Have been concentrating on improving my brakes and have a slight problem.

I have a '72 and did the Toyota front caliper brake switch a few years ago and never really found the switch to improve all that much. Within the last month have switched to stainless steel brake lines and changed out the brake vac. Both sets of parts came from MSA. I have bleed the brake lines two times since with Dot 4 brake fluid. The rears are stock.

Now the problem is that before the master vac switch I had only moderate brakes and now although the braking is improved, when I apply the brakes I have the front right tire locking up and the car pulls to the right. Other three tires don't lock up. Any suggestions? Thanks.

Do you feel a vibration when you brake, like if the rotor was "warped?" That is a sign that you have a spot where the brake pad material is more or less heavily deposited and it grabs a little more or less. About the only solution for that is to turn or sand the rotor face.

No shake at all, in fact I had the rotors turned recently. Could it be a stuck rotor? Is there some type of proportioning device that give equal pressure to all 4 brakes that may be out of balance?

Firstly, with the Toyota switch the braking should have improved significantly so I suspect there was something not right with your calipers in the first instance. Were they new? If your brakes are pulling badly to one side then it's usually a problem with caliper pistons sticking, probably from when you first put them on.

I'm sure the calipers were rebuilt since I needed to give them my old ones as a core. They were purchased from Advance Auto.

there have been occasions where rebuilt calipers from local auto stores stick. check it our, they will replace under warranty.