I installed front disc. Brakes on my “54” truck with a new master cylinder and booster from CPP and now I am having trouble getting a good peddle. I bench bled the master cylinder and have used both a hand pump and manual bleeding to get the air out but just cannot seem to get a solid peddle. I have read in some post about “valves” in the lines to keep the fluid from going back to the master cylinder since it is below the level of the calipers I know this is a common swap with the master cylinder/booster so can someone tell me what else to check, what have others done if they had this problem? Thanks
The only reference I have heard of valves in the lines is when the inner lining of the rubber hose comes loose and acts as a check valve, which can happen. If it has been that way since you installed it and you don't have any leaks or anything, then I would say you have a bad master cylinder. I got a bad one from CPP and they replaced it no problem for me. Got the replacement new one installed and bled and all is well again.
The " Stick Trick " Is what I do when faced with this occasional problem : Get a stick and wedge it between the brake pedal and the dashboard , leave it there for 48 hours minimum , this allows the by-pass port in the master cylinder to be uncovered and ever so slowly , atmospheric pressure will draw out those last few bubbles that are causing you soft pedal . It also works great on old Motos , just rubber band the brake lever to the handlebar overnight and get that rock hard brake feeling again .
Residual valves. Install betwen the master and the front or rear lines. 2# for disc, 10# for drums. It keeps the fluid from flowing back to the MC when mounted under the floor and keeps enough pressure on the calipers to keep them near the rotors. https://talk.classicparts.com/showthread.php?t=12960
Soft pedal ? Soft pedal means air bubles in your new system or a leak some place. Did you remembered to install the residual valves to keep the pressure up in your brakeline system, if not install 1 in front and 1 in rear in a good straight angled position ? This issue whas up this week and i wrote a lot about it. Ol Chebby has attached a link to it in this thread. As you allready have finished your new brake setup i am very intrested to learn from you! What i wanna ask you about is , as i am partly going to do the same operation is that you explain to me how you have connected the CPP dual master cylinder together with your excisting brakelines? Could you be kind to tell me wich size and what kind of fittings you have been using there? ( part number and model ) please. Attached the catalog with needed fittings; http://www.plews-edelmann.com/brochure.cfm?brochure=1869&location_id=2516 My new setup will look like this; I am going to keep the rear and front drum brakes and use the new CPP power brake booster with dual master cylinder but without the proportional valve. I wanna use the standard brakelines i allready have there because they are new. But connect them together and intergrate 10 Lbs residual valves , 1 in front and 1 in the rear. Thank you helping me out here! Martinius.
Blueflame as I mentioned in my post I went with the disc. upfront but all I did to replace all my lines was used the old lines to make a pattern as close as I could to the master cylinder and than I used a coat hanger to bend to get what I needed to attach to the master cylinder. After I got the length of line I needed it bought strait lines in the lengths I needed with the proper fitting already on them and bent them to match my patterns. Nothing to it!!! Good luck
Not saying this has ever happened to me before. But make sure you have the right side wheel cylinder and the left on the proper sides.Otherwise you can end up with the bleeder not on the top.. my buddy did this on a 4 wheel disk conversion on his jeep.. we bled for hours before a friend told us to check for this...
Get the correct fittings nd you could just come out of the MC with the Res. valves, then thread your brake lines into them, not having to cut any of your existing lines.
