spoon calipers....is it worth it?

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03-08-2010, 10:50 PM

#21

y2k5S2k

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It looks like my emoticons didn't work; didn't do it right I guess.

A recommendation for good reading on brakes education:
"High Performance Brake Systems; design, selection and installation"
by: James Walker Jr.

They install some BBKits at the end of the book. Good reading, and informative.
I only paid $25 for it!

(brakes don't stop cars, tires do)

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03-09-2010, 05:44 AM

#22

ZDan

Join Date: Feb 2007

Location: Pawtucket, RI

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Quote:

Originally Posted by y2k5S2k,Mar 8 2010, 11:44 PM

[me]:I'm saying that the fluid will be cooler under the same operating conditions with the spoon calipers than with stock.

I have to chime in here, because I can't take it! The above is not true. Aluminum has a
larger coefficient of heat than steel, so the heat will "flow" into the Al. faster, but will also
flow out of the Al. caliper faster. i.e. Al. absorbs heat faster and dissipates that same heat
faster.

As you note below, heat comes into fluid and caliper primarily through the PISTONS. The PISTONS heat the fluid, the caliper body COOLS the fluid. The more efficient heat transfer through the aluminum will do a better job of keeping the fluid COOLER. In addition to this, a four-piston caliper will have greater surface contact area with the fluid, again enhancing heat transfer out of the fluid and keeping it COOLER.

Quote:

So, input the same heat into both systems, and the same amount of heat gets to the
fluid; Steel resists the input, but holds it longer. Al. absorbs faster, but dissipates it faster.
The heat will flow more evenly throughout the Al. and make its way to the fluid,

Again, the caliper body is cooling the fluid, not heating it. Which is why aluminum, with its greater ability to conduct heat, is better than steel for brake calipers. The external caliper temperature may actually be hotter with aluminum, but this is good as it further increases heat transfer to the air, whereas the less heat-conductive steel will as you observed tend to hold the heat in more, keeping the fluid hotter.

Quote:

However, this isn't the area of most concern regarding heating of the fluid; it's the
pistons. They see the heat first by direct contact with the pads and then transfer that heat
to the pistons; and the pistons are in direct contact with the fluid.
A really good way of keeping fluid cool is by insulating it from the piston/pad
heat source. Titanium spacer plates are great at doing this. Ceramic is good also, but coatin
the inside of the pistons with ceramics is kinda spendy--it's used in F1 and other race fields.

I just use the standard steel shims. Cheap, and better than nothing!