[hdpontiac]

I have a complete disc brake set up with spindles from a 69 GTO would that fit the 65 GTO without any problems also would the offset be the same,then I would like to change the single master to dual anything special that would have to be done to make it work.

[Goatracer1]

I used 1971 on my 1967 with no problems. I did need a smaller bore master cylinder than the one I took off the other car but it bolted right on my booster. The system worked with the first master cylinder but it required a lot of pressure.

[Lemans64]

That system is what is in my 64, works very well in my opinion. Retained the rear drums so no modification for the parking brake.
You will require new type Combination valve or the prop valve from the 69, I used a new style on. Available on Ebay. Or and Brake tubing place.
There is 2 master cylinders available, one has deep hole and one is shallow hole in back where it bolts to booster so check booster rod for length
before ordering master, Can check old master to see if it has shadow hole or deep. I do believe the disc system puts wheel out 1/2 inch but not positive on that.
you will have to make up brake lines for new system. Rear Line from new combo valve uses 1/4 and large fittings, so some adapting is required. I just used a master from a 69 with disc brakes,
I believe it was 1 1/16 bore size. Manual brakes use smaller bore. Also hole for pushrod is different for power so if swapping from manual to power the
pushrod goes in lower hole for power brakes.

[AG]

I used a set-up from Right Stuff for '64-'72 A-body with a Wilwood 1" bore master/proportioning valve and it works great.

[geeteeohguy]

What Lemans 64 said. Installed '72 Cutlass spindles and discs on a '65 GTO years ago and it was a straight bolt-on. Used the master cyl, etc. from the Cutlass. No steering angles changed at all. IMO, this is a much better swap than the aftermarket kits with the adapters used to mount the calipers, which seem to have issues.

[AG]

The kit I used was exactly the same as a GM disc set-up, no adapters.