[OZZIEVILLE 67 2 door]

I did a disc brake conversion on my all drums 67 Bonneville many years ago.
The kit was sourced downunder and a local brake shop fitted it.
They worked but were never powerful but I put up with the weak performance as I had no brake fade issues.
Disc callipers are Ford twin piston type.
Reconditioned power boster.

I did not change out the master cylinder and always intended to.
I nearly hit a car in a roundabout last week due to speed the car entering and me not having any breaking power in reserve.

I have purchased a new period correct GM disc master cylinder and the break line ports are a different size.

My question is, can I make this work.
Is it as simple as a new brake line, even a flexible steel, from MC to proportioning valve, or is there an adapter to screw into 1/2 inch port to except 7/16 fitting.
If you know what I mean.
Thanks, John L


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[Scarebird]

what size are the pistons, both master and caliper?

[vertigto]

Interesting...having the same issue with a conversion from Right Stuff that uses 94-’04 Mustang Cobra dual piston calipers/pads.

Which application are your Ford calipers for?

FWIW...they just sent a new MC with a smaller 15/16" bore. Will be interesting to see if that solves a very dangerous situation.

[mgarblik]

If fitting the existing line nuts is the only issue, there are all kinds of adapter fittings to make almost any line fit any MC. Even different flare styles, ISO, vs double flare vs Bubble flare. A good parts store should have adapter fittings in an assortment. Here is 1 of many sources: https://www.agscompany.com/collectio...ng-assortments

[OZZIEVILLE 67 2 door]

Originally Posted by Scarebird

what size are the pistons, both master and caliper?

Thanks Scarebird , MC bore is 1 1/8 and callipers piston bore 1 5/8 or 40mm as best results to my research.

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[OZZIEVILLE 67 2 door]

Originally Posted by mgarblik

If fitting the existing line nuts is the only issue, there are all kinds of adapter fittings to make almost any line fit any MC. Even different flare styles, ISO, vs double flare vs Bubble flare. A good parts store should have adapter fittings in an assortment. Here is 1 of many sources: https://www.agscompany.com/collectio...ng-assortments

Thanks Mike
My small country town lost its only dedicated brake shop a few years ago , just means I will have to travel a bit.
You don't miss them till you need them.

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[Goatracer1]

The fittings you need are available on the internet if you look around. What size bore was the master cylinder that did not work for you? You probably need a master with a 1/8 inch SMALLER bore to increase pressure to your brakes. The smaller the bore the higher the pressure. I had the same problem with a GTO years ago and recently with a Bonneville someone else built.

[Scarebird]

Originally Posted by OZZIEVILLE 67 2 door

Thanks Scarebird , MC bore is 1 1/8 and callipers piston bore 1 5/8 or 40mm as best results to my research.

The master is way too big; 15/16" would be better. I am not sure if a 24mm Mopar master would fit your booster even with modding or if available in Oz.

[OZZIEVILLE 67 2 door]

Thanks Goatracer.
That explains why the rear port on the new MC is 7/16 and the front port 1/2 inch.
It's a fitting I need to male 7/16 to screw into MC the with the female 1/2 inch to receive steel brake line..
What do you call this fitting and thread name/size
JL

[lust4speed]

Originally Posted by Scarebird

The master is way too big; 15/16" would be better...

Friend's Wilwood disk brake conversion has a hard pedal. It feels more like a booster going bad so we will do that first, but is there a formula for preferred wheel caliper area vs master cylinder area? Trying to decide whether a change from 1-1/6 to 1" or 15/16" would be better. Worrying about excessive pedal travel.

[Skip Fix]

Speedway has a lot of brake line adapters online.

[HoovDaddy]

I installed a Right Stuff kit on a '67 Impala a few months ago and had the same pedal problem (same brake system as yours). I noticed your booster is flat against the firewall. Most of these fits for those B bodies have brackets that change the angle of the booster on the firewall so that the pushrod has a straight shot from the pedal to the booster/master cyl and doesn't bind. I changed the rod location on the pedal and had good pedal feel. Look at the angle of your rod from the pedal to the master. I have also ran into the push rod length being too long and the piston bottoming in the master cyl.

I assume you have enough vacuum to operate the booster and that your rear brakes are adjusted.