Right-front brake slightly dragging

[MopaR&D]

My '70 Duster has the Dr. Diff front disc brake kit (11.75" rotors) but this issue also existed with the '73-up A-body front discs I had before that; I think it may have contributed to the caliper on that same side eventually locking up and overheating.

I've had a persistent and annoying issue where the front passenger side brakes seem to very slightly drag. There's a light but very audible squeaking while driving coming from the front right side that goes away as soon as I touch the brake pedal. It also looks like there's more brake dust buildup on that side vs the front left. What could be some potential causes of this?

 

[Bewy]

A bent mounting might be causing the pad to drag. Since it has done it with two different cailpers, it is unlikely to be the cal, pistons etc. Might be a partial blockage [ sediment/rust ] in that line or hose.

 

[Kendog 170]

A collapsed flexible brake line can act as a check valve (collapsed inside the hose) and make a caliper drag. I also once installed a 1974 disc set up and had to add a shim between the mc and firewall because both sides were dragging. I loosened the mc bolts enough to diagnosed that that was the issue. I didn't realize there's a gasket. Just spit balling here.

 

[George Jets]

Yeah the D100 Trucks have that problem with the caliper piston hanging up over time.

Have had to replace the caliper when that happens.

Would have liked to cook the grease out of the left front '78 D100 that I had. Had to stop and let it cool down and try and work it back.

Changed the one caliper when I got back in.


☆☆☆☆☆

 

[MopaR&D]

A collapsed flexible brake line can act as a check valve (collapsed inside the hose) and make a caliper drag. I also once installed a 1974 disc set up and had to add a shim between the mc and firewall because both sides were dragging. I loosened the mc bolts enough to diagnosed that that was the issue. I didn't realize there's a gasket. Just spit balling here.
View attachment 1716440972

This might be something, I did replace the MC years ago and I don't recall if I put a gasket in there; kinda hard to tell from the pic but is that gasket compressible (foam) or a harder material?

I won't rule it out but I doubt it's the soft line as I replaced those with SS lines that I optioned with the Dr. Diff kit.

 

[Inertia]

Hubcaps/wheelcovers ?
If so. Remove and test .

 

[MopaR&D]

Hubcaps/wheelcovers ?
If so. Remove and test .

Nope, running 18" aluminum late-model Mustang wheels, lots of airflow. It's the car in my avatar. Good suggestion though.

 

[Kendog 170]

kinda hard to tell from the pic but is that gasket compressible (foam) or a harder material?

I didn't not know at the time so I made one out of aluminiun. Later I saw in pic the plastic one that comes with a new one. just loosen the 4 mounting bolts a little and see if it relaeases. If not no harm done.

 

[MopaR&D]

Got around to checking some things out today. I looked at the return of the piston in the master cylinder, there is no gasket/spacer but the piston does fully return rearward when the brake pedal is released. I pulled the wheel off the passenger side and took off the caliper, no strange or uneven wear on the pads. The calipers and brackets from the kit are powdercoated so I grabbed a sharp scraper and removed the coating from the ways to make sure they were smooth and applied some silicone high-temp brake grease then put it back together (already did it on the driver side on first install but got a bit lazy when I first installed the pass side). I also very lightly snugged up the wheel bearing on the pass side, had a tiny bit of play which I thought might be contributing. Afterwards I went on a short drive and it seemed to be a bit better, no squealing but I don't think I drove it long enough to get everything fully heated up. We'll see if the issue comes back.

It does mess with my head, sometimes the car pulls to the right a bit when applying the brakes but it does have very wide low-profile front tires (255/40R18) and I'm running 7° of caster and -2° camber so it might just be following the crown of the road?