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Discussion Starter #1
Hi All,

Last summer, I did a front end job on my '81 Bronco.

New pads, calipers, disks, wheel bearings / races, booster, and master cylinder.

However, lately I discovered that my front brakes are dragging.
When I jack it up and spin the tire, there isn't any free rotation. They take some effort to get moving and then just stop instantly after I let go. I took the tire off, I could barely turn the rotors by hand. But, once I remove the brake caliper, they spin nice and free. This is the same on both sides.

There doesn't appear to be any uneven wear on the pads and the piston in the calipers seem to move well. Also, just to check, I unbolted the master cylinder from the booster to see if somehow it was constantly putting a little pressure on it, and there was no difference.

Any ideas? I'm not particularly sure what to do about this, and it's taking a hit on my performance, not to mention my gas mileage. Don't know what to look into next.

Thanks.
 

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Ford Hoarder
78 & 92
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Check the flex lines, crack open the fitting the holds them to the caliper and see if the caliper releases. Old lines can sometimes swell and act like a check valve.
If it doesn't release maybe the calipers are stuck or the master cylinder is bad, but usually those leak fluid not hold it
 

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Do the slide pins move freely? Ive come across quite a few that were seized up.
 

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Super Moderator
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Discussion Starter #5
Check the flex lines, crack open the fitting the holds them to the caliper and see if the caliper releases. Old lines can sometimes swell and act like a check valve.
If it doesn't release maybe the calipers are stuck or the master cylinder is bad, but usually those leak fluid not hold it
Thanks for the idea. I'll give this a try and see what it does.
I've replaced the flex lines, but it's been about 10 years.

pfun41 said:
Do the slide pins move freely? Ive come across quite a few that were seized up.
The '81 doesn't have slide pins. I'm not sure what year they added those. Thanks though.
edit: Looks like '93 or '94 was the first year for that design.
 

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It is normal for the pads to drag on the disks some after a stop. The pads will back off when running as the bearing run out will push the pads back when you turn the truck. You can push the pads back by jacking up the tire and kicking the sidewall on the front and back of the tire. There is really nothing to cause the pads to retract. Some vehicles say the shape of their seal on the caliper piston is supposed to retract the pad, but I have one of those vehicles and it does not work as advertized.
 

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Roller rockers are gay
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It is normal for the pads to drag on the disks some after a stop. The pads will back off when running as the bearing run out will push the pads back when you turn the truck. You can push the pads back by jacking up the tire and kicking the sidewall on the front and back of the tire. There is really nothing to cause the pads to retract. Some vehicles say the shape of their seal on the caliper piston is supposed to retract the pad, but I have one of those vehicles and it does not work as advertized.
Maybe so, you are correct. However when one has to force the wheel to turn with no vehicle weight on it and it stops the instant he lets go there is a problem. I have never ever had a properly lubed/working caliper do that. Only ones that were locked up.
 

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Discussion Starter #9
Yeah, I noticed that the sliding surface was bone dry. (On these, the whole caliper just slides back and forth along the bracket that holds it to the wheel). I put some grease on that surface to lubricate it. I'm sure it's beneficial, but it didn't resolve the issue.

However, I did open up the bleeder valves and forced the caliper back further (they slide very easily, so I don't believe there's an issue there). Once I did, the tires spun much more freely. I did this on both sides.

After that, I pumped the brakes a few times and then tried spinning them again. The driver's side still spun rather well, but the passenger side was locked up again.
Makes me think that something further up the line than the caliper is not letting fluid properly back out.

I'll follow your advice about removing the lines from the calipers and then the master cylinder, and seeing if it makes a difference.

If it turns out to be the flex hoses, I'll probably go with a braided steel replacement this time.
 

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Discussion Starter #10
What KIND of grease? Common chassis grease will turn to a sticky varnish from the heat there, CAUSING the caliper to stick. Use only "brake grease" as shown in that link.
I have some chassis grease to clean off....

That's backward; with the brakes sticking, start at the MC.
Okay, will do. It's easier that way anyway.

They're not worth it. The braiding is just for exterior abrasion, and that's not your problem. In my life, I've never seen a caliper hose worn through in a way that braiding would have prevented (or even slowed). Those expensive braided hoses still have the exact same (or cheaper) rubber hose inside, and it can still degrade inside or leak from the poor swaging that the braiding sometimes causes. Use the highest-quality standard rubber hoses that you can find.
I thought they were simply an upgrade all around. Not necessarily just for abrasion (I've off-roaded mine for 10 years and have never had anything touch the brake hoses. If something was up that high to get to them, I'm really driving somewhere I shouldn't be), but also for better braking. For the most part, I hear they simply don't flex as much, so they give a stiffer brake pedal.
Good to know they're still rubber on the inside that can wear out.

I was looking at these from JBG: http://shop.broncograveyard.com/Sta...e-Brake-Lines-Pair-1980-89/productinfo/32558/


If they're not worth it, I'm fine with saving $50.
 

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Discussion Starter #11
Alright, well, I tracked the issue down.

It looks like the calipers simply aren't sliding correctly. After they release, if I use a large screwdriver/prybar to slide them one way or another, I can take the pressure off both pads and the wheel will spin freely.

So, looks like I just need to figure out why the caliper itself isn't sliding back to center. Doesn't seem to be anything with the fluid or the caliper piston. Just the caliper itself sliding back and forth on the hub.

For starters, I'll just try cleaning it all up, using a wheel brush to get it all smooth, and putting some proper brake grease on them. If anyone has any other ideas too, I'm open.

Thanks all.
 
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