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Grady Clay Grady Clay is offline
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Join Date: Dec 2003
Location: Arapahoe County, Colorado, USA
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Bill, I agree that brake system flex is an overall issue. Yes, brake hoses are only part of the equation. In this case, I feel that the built in hysteresis is desirable, not an “ugly head.” Hysteresis is dampening of the pressure cycles. Tires have hysteresis, shocks induce hysteresis, rubber suspension bushings have hysteresis (plastic bushings reduce it), even the deformation of the road/racetrack induces hysteresis. A railroad wheel-to-track has very little hysteresis compared to a car. Railroad trains build it into the ties-to-ballast.

I have driven and raced many Porsches with both extremely rigid systems and moderately flexible systems. I personally like slightly more flexibility in a 911 (or 935). For the 911 owner who isn’t testing the limit-of-adhesion every time the brakes are applied, softer is clearly better.

The diagram you posted is what? It looks like the working or burst pressure limit (0-80 bar) for various sizes of hose (-20 to -6) vs. temperature (0-260 C). What we are talking about here is -2 or -3 Teflon/stainless hose rigidity vs OE rubber/fabric hose rigidity at Porsche operating temperatures.

HarryD is correct. With the SS fabric you can’t tell if the PTFE hose underneath has been damaged. For the uninitiated, I would prefer to err on the side of original equipment (OE or OEM) unless absolutely convinced otherwise.

Best,
Grady
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Old 01-07-2004, 02:38 PM
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