Some new construction pics from your favorite underdogs...

[Didier Beaudoin]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Denny Trimble:
Didier,
Our brake system pressures run about 1300psi under "normal operation", and all of our brake system components are rated for 3000 as far as I know.

Also, Carroll Smith advised against using the aluminum hard line. Apparently he'd seen it fatigue and fail at an inopportune time, and the weight savings aren't very much considering the added risk.

University of Washington Formula SAE ('98, '99, '03, '04)<HR></BLOCKQUOTE>

Hmm.. You got me concerned now... AFAIK, our break lines can be heat treated to stand up to 3000 psi, and the number I told about the flex hose was on the top of my head. I think it can support more than 1500 psi..

But if Caroll Smith told it wasn't recommended to use hard lines, we'd better get them off... I'll talk about it to my teammates.

Didier Beaudoin
Team Leader -
École Nationale d'Aérotechnique

[Marc Jaxa-Rozen]

Denny,

Our normal operating pressure is 750-800 psi, at least in theory (100-120 pound braking force on the pedal, which is about what Bob Woods recommended as a guideline on the old Escribe list, I believe). The aluminium lines we're using are rated up to around 1200-1500 psi in untreated form and like Didier says, heat treating might be a good idea- a panic stop would probably bring the pedal force up to 200 pounds or so and that's not a very good time to have your lines bust up.

I wouldn't be too concerned about the flex hose though, IIRC they will hold nearly 2000 psi, which is enough for a panic stop.

Thanks for the info guys-

Marc
ÉNA

[Denny Trimble]

I looked through the Smith books, and he actually does recommend aluminum or stainless hard lines in Nuts, Bolts, Fasteners, and Plumbing. "If it's good enough for the FAA, it's good enough for me", p.208.

I remember now what he remarked on our '99 car, that the brake light switch was heavy and only supported by the aluminum hard line, which could lead to vibration and fatigue. So that's an installation problem, not a general ruling out of aluminum hard lines.

Your system pressure will vary with tire size, rotor size, load transfer, piston sizes, etc, so those numbers look reasonable.

University of Washington Formula SAE ('98, '99, '03, '04)

[Marc Jaxa-Rozen]

Yep, we have largish front rotors and some serious overkill on the rear brakes, so we might not need that big of a hydraulic pressure.

Been a while since I've done the calcs but I believe that was corresponding to a 1.2G deceleration. Then again there's a massive amount of guesstimates involved, so I'm eager to see if the math holds up in real life (that won't be anytime soon though, considering the two feet of snow that just crapped down on the city)

While we're on the subject, has anyone come up with approximate μ data for common FSAE brake pads? We're using the Wilwood Polymatrix D compound and I wonder how it compares to the values mentioned in Tune to Win.

Marc