Locked up Front Discs

[quapman]

I installed a new pair of front calipers on my 73 Challenger recently. Today, I finally got around to bleeding them. Once bled and the bleeders closed, I pumped up the pedal, which was pretty spongy, but it came up nice & firm.

Now, my front rotors are locked up.

The "BRAKE" light in the dash is on and was on prior to the caliper swap.

Everything is stock....manual front discs and 10" rear drums.

What's my major defect?

[Bullitt-]

I've read that if the push rod is to long this can happen.... As for the light being on after bleeding the system stomp the pedal hard once to reset the switch..also the parking brake turns on the same light & may be the culprit.

[72rtchallenger]

I've read that if the push rod is to long this can happen.... As for the light being on after bleeding the system stomp the pedal hard once to reset the switch..also the parking brake turns on the same light & may be the culprit.

[quapman]

Already checked the parking brake switch, nope.

Everything is factory original, so I doubt the pushrod.

I'm suspectiong the combination valve, but have never had one go bad before. I suppose a 40 year old part could easily fail.

[Chryco Psycho]

the piston may not sit at the same depth in the rear of the master so I would check that again

[quapman]

Would not have believed it unless I tried it, but I stomped the pedal and the light went bye-bye.

I cracked one of the front lines to the valve and let out a little fluid. Both calipers loosened up. They got tight again after the super-stomp.

Thinking maybe everything is actually OK, but I think I'll need a trip around the block to be sure. Still wondering about the combo valve in the back of my head.....

[Bullitt-]

Would not have believed it unless I tried it, but I stomped the pedal and the light went bye-bye.

I told you that rooster dips snuff  ... Now pull the MC & adjust the push rod shorter . 

[mcmasad]

Quick question as I am having a similar issue.  I've pulled off the MC and see the rod that needs to be adjusted, but how do you adjust it?  Does it pull out?  I lightly pulled on it hoping it would come out and I could mess with it, but it gets hung up and I don't want to ruin anything by tearing it out.  It looks like I should be able to adjust the tip of the rod since it appears there are threads (although maybe a quarter inch of threads), but I can't get it to move.  Thanks in advance for any advice

[Bullitt-]

I've never had to make the adjustment & am only aware of it through reading on the internet.
I just reviewed my service manual & it says nothing about adjusting the length, I assume that you just turn the nut on the end that goes into the MC.

[quapman]

Will be swapping my M/C in a few days. Will advise as to how the rod is retained and adjusted.

I removed my brake light switch, pulled back on the pedal and have no change.

My newest theory is that one circuit of the master is blowing by and causing unequal pressure in the combo valve.

[mcmasad]

Thanks.  I checked the service manual and couldn't find anything either.  I think the nut on the end of the shaft should move, but mine seems to be stuck.

[quapman]

As I suspected, the rod in a MANUAL setup is NOT adjustable, so please go back to the fountain of misinformation and spit that info back in. 

There is also no retainer, other than a very tough rubber sleeve (like a really long o-ring) that locks the shaft into the piston. Needed vise-grips and a prybar to get it out.

My blow-by theory held water. New master is in and bled. Good, firm pedal, no locking. I need to stop trusting 30 year old parts.

[Bullitt-]

Glad you figured correctly & all your problems are solved...  ...maybe it's the 43-yr old part ya need to worry about 

[brads70]

As I suspected, the rod in a MANUAL setup is NOT adjustable, so please go back to the fountain of misinformation and spit that info back in. 

There is also no retainer, other than a very tough rubber sleeve (like a really long o-ring) that locks the shaft into the piston. Needed vise-grips and a prybar to get it out.

My blow-by theory held water. New master is in and bled. Good, firm pedal, no locking. I need to stop trusting 30 year old parts.

Yep mine is exactly the same setup!

[quapman]

Glad you figured correctly & all your problems are solved...  ...maybe it's the 43-yr old part ya need to worry about 

I forgot to mention that my tinfoil helmet fell off while changing the combo valve. I believe THAT is where things went south.....