Re: Strange Brakes
Posted: Mon Jul 30, 2012 5:29 pm
simonknee wrote:So re-reading all the info in the thread the bit the still doesn't fit is: if the vapor of boiling fluid is causing a FTTF then why do a couple of pumps firm things up?
This is all really interesting since knowing what happens in these scenarios, and how to react, is potentially life saving.
My thought on that are that the vapour whether it be boiled fluid or water vapour driven from the fluid, will be in the brake cylinder the nearest point to the heat source; when you release the brake pedal the expansion of the vapour is not as quick as the normal retraction of the brake piston, so the fluid in the pipe does not move back to the master cylinder as quickly as normal, this causes the master cylinder to draw in some small quantity of fluid from the reservoir.
Repeat pedal release & re-press a couple of times and you have enough fluid in the system to compress the vapour to small dimensions and you gain a somewhat spongy brake performance.