I recently read a newsletter account of a gentleman who had wild ride at a Time Trial. His car passed tech inspection, he was on course for a time trial event (at Shanandoah), braking at the end of a straight, and suddenly had no pedal. His foot went to the floor and he went off course. The end result was luckily only a banged up car, he was O.K. The failure was a flare fitting at the end of the crossover tube on one of his calipers. He indicated they were "monoblock", but no brand names were mentioned. My question is this; Why is an external crossover tube still used in modern calipers? Isn't there a way to integrate this into the body, protect the coupling and reduce the chances of external forces creating a failure? Some input from those in the know (Stoptech or others) would be appreciated.

 

it would have to get awfully hot if it ran internally....

I've never hear of a x over tube failing...there is more to the story I bet

 

Until now I hadn't either, but it still brings up the design issue in a dramatic way - why have 2 external fittings and crossover if it can be done internally? The exposed tube is susceptible to vibration, corrosion and foreign object damage that could cause failure, but still seems to be universal practice. With the machining capabilities available today it seems kind of archaic to have it external. Perhaps JRitt or someone else with brake system engineering support could comment. Just curious.

 

First thought that comes to mind is that the better calipers are two parts, NOT MONOBLOCK. It has been demonstrated that a steel connection between the two opposing piston housings is superior in strength and fatigue resistance. The entire caliper is normally very protected by riding inside of the barrel of the wheel so the likelihood of damage by anything is quite slight. I have yet to be teched by anyone who even glanced at my calipers with the thought of a damaged Xover tube. If there was an actual benefit of an internal Xover connection between the two halves of the caliper it definitely would be standard practice by now. As Z1 has surmised, I sure that some other more human factor type cause was the culprit here.

 

I read somewhere that one advantage of the external piping is that the heat from the brake fluid in it dissipates easier than one that is entirely internal.