Quote:
The braided part of a braided line does little ( if any ) control of the line expansion under pressure. It's just a protective cover from external abraision.
this is absolutely false. the braid is an integral reinforcement to the teflon lining. brake lines work at a few thousand psi and teflon itself would not hold up. the braided brake lines are different than the braided fuel lines. the fuel line braid is there for aesthetics and abrasion resistance. the brake line is braid is there for strength. that being said there are various braided hoses manufacturers and having tested most there is a wide difference in quality between them. the braid needs to be flexible but tight on the core and some of the hoses we worked on had double braided layers.
hoses are designed to move when the braid packages are considered they are designed to swell and shorten as well as some amount of twist is acceptable. this is fine when used in a hydraulic system. its not fine when your using it in a brake system with a limited amount of pedal travel and master cylinder piston/stroke volume.
For those that had a the spongy pedal i would surmise that the extra volume added by the hoses was identifying the limit of the master cylinder if you went with a larger bore master the spongyness would go away, again this a guess, and would need to be tested. as with all engineered hydraulic systems it is important to consider the entire system when selecting parts, most racers don't and very few people actually understand hydraulics.
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