Re: Silicone brake fluid

[Trisha Bethen <trishab@mv.mv.com>]

On Sat, 10 Aug 1996, Richard Klein wrote:

> On  8 Aug 96 at 11:41, Gary G. Erickson wrote:
> 
> > I guess I should clarify my statement.  I ment that it was one of those
> > two object (air _or_ water) than DOT 5 didn't like to play with.  I have
> > been corrected, that I should have stuck with the statement about DOT
> > 3/4 being incompatible with DOT 5 and left it at that! <grin>
> > 
> > BTW, since we're on the subject of brakes, is anybody familiar with the
> > Hawk brake pads?  The guy at my local race shop just loves them.  I've
> > ordered a set to try.  (it's _only_ $50  ;-]  )  They sounded good at
> > least for aggressive street use and mild track.  Coefficent/Friction of
> > .44, no-fade operating range of 100- ~1100 degrees F.  Supposed to be
> > extremely rotor-friendly.  We'll see about the dust however!
> 
> Rider magazine had an interesting, if not terribly in-depth, article 
> on brake pads in the latest issue.  It's about motorcycle brake pads, 
> but most of the info is probably applicable to auto applications.  
> Correct me if I'm wrong...
> 
> Paraphrased from the article:
> 
> Brake pads fall into 3 general types:  organic, semi-metallic, and 
> sintered metal.
> 
> Typically, organic pads are at the lower end of braking performance, 
> wear faster than semi-metallic or sintered metal pads, and are easy 
> on brake rotors.
> 
> Semi-metallics are similar to organic pads but are impregnated with 
> bits of metal such as copper or brass.  They tend to provide more 
> friction and longer wear than organics, and can be harder on rotors.  
> Semi-metallics with the metal distributed more evenly throughout the 
> pad should be easier on rotors than pads with the metal present in 
> relatively large lumps.
> 
> Sintered metal pads work better than the others when cold, are quiet, 
> and give good braking power over a wide temperature range.  They are 
> somewhat porous, which can help break up a thin layer of water, 
> giving better braking performance in the wet.  They have a reputation 
> for being hard on rotors, but lubricants can be added (in the 
> manufacturing process) to lessen the impact.
> 
> I thought they mentioned which type of pad creates the most dust, but 
> I can't find it now...
> 
> They also point out that a pad that's great on the track may not be 
> the best choice on the street.  Racing pads are usually designed to 
> create the most friction at high temperatures - temperatures that the 
> brakes may never see in street use.  Street oriented pads are 
> designed to create adequate friction at lower temperatures.
> 
> I've read in several magazines (though not in the fore-mentioned 
> article) that DOT 5 brake fluid is extremely hard to bleed all the 
> air out of, thus most motorcycle journalists won't use it.  It is 
> used in show cars, though, because it doesn't attack paint like DOT 3 
> & 4 fluids do.  There is also a DOT 5.1 fluid (though I never see it 
> in stores) that is compatible with DOT 3 & 4 fluids, ie not 
> silicone-based.  It's distinguishing feature is that it can handle 
> higher temperatures than DOT 3 or 4 specs require.
> 
> A little knowledge may be a dangerous thing, but I'm happy to share 
> what I've got... :)
> 
> Corrections and clarifications are invited.
> 
>    -Rich
> 
>    '85 Audi 5000s   '72 Suzuki GT380
>    '85 El Camino SS '73 Suzuki GT550 in pieces
> 
>     in beautiful Bay City, Michigan
> 
Some of the racers in the American Sedans of SCCA are using Hawk brakes 
and like them.....so....?????/As for organic brakes.....back a few years 
ago....Ferodo was very successful in building brake pads for endurance 
racing that were organic with no metal.....not sure whatever happened to 
them....I'll try to do some research.