Attemtping to build an electrathon car with my fellow classmates. I am responsible for the brakes and am having trouble deciding what type would be best to stop a 300-400 lb car going 40 mph. I believe disk would be best but if anyone happens to know something that would be better or even a good web site to buy brakes please help!!

Try old motorcycle parts.

Why do you need to stop ?

old motorcycle parts is the best, most bikes weigh at least 300lbs. You can get old mechanical hydraulic systems off of any old bike. With steel braided lines, and 6-piston calipers on a double front disc, I could slow to 90 from 160 in just couple seconds using 2 fingers.

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Smart

If you need to keep things really light (although the car seems heavy), then you should look to bicycle disc brakes. The issue with creation of the mounting studs will be interesting, as will the method by which you attach the rotors to the wheels you use. If you use bicycle wheels, already, just use disc-hubs and then look at getting some 8" rotor, hydraulic brakes, such as those made by Hope, Hayes, Magura or Avid.

Thank you all for the helpful advice.

How quickly do you need to stop. Tandem cyclists (same weight/speed) can make do with two caliper/cantelever/V brakes + an Arai drum brake.

The electrathon car need to come to a straight stop from a speed of 25 mph in less then 40 feet. Also if anyone knows any websites that i could buy brakes or even brake/wheel assembly please help.

I believe your best bet would be an anchor, connected to a really strong chain......