history of using DOT-5 brake fluid over a multiple year time period with no problems detected yet, other than the higher cost and the additional work when changing to the DOT-5.
Enjoy;
Ralph
Latté Land, Washington
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