Brakes rubbing on new disc brake system

21BaylinerCC

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I recently installed a Tie Down 12" vented rotor kit (including actuator) on my Escort Trailer. After bleeding the system, I took the trailer for a test drive. I noticed that the passenger side brakes are rubbing the rotor, while the driver side seem fine. Any thoughts?

FYI - the kit is called "12" Vented Disc Brake S.A. Complete kit, 6 lug #82406"
 

dingbat

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Probably air in the line
Unlike drums that use springs to retract the pads, disc use the push-pull of the actuator cylinder to extend and retract the cylinder.
 

smokeonthewater

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Actually there IS no pull to retract the pads.... Air in the system wouldn't cause this either... The pressure in both calipers will be the same..
Check wheel bearing adjustment.
 

dingbat

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Actually there IS no pull to retract the pads.... Air in the system wouldn't cause this either... The pressure in both calipers will be the same..
Check wheel bearing adjustment.
Suggest you go back and retake hydraulics 101 then get back to us
 
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gm280

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Being how there are zero springs and such to retract the caliper pistons on disk brakes, the master cylinder with the foot petal retracting is the only thing to pull the pistons back a little from the rotor. So the disk pads hover very close to the rotors all the time. So if the rotor is warped or any endplay in wheel bearings, it is possible to drag... JMHO!
 

Lou C

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Did this trailer originally have drum brakes?
If so the actuator has to be modified (remove the check valve) or else the disc brakes will not release all the way..
Disc brakes depend on the square faced seal in the caliper to force the piston back in the relaxed position but you must also have no residual pressure in the actuator as well; fluid must be able to freely flow back.
I prefer drum brakes in a surge system because of the strong return springs. Once I learned how to water proof the wheel cylinders they have worked very well.
 
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Idlespeedonly

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Did this trailer originally have drum brakes?
If so the actuator has to be modified (remove the check valve) or else the disc brakes will not release all the way..
Disc brakes depend on the square faced seal in the caliper to force the piston back in the relaxed position but you must also have no residual pressure in the actuator as well; fluid must be able to freely flow back.
I prefer drum brakes in a surge system because of the strong return springs. Once I learned how to water proof the wheel cylinders they have worked very well.
He said he put on a new actuator.

Nothing pulls,sucks, or pushes the piston back in on a caliper.
You said they are rubbing the rotor, if you jack up the wheels is there any drag?
It is possible you may have a sticking caliper.
From what I have heard tie-down isnt the best available.
 

smokeonthewater

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There is actually some debate on the topic.... Way back when disc brakes were new GM claimed that their square cut seal would deform slightly upon application of the brakes and cause the piston to retract slightly upon release...

Of course we are talking about a couple thousandths of an inch here and that isn't enough to get the pads off of the rotor... Next is the runout of the wheel bearing. Some feel that will release the brakes a bit and others feel that will only move the caliper on it's slide pins.... Next is contraction of the brake pad material as it cools after a brake application... Next theory is that at highway speed there is a boundary layer of air on the rotor keeping the pads off of it without significant application force.... Finally, many claim that the pads are supposed to very lightly drag on the rotors and the resultant drag is negligible.... The further they are from the rotors the more fluid volume is required to apply them.... Some people say that when disc brakes first came out NASCAR teams were slow to start using them because the drag of the discs caused the drum brake cars to top out slightly higher...

The truth is likely a combination of all of the above.....

Again as I said before check for slop in your wheel bearings....

It may turn out that the one with some drag is normal and the other has a loose bearing.

Hearing and or feeling SOME drag is a non issue... If you can't easily spin the wheel by hand it IS an issue.
 
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gm280

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Here is my take on this subject. Anybody that has changed disk brake pads, knows you use a "C" clamp or a suitable tool to force the caliber piston(s) back in as far as they go to allow for enough room for the new thicker pads to be installed And everybody that has done that also knows the extra fluid flows out the top of the master cylinder reservoir and if not caught, down on other items under the master cylinder and the ground. So the fact that your brake pedal returns via a spring system, allows a small amount of fluid to also return to the master cylinder and that small amount removes the brake pads just far enough away from the rotor to not ride on it. I can guarantee you that IF your disk pads are riding on the rotor, even a little, they will heat up enough to crystalize and become useless... JMHO!
 
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smokeonthewater

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The key is in your statement... ALLOWS fluid to return... Allowing fluid to return provides absolutely no retracting force.... It's the same as leaving a gate open... The open gate does not remove the cows from the field.... Another force would be required.... Likely the greener grass effect lol.
 

Thalasso

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As smoke said check the wheel brg. I am willing to bet it's not tight enough that it is allowing the rotor to spin out of true
 

Idlespeedonly

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If you have ever taken a master cylinder apart you would see the cup seals that are in most is designed to push fluid not suck fluid.
 

bruceb58

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You are using flex lines to the calipers right?

Fluid pressure has to be the same at both calipers unless there is a plugged line somewhere. Not sure what Dingbat was talking about.

Wouldn't surprise me if you had a sticky caliper from TieDown. The quality of TieDown products is questionable. I installed a set of TieDown brakes on my trailer and I threw them in the trash after I had a sticky caliper and other issues. I will never buy anything from TieDown again.
 
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21BaylinerCC

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Thanks for the feedback everyone. Looks like I'll be jacking up the trailer and checking the bearings, as a start.
 

21BaylinerCC

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Yes the kit came with flex hoses. I triple checked and there aren't any kinks in the lines. When bleeding, brake fluid flowed through both lines, so I do not think the lines are clogged.
 

bruceb58

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That's good. Some people connect hard lines to the calipers and wonder why the brake pads wear out on one side.
 

dingbat

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That's good. Some people connect hard lines to the calipers and wonder why the brake pads wear out on one side.

And why is this? "Fluid pressure has to be the same at both calipers unless there is a plugged line somewhere"?
 

bruceb58

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And why is this? "Fluid pressure has to be the same at both calipers unless there is a plugged line somewhere"?
If you have a hard line connected to the caliper, it keeps the caliper from floating on its pins. Has nothing to do with fluid pressure. The hard line ends up pushing the caliper against the rotor even when ther is no brake line pressure.

If your question was about pressure at the caliper, each caliper will have identical fluid pressure once the pads contact the rotor.
 
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