[DeTomaso] Stock Brakes

[SOBill at aol.com]

Air will collect at any place in the brake lines where  the fluid must go 
from a relatively high spot to a relatively low spot. At the  front wheels, this 
situation is exemplified by the brake hose section which goes  up from the 
hardline/hose transition fitting and then down to the caliper. Air  will want to 
remain at the highest location in the  system.
 
If you can push a lot of fluid at a high rate you can, sometimes,  flush this 
trapped air downhill and out the caliper bleeders. But the brake  lines are 
quite small in diameter, not much fluid actually gets moved, and air  
definitely does not want to go downhill. You can have what looks to be  bubble free 
fluid coming out of the bleeder and still have air at a high point  in the 
system. The air stays at the top and fluid just goes past the air on the  lower 
surface of the hose. You can easily see happening if you do some fluid  transfers 
using clear tubing.
 
A second approach is to dismount the calipers, block  the caliper pistons 
from movement with a piece of wood, and position  the caliper such that the 
hose-to-bleeder path is all up hill. By gently  tapping on the 
hose/fittings/caliper while slowly pushing the brake pedal down,  you will get all the air to the 
top of the system and out the bleeder  screw.
 
It helps to imagine where an air bubble would go if you  want to completely 
fill a fluid system such that it is free of air.  How much pedal travel you 
have and how spongy the pedal feels is simply a  measure of the percentage of 
system volume is still filled with  air.
 
Have fun, 
 
SOBill  Taylor
sobill at aol.com



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