So last night I was researching some brake stuff and one of the interesting things I ran across is these things:
http://www.fourproducts.com/FSBC.htm
A brake pad shim with a heatsink that sticks out above the caliper to aid heat dissipation.
Unfortunately they only make it for a few different models, and I see three potential improvements they don't have - a ridged surface facing the caliper to decrease heat transfer (I also learned that racing calipers often have a ridged surface on the piston face for the same purpose), an insulating coating on the caliper-facing side, again to keep heat away from the hydraulics where it causes the big problems, and finally the heatsink design isn't that great, there's a lot of room for improvement.
These would be pretty easy to fab up yourself with some aluminum sheeting of the right hardness (to not get smooshed the first time you hit the brakes hard), some computer heatsinks (which are often well-designed off the shelf) and the right kind of thermally-conductive bonding agent (or maybe some kind of welding/soldering?)
All the brake talk in the VW challenge car thread got me thinking that bigger brakes carry a long list of disadvantages, with often the only advantage being "they don't fade so easily" so any means of doing that without going to bigger brakes could be very helpful.
Race pads and fluid alone have taken care of me on most modern cars. We did burn the piston boots off the Civic at Lemons, but the calipers were still working fine. I rebuild them between crapcan enduros anyway.
The only issue I see with those heat spreaders is that you need a large rim to clear them. Maybe they could be bent horizontal.
Yeah they could be bent horizontal, almost any shape is possible once it fits in the rim and can be installed in the caliper.
I sketched up a concept here:
This is the side facing the caliper you're looking at. The gray part is a cut aluminum plate. The yellow part is a heatsink stuck on. It's very easy to ruin the thermal conductive properties of a metal plate and that's what I've done on the caliper-facing side of the shim. The red stuff represents caliper paint (ceramic would be better but pricey) and the black lines represent a quilted pattern created on it by cutting lots of little shallow grooves.
Look at the bottleneck. You can have all the fin you want, but if the heat has to get through a small thin area between the fins and the piston/pad, heat transfer to the fins will be minimal.
Well those commercially available ones I linked to seem to work quite nicely with the same limitation - in fact theirs are worse because they have cutouts in the metal between the pad and heatsink.
Instead of simple heatsinks, use heat pipes:
http://en.wikipedia.org/wiki/Heat_pipe
Transfers 50-100 times more heat than solid Aluminum, no moving parts.
Relies on the heat of vaporization, instead of conductivity.
The ability to mount the 'cold' end (aka radiator) remotely from the 'hot' end (aka brake caliper) gives a lot of flexilbility to take advantage of airflow.
These are commonly used in laptops to remove the heat from CPU's.
Carter
I actually thought about heatpipes but remember the shim has to be thin, 2mm would be pushing it.
GameboyRMH wrote:
I actually thought about heatpipes but remember the shim has to be thin, 2mm would be pushing it.
heat pipes would work better attached to the caliper than on the pad
Neat ideas to engineer around compromised engineering.
Didn't John Fitch develop a water cooled braking system some time ago?
Might be something to research.
Trans_Maro wrote:
Didn't John Fitch develop a water cooled braking system some time ago?
Might be something to research.
http://www.gtrblog.com/2009/12/13/willall-racing-wr35ws-brake-coolin/
I know shimano has been doing it with their MTB disc line for a bit now
GameboyRMH wrote:
Well those commercially available ones I linked to seem to work quite nicely with the same limitation - in fact theirs are worse because they have cutouts in the metal between the pad and heatsink.
Operative word, "seem". Not saying some cooling can't be achieved. Massive cooling cannot.
Just because something is made and marketed doesn't mean it works as advertised. Be it turbo flow tailpipe extensions, tornado intake air filters, or rattle shim mounted cooling fins. Physics keeps getting in the way.
foxtrapper wrote:
GameboyRMH wrote:
Well those commercially available ones I linked to seem to work quite nicely with the same limitation - in fact theirs are worse because they have cutouts in the metal between the pad and heatsink.
Operative word, "seem". Not saying some cooling can't be achieved. Massive cooling cannot.
Just because something is made and marketed doesn't mean it works as advertised. Be it turbo flow tailpipe extensions, tornado intake air filters, or rattle shim mounted cooling fins. Physics keeps getting in the way.
Well I was looking at the graph at the bottom of the page and assuming they didn't fudge it.
I believe that water cooled calipers are old news in the roundy-round world.
erohslc wrote:
I believe that water cooled calipers are old news in the roundy-round world.
There was also a set up that circulated the brake fluid through, using essentially some one way valves and return tubing to the reservour. I guess it didn't work very well after all, since I haven't seen it in years.
Isn't there a little issue with fitment between the wheel and the caliper? Those would never fit on my car.
Alright new 2-piece concept here to ease installation, allow for a bigger heatsink area and reduce the required caliper-to-wheel clearance.
The idea is that the tab on the shim sticks up above the caliper, and then when the whole caliper is reassembled with the shims and pads in place, you push the two hex-head bolts into place (heads seen here) and put a nut on the other side to hold the heatsink on, ideally with some kind of thermal grease in between the heatsink and shim (contact surfaces would be polished). Yes the shims would need to have special holes to hold the bolts and the tab on the heatsink would be "countersunk" to accept both. Remember you can't get a screwdriver back there once it's together. In fact the bolts would have to be as short as possible to keep it from being a bitch to install.
