Wilwood master cylinder with standard brake setup

[Formula50]

I have been working on my roadster that I bought recently (build/rework thread soon!). Getting the brakes sorted is on top of the list and had hoped it would all be fine, but I need some advice.

First of all the current setup:
Front disc brakes, regular Fox body, 2.35" cylinder bore
Rear drum brakes, standard Fox body
Wilwood master cylinder (I'm guessing 7/8")
Maximum Motorsports pedal with original pedal to master cylinder connecting rod (MM connecting rod was waaaay too long to fit)

So... the braking has never been too good on this car, as the PO told me. Didn't surprise me too much since the pedal mod wasn't done yet so that's what I set off to do first. I was sure that would be the fix, but no. At least not for now...

What did I do? Installed the Maximum Motorsports pedal and installed new seals and dust boot in both front brake calipers. Bled the system and that's where I figured out something was not quite right. I just can't get enough pressure on the system it seems. The rear wheel cylinders move a little bit, but doesn't press the brake shoes outward enough to really grip the drums. Same goes for the front discs. I can see the piston move slightly, but can still turn the wheel by hand when the brake is pressed. Bled the system by starting with the wheel furthest away from the master cylinder and also checked the brake balance adjuster. Never had any problems bleeding brakes before, so I'm confused.

What it looks like to me is that the Wilwood master cylinder in combination with the pedal is not moving enough fluid to get the system to work. The piston in the brake master cylinder just doesn't seem to move in and out far enough to build enough pressure. Well, that seems to be my conclusion so far. My next step would be to install a standard Fox body master cylinder and see if that would get the brake system going. Would that be the right step forward? What do you guys think? Am I missing something? Is the Wilwood master cylinder indeed not compatible with the standard brake setup that I have? Is the pedal stroke too short to get this working with these parts?
I'm not blaming anything on the MM pedal or Wilwood because they're both very solid products, I'm just thinking something in my setup doesn't work together too well.

Also, if I go to a standard Fox body master cylinder, what bore size would be the best? I think smaller bores generate more pressure and thus require less pedal effort. Would it be smart to go with a smaller bore since I have no power brakes?

Thanks!

[Gordon Levy]

That's is not the issue. Off hand I would say there is still air in the master. The components you have will work just fine together.

[Formula50]

That's is not the issue. Off hand I would say there is still air in the master. The components you have will work just fine together.

Good to hear the parts should work together well. I’ll get the master cylinder out again and bench bleed it thoroughly as a first step. If that fixes it that would be the best case scenario since I know they’re quality components. Thanks and I’ll keep this thread updated.

[CraigS]

I agree. One technique a lot use for bleeding the Wilwood MCs is to bleed one front and one rear at the same time. The problem can be this. You get some function in both MCs. For discussion say you try to bleed the front MC but the rear MC stops moving, the adjustable balance bar moves at an angle but that angle has a limit. So your front MC stops moving before it moves it's piston all the way to the end. Hence air bubbles never leave that MC.
https://live.staticflickr.com/65535/49749270886_f614edbdbe_z.jpg (https://flic.kr/p/2iNb1ZL)Wilwood balance 3 (https://flic.kr/p/2iNb1ZL) by craig stuard (https://www.flickr.com/photos/152454123@N04/), on Flickr
Ignore the arrows, they were for another purpose. But see how that balance bar is no longer at 90 degrees? Two possible solutions are; 1- open a front bleeder and a rear bleeder at the same time. Of course this takes three people. 2- The easier is to pressure bleed. I found a piece of radiator hose that would fit over the top of the reservoir and went to the hardware store to cobble up stuff to reduce that diameter to something I could connect to air pressure.
https://live.staticflickr.com/4588/39320475642_8b0a91d4fd_z.jpg (https://flic.kr/p/22UBHvd)Pressure Bleeder (https://flic.kr/p/22UBHvd) by craig stuard (https://www.flickr.com/photos/152454123@N04/), on Flickr
You only need a max of 10# pressure so go to a pet store and buy the least expensive fish tank air pump they have. You can do this w/o helpers because you open just one bleeder at a time. BTW I expect you can get usable brakes w/ what you have but I'd start planning for a rear disc upgrade. Technically you can get drums to work. The problem is that there are a world of pad compounds available but shoes for drums basically come in a 'whatever' compound and no one seems to even know what they are. Pad compounds can transform FFR brakes.

[jrcuz]

Wiwood has a couple videos on their youtube channel showing their method for bleeding dual m/c setup.
JR

[Formula50]

Thanks Craig and Jrcuz. Pressure bleeding would be ideal, but I have the big dual master cylinder and not the separate smaller Wilwood reservoirs, so I don't know if that would work.

Some progress so far: did what Gordon levy told me and got the master cylinder out again and bench bled it thoroughly. I mean THOROUGHLY. I didn't have time to put it back in the car and start bleeding the brakes again, so I decided to leave it off the car for now. When I unhooked the lines after bleeding it the master cylinder dripped every second or so from the holes where the brake lines hook up. If fluid can leak out then air must be able to get in, so I don't want to leave it sitting for days. Just to make sure I'll bench bleed it again before I install it and then go straight through with bleeding the brakes. Just to make sure everything is 100% ok since I don't want to pull the master cylinder out again and can confidently say there is no air in the system anywhere. I think I'm on the right track now since there was some air coming out of the master when I bled it. I'll keep you guys posted.

[CraigS]

Ooops on me. I assumed when you typed Wilwood you had the dual setup. That old saying came true again. Still I really prefer pressure bleeding. If you use the pump the pedal technique I have a pointer. Have your helper do the pedal pushing and be sure he does exactly what you say. With bleeder wrench handy tell him 'pump it up and hold'. At the beginning he may not really get much pedal firmness but hold his foot pressure anyway. Have him say 'holding' when he stops pumping. You open the bleeder and close it while there is still some flow. The idea here is that air can leak back in around the bleeder threads when the bleeder is open so he must not release the pedal until you tell him to after you have closed the bleeder. So the cycle is, 'pump it and hold', 'holding', open and close the bleeder, 'pump it and hold', etc. Good luck.

[michael everson]

Are you absolutely sure the front calipers are on the right side? The bleeder should be pointing straight back not straight up
Mike

[Formula50]

Promised to post the results here, so here we go. It turned out there actually was air in the master cylinder. I bench bled it twice, once a week ago and then again yesterday before putting it back in. To say it was bled thoroughly would be an understatement since I wanted to 100% rule out there could be air still trapped in the MC.
All good and well! I have a brake pedal again and will find out how it brakes during driving soon. Maybe one day I'll convert to power brakes, but for now I'm going with this! Thanks for all the help, greatly appreciated!