Posted by john eickhof [188.8.131.52] on Thursday, February 09, 2023 at 20:02:39 :
In Reply to: brake bleedng posted by Jerry in Idaho [184.108.40.206] on Thursday, February 09, 2023 at 15:25:49 :
jerry, yes, vacuum bleeding can be done with or without drums, the principal is simple, the hand vacuum pump uses very little vacuum or suction to pull fluid from the res past the return port in the mc then draws fluid and air towards the point at which it is connected, ie wheel cyl, however, you need to bleed in reverse order of pressure bleeding by starting at the closest wc point to the mc to draw out air there first, then go to the next farthest wc etc until you are at the farthest point wc then bleed until no air is present. i use a one-man pressure bleeder myself, and have for over 40 years, i did brakes for a living for decades, the vacuum unit is not strong enough to pull air past the cups unless there is a blockage in the line or the mc is out of adjustment and the return port is not clear so dont worry. the old gravity method works well too but will leave air pockets in the wc or other devices (like a mico brake lock ) like proportioning valves and system protectors. also it takes several days to gravity bleed with sure success. also, if gravity bleeding, do one wc at a time and just crack the bleeder otherwise fluid may flow to fast and you will pull air back in the mc! have fun!
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