Pressure Bleeding Questions
Thread Starter
Instructor
Joined: Oct 2008
Posts: 117
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From: Townsend TN
Pressure Bleeding Questions
Does pressure bleeding the brakes preclude the need for a THOROUGH bench bleeding of the Master Cylinder? I did try to bench bleed my new 1994-200x camaro master cylinder, and at one point, went on and mounted it to my 87 corvette booster (do not currently have bench vise) and followed the directions by pumping brakes and watching until the air seemed to have been bled out. I have also replaced mid section of lines (no leaks evident), bypassing the ABS, and have utilized over 4 qts of Wilwood racing fluid, but still seem to have air in the system, as the pedal still goes down over 1/2 way after building pressure at top of travel as expected (then slowly going down with serious pressure). This all after 2x through all wheels using a pressure bleeder with a good 10psi + seal at the master cylinder cap/top. I have wilwood 6 piston lites front and stock rear calipers (both with aggressive pads), and bled them all, in correct sequence until no more air bubbles. oh yes, and of course have braided lines at each caliper...Any ideas?
Thread Starter
Instructor
Joined: Oct 2008
Posts: 117
Likes: 0
From: Townsend TN
Le Mans Master
Joined: May 2004
Posts: 5,385
Likes: 534
If you can get access to a vice, go for the bench bleed. I had an old master cylinder I wanted to use to "get by". Before I changed my mind and just purchased a brand new one, I bench bled the old one and there is a lot of air in it, you would be surprised.
Safety Car
Joined: Sep 2004
Posts: 3,953
Likes: 550
From: Mission Viejo CA
Since you replaced the master, did you adjust the length of the pushrod between the booster and the master? This may affect the stroke of your brake pedal. Remove to cap of the master (if you have two, the one closer to the booster). While standing on your left leg outside the car, and your right foot on the brake pedal (engine off), press slowly on the brake pedal. You should see an immediate jet of fluid that will disturb the surface of the fluid in the reservoir. If you need to press the pedal more than about 1/4 to 3/8 inch, your pushrod is too short.
To adjust the pushrod, move the master forward out of your way. Pull the pushrod out of the booster a little, so you can grip the shaft with pliers. Adjust the hex end of the shaft with a small wrench.
If the pushrod is too long, you won't see the jet of fluid, and your brakes will drag when the car warms up.
To adjust the pushrod, move the master forward out of your way. Pull the pushrod out of the booster a little, so you can grip the shaft with pliers. Adjust the hex end of the shaft with a small wrench.
If the pushrod is too long, you won't see the jet of fluid, and your brakes will drag when the car warms up.
