Making your GTO (or any '64 to '72 A body) stop better is a fairly simple project, and there are several ways to accomplish the task. Front disk brakes and dual master cylinder are the best bang for the buck mods you can do to a drum brake equipped car!

The easiest swap is to take the spindle and brake parts from a '69-'72 A or G body. (The '67 and '68 will swap in too, but they use the obsolete and problem prone dual piston calipers, with little or no parts support) It is a direct bolt in conversion on any drum brake car. You must also get the proportioning valve and master cylinder from the doner car, as well as the hard lines and hoses. Personally, I would replace all of the lines and hoses at this time as it is cheap insurance! Chances are that you still have the original 30 plus year old steel lines and brakes are no place to scrimp! Pre bent replacement lines are available in both steel and stainless steel. Inline Tube, and I'm sure others, make pre-bent tubes for this conversion......just tell them the particulars of your conversion (I.E., mine has an F body, dual master cylinder, proportioning valve mounted on the frame etc.) and they will send you pre-bent/flared lines with all of the right fittings! Awesome! I used Inline tube for my brake lines, and I am very happy with the product .

Proportioning valve and S/S lines installed on the frame. Pay no attention to the dust!

Another thing to remember when ordering brake lines is what rear you have in your car! My car is a '66, but it has a later rear, which is 1" longer than the earlier one. I forgot this detail when I ordered my lines, and the hard lines on the rear axle were each 1/2" too short! DOH! I called inline tube and explained it to them, and after I sent the wrong ones back, had the right ones in a few days. Very nice people to deal with!

Another way to skin the proverbial cat is to use second generation F body spindles. This conversion is a bit more involved than using the '69 to '72 A body disks. Any spindle from a '70 to '81 F body will work, but the best ones are the '77 and '78, as they are lighter than the earlier ones, and the later ones use some metric parts.

Front suspension parts ready to assemble......Hotchkis Tubular uppers, '78 TA spindles and stock lowers.

There are 2 options when using the F body spindles. You can use the stock A body upper control arms or use aftermarket tubular uppers (Hotchkis or Global West). The aftermarket uppers offer several benefits over using the stock ones, albeit at a higher cost. The F body spindles are about 1.5" longer than the stockers. This is a problem because it gives you too much negative camber with stock shim packs. This can be overcome by stacking about an inch worth of shims between the frame and the control arm shaft, which might cause clearance problems with headers. The tubular control arms are made shorter, to fix this problem, and also they are set up to give you more caster, to help with high speed stability. They can also be set up with almost neutral alignment, (make sure you use the tubular upper's manufacturers alignment specs!) which will give your car a more modern handling feel.  They also lower the front end about 1.5" or so, which also helps handling. In the '60's, the cars were engineered to understeer, the idea being that it would be better to have the car plow through a turn than to have the rear come unglued and result in a 360. Cars in the '70's handled pretty good, a lot better than their '60's counterparts. Much of this was due to revised front end alignment angles, stiffer springs and better tires. The second generation F bodies were the first (I believe) to have revised front end geometry, and they handle pretty well, even by today's standards! 

Another advantage to the aftermarket uppers is that it is possible to put 12" rotors on your car. In order to use the big rotors, you need to get B body (big car) spindles from a car that has 12" rotors. B bodies were available with 11" or 12" rotors, so be sure to measure them before going crazy in the salvage yard! You also need big calipers and rotors with the right bolt pattern for A bodies (the big cars use 5" on 5" bolt pattern, the A bodies use 4 3/4" on 5" bolt pattern). The '88-'92 1 LE Firebird/Camaro rotors are perfect size but have metric studs. You can either get the metric nuts for them, or just press out the metrics and install SAE studs. Calipers from a mid '80's B body with 12" brakes are needed.

Front end during assembly.

The biggest problem with using F body spindles in an A body are the ball joints. I am not sure about the upper ball joint (I used Hotchkis uppers and they came with the ball joint installed), but there are no off the shelf ball joints that will couple the A body lower control arm to an F body spindle! The taper/length of the stock A body ball joint won't match the F body spindle and the F body ball joint's body is too large in diameter to fit the A body's lower control arm! The solution is actually pretty simple. Use the F body ball joint (Moog # K6145 or equiv.) and have a machine shop turn it to fit (2.010", to be exact!). A local machine shop charged me $35.00 to turn my ball joints and press them in for me. H.O. Racing used to sell the lower ball joints already modified, but I am not sure if they are still available. I have also heard that Global West has them!

The outer tie rod ends are also different. '64-'70 vehicles use Moog # ES-2033RL and '71-'72 use Moog # ES-427R, to mate with the F body spindles.

Once the spindles are all in and all of the plumbing hooked up, the rest of the brake parts are straight F body parts.

My rear brakes are rebuilt with new stock parts, except for the drums, which are used aluminum drums from an '80's vintage F or G body.

Aluminum rear drums, note lack of rust!

To further improve handling, heavier duty springs, good shocks, polygraphite bushings and sway bars are all good ways to eliminate dragging the door handles in tight turns with your A body!

Front swaybar & steering parts.

I used a 1.25" sway bar from a '78 TA, with new Polygraphite bushings and end links up front, and a N.O.S. 7/8" GM sway bar (also obtained from Butler Classics) out back with homemade boxed lower control arms. I used inserts from Butler Classics and welded them into my stock lower control arms. After drilling 4 holes, the stock bar bolted right in.

The control arm bushings I used are all Energy Suspension polygraphite, as are the body bushings.

The springs are stock '66 A/C springs in front, and '67 wagon springs in back. I used the '67 wagon springs in back due to the '71 vintage 8.5" rear, the spring pads are a bit lower on the later rears.

To complement the handling mods, I have installed an '85 Monte Carlo S/S steering box in my car. This is not the bolt in that everyone thinks it is, but it is not too difficult to make work. The advantage to this box is that it has the same internal stops as the '64 to '72 A bodies (unlike the F body boxes, which severely limit your turn radius in an A body!). The disadvantage is that it uses metric, aircon type fittings for the pressure and return hoses. The rag joint is a problem too. You must use the pitman arm from an A body power steering box. The one on the Monte box is way too big! A manual pitman arm is not interchangeable with the power one. I ended up buying an entire power steering setup from a '70 GTO just to get the pitman arm. I also got the box, brackets (which I needed anyway, since my car was non power ANYTHING) pulleys bolts etc.  Don't try to pull the pitman arm from a box without the proper puller. They are a real bear to get off! I bought a $19 puller from Harbor Freight that worked real well! After removing the BIG (!) nut I doused the shaft with liquid wrench for about 2 weeks. Then I attached the puller to the assembly, tightened the bolt, and it popped right off!!!! Installation is reverse.

'80's vintage S/S Monte Carlo steering gear.

The return hose is easy, just make sure that you take the old hose when you get the box. Cut the old hose off the metal fitting and put the metal fitting in your stock hose and secure it with a hose clamp. The pump end attaches directly to the pump, so that is all there is to this mod.

The pressure hose is a bit more involved, and requires a trip to a store or shop that can swage hydraulic hoses. You  can buy 2 hoses, one metric and one SAE and have the store cut them in half, then connect the S.A.E. pump end to the metric box end with a sleeve. Not too pretty but it works! 

OR............

You can get a pressure hose from an '85 Olds Cutlass Supreme with the 307 engine and either change the fitting on the end of the hose to an SAE one, or change the original pump fitting and pressure regulator to a metric one from a mid '80's rear wheel drive GM car and use the hose as is!

The rag joint from a '79 to '84 GM full size truck will bolt right up!

Picture and parts list below courtesy of Stan at Skullmobile.com!

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