bad brake pedal, help with diagnosis please

[Jerryl]

FWIW

The "T" may not be the best return solution. A seperate return via reservoir replacement is the best solution as this will slow down the velocity and give the air a chance to seperate.

Next best solution is to drill your expensive and impossible ro locate reservoir, and add a 3/8 barb, as high as possible BUT 0.5" below cold fluid level.

Last best solution is "Y", not a "T".

 

[Toby_Goodmk]

More info along the same lines.
Never got the brakes to work right. Power assist (HYDROBOOST) section appears fine.

Ended up having 4 bad master cylinders in a row.
How? Don't know.
Confirmed? After bench bleeding each, I plugged the ports at MC on the car with some metal fittings I made. Engine off, pedal starts out hard but keeps dropping about 1/2 way down.

Waiting for a MC from Wilwood.

Here is something intetesting:
Most available MCs have the rear brakes going to the primary circuit. I firmly believe this is absolutely incorrect and Buick had it right on the PM units. You want the front to apply first or the car can lock the rear tires and become unstable.

The Wilwood MC to use as a direct swap when going from PM to HB is from a Chrysler. Not the prettiest or sexiest looking thing but it's all thats available.

Hope this helps.

View attachment 279747

Why arent you using the cast Iron steel unit from an 84? It applies correctly.

 

[Jerryl]

Why arent you using the cast Iron steel unit from an 84? It applies correctly.

Because unlike many, I like to obsess and do things the hard way.

Seriously though . . .
I did not like the look and the lines are backwards.

 

[Toby_Goodmk]

yea, my neighbor and I have been discussing this while I had all the issues with the bleeding, and the HB, he said the same thing, you have the lines reversed. I said no....the fittings only go on one way. I wonder if this is something to do with your bad pedal? And yes, it is quite ugly...but I will tell you now my brakes are badass.