brake pad pins - why not stainless?
 

Just a general question - anyone know why they don't make the brake pad retaining pins out of stainless steel? Seems like it would last much much longer if stainless, as there is always corrosion on the ones you remove.

Paul

Because stainless is a HARD steel and would chew through the relatively soft pad backing and caliper mountings like butter. Not a good thing. Think of all the vibrations the pads are transmitting and imagine a file going at that speed.

Why don't they make the exhaust out of stainless too? - Cost..if you have to buy a set of pins every time you buy pad's....ker-ching! profits are up!
As with exhausts, you can get aftermarket stainless pins, for bikes I know, so most likely cars too!
cheers!

Actually they do. Eberspaecher

I think the Benz is the first car I have owned that did not come factory with stainless exhaust. Pity :(

You can't make a blanket statement that stainless is a "hard steel". There are different grades of stainless steels, just as there are different grades of plain carbon and alloy steels. Your analogy is wrong. If any blanket statement can be made, it's that stainless steel has a higher tendency to gall than plain carbon steel, and it's considerably more expensive.

I think stainless has less of a tendancy to gall that rusted steel.
There are grades of stainless that would perform well and machine easily enough, so it must be cost or tradition.
Some brake parts on Japanese cars have been made of stainless/corrosion resistant steel since the '70s. Same with exhaust hardware.

Hah! I can make any blanket statement I wish 'cause this is the internet!:P So there!

The pad backing and the calipers are made of a low carbon steel for heat transfer and vibration resistant purposes. The lowest grade of stainless is, I guarantee you, harder than either of the two other parts.

Calipers are cast iron, not steel. Pots and pans grade of stainless is quite soft, to the point of being gummy. A good alloy of stainless for brake pins would be 304, which is not harder than medium carbon steel.

Sigh, I give up, you guys win. So YOU tell the guy why they don't make the pins out of stainless and don't give me that "cost" line because it ain't true. The minuscule difference in cost wouldn't even faze those guys at Daimler 'cause it'd be included in the base car expense.

I don't really know why they aren't SS. All sorts of stuff is made from SS including cheap pots and pans. It could be cost, car makers will cut cost to the penny.

That's not true, cost is always a concern. No one can say for sure in this case without asking the design engineers, but usually they give the vendor a spec to fulfill, like corrosion resistance against 500 hours of salt spray. If coated steel does the trick, and there are no other field issues, then why go more expensive?

Thanks all - yes the blanket statement of stainless being "hard" is plain wrong, if you want a quick description of some of the more commonly available alloys - their strengths, machineabillity etc look at speedy metals (they sell in small quantities). Hit a brake pad backing or a brake pin with a file and you will score both of them.

I asked because I have the equipment to make my own and was wondering if there was an actual reason that I may not be aware of. I figure I'll make some to try out. Now to get a new one so I can get an accurate measurement (99% that the OD is a even metric size) 303 stainless machines really easily (no work hardening problems and is resistant to galling).

Paul

You need to look at more than just machinability. 303 is subject to increased corrosion in warm salt environments, something that will occur on a brake caliper in MA. http://www.azom.com/article.aspx?ArticleID=2866

Feel free to experiment, but your OEM pins served you well for a decade or so.

I will give you the cost line because it is a big factor in deciding which materials are used in an application. I know, because I am intimately involved in these decisions.

Why limit your discission to pins? Why not make all parts on a car out of stainless steel? I mentioned cost. But theere can be other factors as well. If you look at stainless in the galvanic series, you's find it would cause the adjacent touching steel components to rust quicker, and even more so if it contacted aluminum. Then there's the issue of sensitization of parts that are either welded or processed incorrectly.

That's why you have pins that are steel that is hopefully zinc or Dacromet coated.