This is how I installed 12” “hubless” rotors and dual piston calipers on the front. I wanted the hubless rotor so that when it is time to replace the rotor I don’t have to change the bearings that are in the stock disc brake rotors. The diameter is bigger for better stopping and the dual piston calipers work better and look awesome through the wheels.
There are 2 types of factory front lower control arms; those with round rear bushings and those with oval. GM pretty much mixed and matched these at random. The round ones were the first design then the oval ones came about to give a little more shock absorption from pot holes and such. The round ones give you stiffer suspension, which is fine if you leave the round rear bushing rubber. But if you plan on driving on the street and want to use urethane bushings, I strongly recommend using the control arms with the oval bushings. The extra material in the oval bushings offset the stiffer urethane, resulting in a stiffer response suspension yet forgiving with shock from the road.
Catastrophic control arm failure
Once I selected the lower control arms I wanted, I welded in some reinforcements. These arms are known to crack and brake because of 30 years of fatigue.
I have put a kit together for the mod. I plasma cut, out of 1/8” steel, the plates to be welded in. After the plates are in the 1” x 1/8” steel strips are welded. Notice the clearance hole for the sway bar mount. After the welding was finished, I had the arms galvanized and painted.
I chose the BOP (Buick, Oldsmobile, Pontiac) upper control arm cross shafts because they use a bug nut on the ends rather than screws. I have had the Chevelle ones loosen and slip out a bushing! I pressed Polyurethane bushings into the upper control arm with the shafts.
It is very important to get one bushing in first then put the other bushing over the shaft and put the shaft in the control arm, and then finish pressing the second bushing into the control arm or else you will not get the shaft in.
Install the springs but be sure not to pinch the battery cable mentioned above. I used spring compressors that fit inside of the spring. I had to drill out the hole that the upper shock mounts through to get the spring compressor rod through. Again, wish I knew that before galvanizing the frame! This was due to the galvanized coating and primer and paint build up in my case. Once the spring is compressed, I connected the upper and lower ball joints to the spindle and torqued the nuts down.
Note: The Front upper ball joint mounting screws get torqued to--------10 lb-ft
Then release the spring compressor and remove through the bottom holes. The springs I am using have a resting height of 15” and .635” coil diameter. I am leaving off my front shocks and sway-bar until I know these springs will give me the desired ride height. To change out the springs I would need to remove the shocks and 1.25” diameter sway bar so I will just see where it sits after the body has settled on it after a week or so. It is highly unlikely that I guessed on the correct spring since each situation is unique. This Chevelle has a chopped roof, no AC, battery relocated, LS motor with turbo, aluminum radiator, cowl hood, side pipes etc. All these things affect the ride height so I will just have to see.