1972 Polara passenger side front disc lockup and smoking

[72polarbear]

Currently falling through a rabbit hole trying to diagnose why the passenger side front brake was smoking after a drive home. At first I realized that the eBay rotors I bought were rubbing and grinding itself against the ring around the spindle so after ordering the proper ones from oreilys and installing them it still smoked up. However only the passenger side is the only one with this problem even with the eBay rotors the driver side works fine. This leads me to the caliper being the problem so I sanded down and greased the spots were the pads slide against aswell as the pins since the rust didn’t let the pins slide freely. After all this the pad rotor still gets stuck. Now I’ve opened the bleeder nipple just enough for the caliper to get loose enough to spin somewhat freely. Would it be safe to assume that the caliper is bad?

 

[Big_John]

More likely the brake hose is bad.

What happens is the hose gets damaged internally from improper handling (like letting the calipers hang) or they fail internally from age. It will open up under pressure and then close when not under pressure, making kind of a one way valve.

 

[rags]

Now I’ve opened the bleeder nipple just enough for the caliper to get loose

More likely the brake hose is bad.

opening the bleeder relieves the pressure retained in the caliper by the bad hose.

 

[Big_John]

opening the bleeder relieves the pressure retained in the caliper by the bad hose.

Exactly!

 

[rkrochen]

I have seen this caused by both a bad hose or seizing calipers. Back in the day it was very common for a caliper to seize. Also make sure the caliper is free to slide on the pins. These can also seize up and need to be cleaned and lubed.

 

[carguy300]

On my 68 that disc conversion done, my left front would not fully release. New calipers and hoses, same issue. Found perportioning valve that split the 2 front wheels. I replaced it with a compression tee and that ended that problem.

 

[Boydsdodge]

I am seeing something other than brakes seized. On one of my 72 Polaras I had the problem of the replacement rotor rubbing grinding the spindle from the new rotor bearings being different size. This was way back in the 80s, but I had to put turned wrecking yard rotors on. 72 is a change year for front brakes. Maybe your spindle was changed to a later spindle. do you have your old bearings and rotor to measure and compare.

 

['66 Fury I]

I have seen this caused by both a bad hose or seizing calipers. Back in the day it was very common for a caliper to seize. Also make sure the caliper is free to slide on the pins. These can also seize up and need to be cleaned and lubed.

Compression fittings are not approved or safe in brake systems. The systen can fail under high pressure, like a panic stop. double flare is the way to go. Lindsay

 

[rkrochen]

Compression fittings are not approved or safe in brake systems. The systen can fail under high pressure, like a panic stop. double flare is the way to go. Lindsay

I think you meant to direct this to carguy300. Totally agree with you that a double flare is what is needed.

 

[carguy300]

Thats what was talking about.

 

[carguy300]

Flare tee, used same brake line fittings.

 

[fury fan]

Late to the party, came here from @72polarbear 's newer thread on calipers.

With some rotors being mis-applied (73 rotors being sold as 69-72 units) it is possible you got a 73 rotor on your 72 spindle.
It will seem to fit OK, but will have a little bit of rocking due to the inner bearing being larger on the 73 rotor.
this will allow the rotor to be out of plane from the brake pads, and perhaps cause to drag on the edges.
I would be surprised that the bearings wouldn't self-destruct in short order, though. And the seal is different, so not sure how well that would install.

Just something to check.

Strange things could occur if 1 rotor was wrong, or if 1 spindle was changed years ago to the other version. Which looks exactly the same except for the inner diameter for bearing and seal.

 

[rags]

if 1 spindle was changed years ago to the other version.

i've seen hack repairs done on repairable auction cars that involved junk yard suspension assemblies complete with brakes.

 

[Boydsdodge]

I remember (kinda) back at the dealer a tech installed one piece rotors on a 72 polara and when he moved it out of the shop it was scraping the back side. Are 72s a two piece rotor. Too tired to get up and look in my parts book.
OK, I got off my *** and had a look. Pic shows what I found. Just what I thought.

 

[fury fan]

Yeah, seems 72 was a changeover year, maybe on rotor construction style, maybe on the inner bearing/seal also.

The 1-piece/2-piece distinction has gone away in the last batch of years in the aftermarket, both 69-72 and 73 (and newer for 1/2-ton trucks) are 1-piece castings.
The only difference (I believe) is the machining at the inner bearing race and seal. That's the difference in associated parts, anyway. So would make economic sense to use the same casting cores.