Wilwood Master Cylinder & No Pedal

[PG Wootown]

Hey people.

So I decided to upgrade my setup and pulled the trigger on a Wilwood MC.

So here's my problem, I did the standard issue bench bleed, and install, but after all the bleeding, the pedal still goes to the floor.

I know there is no air in the system. I read somewhere (jalopnik, or a C10 page... can't remember) that a guy suggested that the front piston in the MC may be stuck or vacuum locked in the forward position.

He suggested blocking the front port and see if I have pedal, and I do. My question is, if thats what it is, how do I get the front piston to release?

Kinda of new to the performance side of things, so thanks for any help you guys can give me.

Matt

[rocketrod]

I am assuming the bore size is the same and you verified there are no leaks anywhere? I just went through something similar when I swapped out a Wilwood MC for a Baer Remaster MC. I had to adjust the master cylinder pushrod to get a pedal with the Baer Remaster. Are you running manual, power or a hydraboost setup?

[Tincup]

If your running manual brakes, the master may be to small to push enough fluid, I just went through this.

[GoodysGotaCuda]

I "knew" i didn't have any air, until I kept finding more. Gravity bleeding, pushing fluid in/out of a full bottle and reverse gravity filling eventually got "it all"

[PG Wootown]

It has a brake booster. The cylinder bore size is correct.
When I blocked off the two front ports on the Prop Valve, the pedal firmed right up.

I followed a suggestion and put a very small amount t of air in the front port and I heard a pop and felt a click. I bled it again, and the pedal now feels spongy instead of going straight to the floor. I'm going to try a vacuum bleeder to get it bled some more. I'm just worried about whether the seal was damaged when it got stuck forward.

[H8rDave]

Well, if it was moving fluid, so that you could bleed the front brakes, then it wasn't stuck. Which doesn't mean it doesn't suck. JK, don't hate. there is still air in the lines. lots of it. Even though the lines were full from the old master, when swapping to a new master it will take at least 12oz of fluid through each port to get the air out. Then, drive it around and bleed it again. (unless you have a pressure pot). Filling the little 3oz bottle wont due, unless you do it 4 times per corner. Now everybody, from the song La-Bamba, "......and again and again, come on let's do it again".

[AMC Racer]

OE master may have had primary port (front brakes) to rear port of master (nearest firewall). If it's the Wilwood tandem master w/one-piece cast aluminum housing, it uses the front port (furthest from firewall) as primary port for front brakes. Which ports do you have your lines connected? Primary port A has twice the volume (longer effective stroke) of port B so goes to front brakes. If connected opposite, pedal will likely go to floor.
https://www.wilwood.com/Images/MasterCylinders/MasterCylinder_Drawings-Large/260-8555-BK_dwg-lg.jpg
https://www.wilwood.com/PDF/DataSheets/ds487.pdf

Hope this helps.