Right front caliper hangs up

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DusterDaddy

DusterDaddy

sledgehammer mechanic
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74 Duster with factory front disc brakes.
All new lines and hoses. New booster and master cylinder. The only part not replaced is the proportioning valve.

Overall the brakes don't feel right, although I have to admit its been 38 years since I drove a 43 year old car with power brakes. They feel like an unusual amount of effort on the pedal is needed.

I have only done short test drives with the car in the neighborhood since my kickdown linkage isn't installed on the carb side yet.

On 2 of 3 trips, the right front brake stays applied. Not enough to keep the car from moving but enough to make even a clueless driver know it's happening.

The caliper released itself after the car sat for a while the last time it happened. It happened again yesterday and I will see if it has released itself today when I get home from work.

Why might this be happening? All components are new or remanufactured.
 
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I would look at the caliper slides first, make sue they are lubed well and caliper moves freely on them. Next would be to see if it is the caliper piston freezing in the bore, or if the hose is collapsing internally. When the caliper is hanging up, jack up that wheel, and while spinning the wheel, if you can, first wiggle the brake hose to see if it frees up at all. If it does, the hose is collapsing. Next would be to loosen the bleeder screw and if that works, it is probably the hose. Look to see if the rotor and caliper are bluing, and if the caliper piston dust seal is burning/ cracking. If the releasing of fluid pressure from cracking the bleeder did not work, it is definitely the caliper.
 
Whether new or not, if that brake is made in China, try like hell to find a different one.
 
since hoses are new it's unlikely that is the problem, unless the line or hose is kinked. But you did say it was a new m. cyl and booster. Could be wrong pushrod or incompatible parts in that area. Or it could just be a defective caliper.

There was a thread recently (last month or so) about an engine swap and the heat from engine and exhaust were overheating proportioning valve, making it apply the brakes, IIRC.
 
jos51700 said:
Whether new or not, if that brake is made in China, try like hell to find a different one.
Click to expand...

There are no new, made in the USA components for the factory brakes that I'm aware of. New calipers and pistons are all made overseas and have been for some time regardless of brand. Same for the hoses unless you go steel braided, there may be a few of those that are made here but not all of them are for sure. Everything else will be re-manufactured stuff, and there's no guarantee that will be better regardless of where it was originally made, that'll depend on the rebuild and they're not all great.

Just have to check the pistons in the bores before you mount up the calipers and take/send them back if they aren't right, regardless of them being new or re-manufactured.

For the OP, sounds like the hose to me. Doesn't matter if it's new or not, brand new hoses sometimes come with defects and some people like to clamp hoses with vice-grips to change calipers and that can total a hose with one shot. It could also be a damaged hard line, so take a look at the metal lines too. A crimp in the line could act like that as well. The brake releasing after it sits for awhile suggests that the fluid is leaking back to the m/c over time, that sounds exactly like some kind of hose restriction. The piston hanging up is less likely to resolve on its own while sitting.

If it were a master cylinder or booster issue it wouldn't just be one wheel. There could be multiple issues of course, but the caliper hanging on one wheel isn't likely to be a m/c. If it were both fronts that's a different story.
 
rustycowll69 said:
since hoses are new it's unlikely that is the problem, unless the line or hose is kinked. But you did say it was a new m. cyl and booster. Could be wrong pushrod or incompatible parts in that area.

There was a thread recently (last month or so) about an engine swap and the heat from engine and exhaust were overheating proportioning valve, making it apply the brakes, IIRC.
Click to expand...
I have seen plenty of new brake hoses collapse internally, so don't discount this. Start at the area of the dragging and eliminate from there
 
And no it should not be hard to press-the pedal- usually very easy with power brakes
 
I will check out the caliper and hose.
when the new booster and master cylinder arrived it was assembled as a unit. I did remove the master cylinder so the booster could be painted. I ran the car a half dozen times with the rod hanging out of the booster. I hope I got it right when I reassembled it.
 
DusterDaddy said:
I will check out the caliper and hose.
when the new booster and master cylinder arrived it was assembled as a unit. I did remove the master cylinder so the booster could be painted. I ran the car a half dozen times with the rod hanging out of the booster. I hope I got it right when I reassembled it.
Click to expand...
I believe the end of the pushrod fits into a 'square cut ' o-ring in the back of the master cylinder piston, which grabs and holds the end of the pushrod, when FULLY inserted.
 
72bluNblu said:
There are no new, made in the USA components for the factory brakes that I'm aware of. New calipers and pistons are all made overseas and have been for some time regardless of brand. Same for the hoses unless you go steel braided, there may be a few of those that are made here but not all of them are for sure. Everything else will be re-manufactured stuff, and there's no guarantee that will be better regardless of where it was originally made, that'll depend on the rebuild and they're not all great.

Just have to check the pistons in the bores before you mount up the calipers and take/send them back if they aren't right, regardless of them being new or re-manufactured.

For the OP, sounds like the hose to me. Doesn't matter if it's new or not, brand new hoses sometimes come with defects and some people like to clamp hoses with vice-grips to change calipers and that can total a hose with one shot. It could also be a damaged hard line, so take a look at the metal lines too. A crimp in the line could act like that as well. The brake releasing after it sits for awhile suggests that the fluid is leaking back to the m/c over time, that sounds exactly like some kind of hose restriction. The piston hanging up is less likely to resolve on its own while sitting.

If it were a master cylinder or booster issue it wouldn't just be one wheel. There could be multiple issues of course, but the caliper hanging on one wheel isn't likely to be a m/c. If it were both fronts that's a different story.
Click to expand...

That's why I said find a different one, not my normal Made In USA suggestion
 
If its the hose collapsing, then i'd recommend steel braded brake hoses. Some states wont allow them i think because they are not DOT certified. However they are superior to rubber hoses. If your state doesnt allow them, i'd slide black shrink tubing over the steel brade to hide it and run em anyways.
 
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