Most US made FF rotors are .250' thick, and many people have thinned theirs down to .187 at times. I've seen even thinner on a couple of cars used at tracks that don't tax the brakes all that much.
A lot will depend on the rotor material (which type of cast iron it is) and the pad compound being used.
Most US made FF rotors are .250' thick, and many people have thinned theirs down to .187 at times. I've seen even thinner on a couple of cars used at tracks that don't tax the brakes all that much.
A lot will depend on the rotor material (which type of cast iron it is) and the pad compound being used.
Actually, it looks like the standard thickness is 7.0mm or 0,275.
Your icp ld20 replacements for the 0.250 rotors are a great optization for light cars, but designing them for 7.0mm thickness rotors would alleviate some alignment challenges.
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'Stay Hungry'
JK 1964-1996 #25
Cracking tendencies depends to a major degree on the type of cast iron used. Gray CI is the most prone to thermal stresses because of the sharp-edged nature of its graphite flakes. "Ductile" or 'nodular"CI is much less prone to thermal stress cracking because its graphite is shaped more like lumpy raisins - it doesn't have the sharp edges that gray CI has. Compacted Graphite Iron is even better, since its graphite is more of a "ball of worms' structure, but so far is not commonly used because of its extra expense and the fact that there are not that many foundries that pour it, at least on a regular basis.
Believe it or not, many/most of the vented rotors you see are still being done in gray CI, partially because of it's ability to flow through thin sections in the mold much more easily than ductile. The highest level vented rotors are being done in CGI, but will cost a lot extra.
What can actually be used as the minimum thickness will ultimately be determined by a combination of the thermal stresses and the mechanical stresses, with both, of course, being partially governed by the maximum rotor temperature. Most FF's with 1/4' rotors are actually under-stressed to a large degree - great for longevity, but in turn causing some decrease in ultimate car performance because of the extra mass.
Cracking tendencies depends to a major degree on the type of cast iron used. Gray CI is the most prone to thermal stresses because of the sharp-edged nature of its graphite flakes. "Ductile" or 'nodular"CI is much less prone to thermal stress cracking because its graphite is shaped more like lumpy raisins - it doesn't have the sharp edges that gray CI has. Compacted Graphite Iron is even better, since its graphite is more of a "ball of worms' structure, but so far is not commonly used because of its extra expense and the fact that there are not that many foundries that pour it, at least on a regular basis.
Believe it or not, many/most of the vented rotors you see are still being done in gray CI, partially because of it's ability to flow through thin sections in the mold much more easily than ductile. The highest level vented rotors are being done in CGI, but will cost a lot extra.
What can actually be used as the minimum thickness will ultimately be determined by a combination of the thermal stresses and the mechanical stresses, with both, of course, being partially governed by the maximum rotor temperature. Most FF's with 1/4' rotors are actually under-stressed to a large degree - great for longevity, but in turn causing some decrease in ultimate car performance because of the extra mass.
Richard, Any idea why stainless steel is not used for our formula car brake discs? They seem to have been working quite well on motorcycles for over 40 years.
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Scott Woodruff
83 RT5 Ralt/Scooteria Suzuki Formula S
65 FFR Cobra Roadster 4.6 DOHC
SS is used on motorcycles simply because it doesn't rust - a real no-no to any self-respecting motorcyclist is having anything on their bike not look absolutely perfect, and the sight of rust would put them in apoplexy!
SS works, but has about 1/2 the coefficient of friction (Cf) of cast iron, and about 1/3rd the heat transfer rate, meaning that to get decent braking, they need very aggressive pad compounds that can stand very high temperatures.
brake rotor thickness
