Gap Between Booster Push Rod and Master Cylinder

[Gratefuldiver]

What's the gap I'm looking for here? I measured mine and had almost .070. I felt that was a bit much so I reduced it to about .030. That sound ok? I've been battling trying to get these brakes bled for some time and can't get it done with the paddle. Yet if I pressure bleed, I get the pads to bite down on the rear rotors but not with the pedal.

[Apogee]

I would say .030" is good, maybe a little on the high side of okay. I generally aim for about .015 to .020 give or take as it minimizes the dead pedal distance and still allows for the complete release of the brakes under normal operation.

I'm not sure what your bleeding issue is, but I'll ask the obvious...did you bench-bleed the master cylinder? What method, recirculation or plugged-port? If recirc, did you confirm it was fully bleed by plugging the ports and confirming hydraulic lock? Otherwise, some systems just don't bleed easy.

Tobin
KORE3

[David Pozzi]

I read somewhere it's .010"
With an angled master cylinder you need to bench bleed. You might get away with jacking the rear up as high as you can, also bleed the lines at the MC by cracking the lines open, but cover them or they can squirt fluid around.

[MCB Matt]

Are you running a prop valve? What master? What booster?

Give us a better idea of your setup and we will have more to go on, different systems have different issues.

Matt

[MonzaRacer]

Need to know what master cylinder fittings are thread size, then buy inverted flare plugs and block it off and see what it feels like. If its high and hard, your master cylinder isn't at fault.
Then to be one way too identify issue is add each wheel back in one at a time. You can do this closer to master cylinder or farther. Too identify issue break it into small sections. Till it gets all spongy, then there is your issue.
I had owner of shop bring in a Dodge journey with low pedal,thought abs needed bled.
Turns out the right rear caliper was locked up. The other shop he has didn't find it,and these people are supposed to be professional mechanics? There usre found worn front brakes but missed rtrashed caliper piston boot, or fact caliper was all loose and foppy compared to other side.
You can make your plgswith small section of line and fitting. You simply either smash or fold over line couple times, or weld or properly solder it shut. This should narrow down where air issue is.
I don't really think the play will affect pedal feel you will just feel the take up before you start braking.
BUT if it keeps master cylinder to go full stroke giving poor performance or poor bleeding.

[Gratefuldiver]

I forgot about this tread lol. Ive tried bleeding everyway known to man. Yes Ive bench bleed (several times) Ive pressure bleed, 2 person pump bleed, gravity, and suction. Its like I have a leak but am not leaking fluid. The last pressure bleed I did I used a weed sprayer type plumbed in to the wilwood 1" tandem master. I put about 25-30 psi (constant from compressor) on it and ran about a gallon of fluid through the rears. The calipers/pads clamped down good on the rotors and I had no air coming out the rear. So I removed pressure from the bleeder and unhooked it. With in a few pumps of the pedal it was soft again and wouldn't clamp down on the rotor. This is not my first time doing a brake job lol so it has really pissed me off I cant get it done. To the point Im replacing everything front to back.

The master was already new and if I cap all the ports it has a nice hard pedal and doesn't get soft so Im sticking with my master. Ditching the stock disc/disc combo proportioning valve for a tee for the front lines and an adjustable Baer unit for the rears. Replacing the stock 1/4" SS line with 3/16 front to back, and replacing all the flex line (3) on the rear as well as the hard lines on axle. The rear calipers are new but just to rule them out, I exercised the 90 return policy with Summit and had Wilwood send me a new pair. If I cant bleed it with all new stuff I will pay someone I guess, because Im at a lose. Im the butt of all the jokes in my local Pontiac group on top of it all LOL.

[bryant]

what type of calipers do you have?
some kits have the calipers clocked with the bleeder port below the 12 o clock position. they require the caliper to be unbolted and rotated so the port reaches the 12 o clock position.
some disk brake calipers with a parking brake built in need the parking brake manually adjusted before they will deliver a hard pedal.
you have wilwood rears, and those usually dont have these problems.