ABS Powerbrake front disc install on my 66 calais coupe

[STDog]

Wasnt the 68 (and maybe 69) disc a 4 piston fixed caliper?

Only on the Eldos. The RWD cars uses a single piston.

[73eldo]

One thing that makes the caliper more low profile is that its a newer design that has its attaching bolts only on the lower back side.  The earlier and mid vintage single piston GM ones had those long bolts up high that went all the way through to the outside.    Its interesting how the aftermarket kit people dont think its necessary to have that cast cage around the caliper like the OE stuff always had.  If you are going to not have that cage I wonder why many even bother to use that older design caliper?  Or why they dont just make an adapter plate to mount an OE cage to go along with the caliper?

[BadBoyRipper]

There is no need to replace a proper-working Master Cylinder/Brake Booster, unless it is a Single Circuit type.

The main thing to do is not to forget the Proportioning Valve in the rear line.

Bruce.

By Single Circuit type, do you mean a single fluid chamber?

[The Tassie Devil (Bruce Reynolds)]

A Single Circuit system has the one reservoir, with the front and rear brakes sharing the same piston

A Dual Circuit system may have a long reservoir, but separate piston pressures for the front and the rear.

Not sure when GM changed from the Single Circuit to the Dual Circuit.

Bruce.

[73eldo]

I think it was 67 and it was a Federal safety mandate.

[Geoff]

Actually it was 1962.
http://www.conceptcarz.com/vehicle/z10927/Cadillac-Series-62.aspx 

American Motors also introduced a dual master cylinder in 1962.

Geoff

[EZ]

Not all cars had the dual MC in 1962.   My '64 Sport Fury and my '65 Barracuda and my '66 Baracuda all had the single pot master cylinder.

[73eldo]

Some may have had it before but I believe that 67 was when it was mandated.   I have seen several of 66's with singles but nothing newer than that.