Disc Brakes . . . Completely Utterly Frustrated

I've got the MC for 4 wheel discs, so I'm supposedly good there.

Today, I DID learn that I have a whopping 500 PSI at the front calipers (should be 900-1,200), so . . . I think we're narrowing down the problem.

Latest update:

We put a pressure gauge on the fronts, rears, and directly at the master cylinder. Max on the rear was 500 PSI. Max on the fronts was 800 PSI, but it was both feet on the pedal and breaking the seat back. Pressure at the master cylinder wasn’t different, so there’s no blockage.

Wilwood states they need 900 to 1100 PSI for relatively normal operation, so I’m not even really close there. And I figure the rears aren’t going to be much different. So, long story short, the master cylinder isn’t even close to working with my setup EVEN THOUGH it's advertised as exactly what I need.

So, we call ABS Brakes (they make the units for Scott Drake), and they say that the unit has a dual diaphragm booster, and I should be making plenty of power. After about 30 minutes of on the phone troubleshooting, I send a picture of what I have to ABS. Low and behold, it’s a single diaphragm unit, which is wrong for the part number I ordered. That’s actually the good news. The bad news is that I bought it through Summit, so I had to return it to them and HOPE they send me the right part. ACTUALLY, they did . . . the marking on the box was wrong, so either Scott Drake mislabeled it or it was made wrong at ABS.

We decide to send the unit back to Summit for credit (it really WAS the wrong part number, so nothing dishonest there), and we’ll buy the right unit from ABS.

All is well with the world.

NOT EXACTLY!

As we’re wrapping things up, a little detail comes to light. While, YES, the pedal will feel much lighter and be more pleasant to drive, the right unit WILL NOT have more hydraulic pressure. So, we just spend 45 minutes to go from “the pedal is hard and the car won’t stop” to “the pedal will most likely be very pleasant . . . but you still can’t stop the car”. *sigh*

ABS said they can custom fab me a system with a dual diaphragm booster and a 1” instead of a 1 1/16” master cylinder, and that should do it. Wilwood recommended a 1” MC so I’m encouraged here.

We’re in process of removing the MC/BB and sending it to Summit. When my card is credited, we’ll order a “custom” unit from ABS. I’ll let you guys know how that works.

We have a path forward, but I’m disturbed by one thing. I bought a MC/BB that was designed to work with a ’65 Mustang with both 4 wheel discs and a manual transmission (which I have). It didn’t . . . at all. I asked ABS “so, if this is designed for what I have, what components would I need to change to make it work?” I didn’t get a clear answer . . . or one at all. So I’m still left with the question of “why didn’t the one I bought work . . . at all?”

Guys, I can’t tell you have frustrating this is because I can’t be the only person doing this. If anyone else has this MC/BB and can put a pressure gauge on the outputs, I’d be curious to see what you get.

Excellent observations my good man!

Wilwood recommended that setup to me, as well.

I found out the same thing i.e. there are different pedal setups for a manual and power system. The power systems have something like a 3:1 ratio while the manual systems are 5.5:1. I REALLY wish this would have been addressed somewhere in the part description before buying it, but I digress.

I, like you, have the manual (5.5:1) setup.

What I’m about to do is go in a different direction. I had a friend I work with put me on to Baer brakes. Now, there brakes are top of the line, but way out of my price range (right now), plus, eh, what I just put on is pretty good. So I called them, and they talked with me a good 15 minutes on how to address what I already had . . . AND DIDN’T TRY TO SELL ME ANYTHING! They really were trying to help me get all of this non-Baer stuff working together. That was impressive. I told them that I wanted to drop the current MC/PB and put in one of their manual “Remaster” setups, and they pretty much told me that it would put out way more than I needed and a 1” or 15/16” piston was in order. It’s pretty much a direct bolt up, and the price was right. So, the current plan is to pick up one of those when Summit gets the Scott Drake unit back. I’ll let you guys know how it goes.

The guys from Baer and from Wilwood were aces, though . . . great response.