I Just Installed A Four Wheel Power Disc Conversion On My 69 With All New Stuff. The Front Calipers Are Very Tight On The Rotors, I Can Barely Turn Them By Hand After The Pedal Is Released. I Have Checked Pedal Travel And Freeplay Is Good, I Disassembeled The Calipers And Even Installed New Seals, Tried Opening The Bleeder Screw To Release Pressure, Removed Some Fluid From The Master Cylinder Also. I Can Push The Piston Back And It's Fine Until I Hit The Pedal Once And They Are Tight Again. Any Ideas Left?

Had this problem on a 68 Z/28 and in my case in turned out to be the master cylinder was bad. For some reason it happened after calipers were rebuilt.
Good luck.

Thanks For The Reply, I Have Had Three Different New Master Cylinders On (for Other Reasons) And This Problem Will Not Go Away It Has Been Tight Ever Since I Put Them On. I Even Took Out The Banjo Bolt From The Line And Cut It Off Some Because I Was Told It Might Be Hitting The Piston But I Can Push Back The Piston By Hand So That Was Not The Problem Either. I ALSO LOOSENED THE MASTER CYLINDER FROM THE BOOSTER TO MAKE SURE THE ROD WAS NOT TO LONG AND THEY WERE STILL TIGHT, Thanks.

on a van i have i was told that the line to the caliper was bad, when the brake was applied the hose would callapse and not release the caliper

I Am Using Braided Stainless Lines And Both Are New And Both Sides Are Tight. Thanks

What master cylinder are you using? Is it the rear calipers only doing this, or all four. Drum brake calipers have check valves in both of the outlet connections that will hold fluid pressure in the lines. Disc brake calipers have one in the rear lines only, and it needs to be removed to run discs in the rear.

I was just gonna say what Mark did.

Take a sharp fine thread "deck screw" and carefully screw it in the M/C side port seats holes and GENTLY pull them out and remove any check valve stuff that are behind them.

Then very carefully reinstall the seats. And you should be good to go..

My big rebuilt M/C didn't have anything back in there..

pdq67

Only The Front Calipers Are Tight The Rear Is Fine. I Had A Hard Time Bleeding The Rear But They Seem Ok Now. I Have A New Deep Rod Master Cylinder With A Combination Valve Under The Master Cylinder. This Is The Master Cylinder I Received With The Conversion Kit. IS THERE A CHECK VALVE IN ALL THE MASTER CYLINDERS OR JUST SOME OF THEM? Thanks

Just some. Probably none with a conversion kit master.

You never said whether it released when you opened the bleeder.
Given the info you did provide...

If you open the bleeder and the caliper does NOT release, the problem could be in the caliper slides having improper lubrication or bent/binding, not as likely to be a hydraulic problem.

If you open the bleeder and the caliper DOES release, it could be a restriction or residual valve.

If you open one bleeder, and both calipers release, it's likely to be a residual valve in the master or restriction before the lines split.
If only that one caliper releases, it is more likely a restriction in that side somewhere after the split.

Crack the line at the master cyl and see if that releases the caliper.
If it does, then you know it's the master cyl.

Remove the brass seat in the master cyl by screwing in a screw, pull it with a claw hammer on the screw. I'd first probe the hole in the brass insert. Normally the hole should go all the way to the MC bore. If you hit something just behind the seat, that's the residual pressure valve, it's rubber the size of a pencil eraser. Rear port of MC goes to rear brakes, front to front, disc master cyls have larger reservoirs than drum master cyls.

I Have Tried Opening Both Bleeders And There Is No Change On Either Side. It's Strange That Both Sides Are Tight And Doesn't Seem Likely Both New Calipers Would Be Bad. Like I Said I Took Both Of Them Apart And Put In New Seals And The Pistons Looked Great But No Change. I Just Put It Back Together And Drove It Around The Block And The Front Was Warm But It Didn't Seem Real Hot But I Didn't Go That Far Either. Thanks For All The Inputs.

Did you lubricate the slides with break caliper lube?

I thought cracking a bleeder helped, it if didn't, then it's just caliper drag due to friction between the caliper bracket guides and the caliper. There can also be problems if the caliper is mounted a bit too far inboard, the outer pad will rub or you can have problems getting the caliper to slip over the rotor. The caliper is limited in how far outboard it can go, will can travel inboard as the outer pad wears.