Dragging front brake or stuck caliper

[rverdoold]

I have a 1999 impreza wagon 1.6 5MT (front disc rear drum, no ABS) and have the idea one of the brakes are not working as they are designed to do. They stop the car so they do work. However during my last trip throughout europe I had a couple of times the idea i was smelling 'clutch' but it could not have been because it usually happened after driving for some time and then stopping. So I would go for smelling brake.

 

So what did i find out:

 

• the front left rim is much more dirty than the right one (in the sense of brake dust) I mean left is nearly black while right is almost clean.
  
• The smell was coming from the left wheel side.
  
• After stopping the disc heat dispersion on the left felt warmer then on the right (i did not touch the disc to see what degree of burn wound i would get)
  
• I have to get the brake pads out but it seemed that left was worn more than right.
  
• oil in the reservoir is above half way between min / max
  
• Brake booster works (there is vacuum)
  
• on sand can lock up bot front wheels (i think, it did not drag the car to one direction)
  
• While normal braking to a stop the car is not really dragged/pulled to a direction
  

 

Any ideas what this could be

Could be that the left brake caliper is not retracting enough so the pad stays in contact with the disc and what could cause this?

 

EDIT:

As far is i know i do not have a hill-holder (at least then i never got it working)

Edited June 28, 2010 by rverdoold

[sparky11]

When was the last time you serviced / cleaned / lubed the brakes? The pads could be sticking in their slides and dragging slightly on the rotor. A flex line starting to go bad could also be the cause. A sticking caliper is usually from lack of lube on the slide pins. Of course only lube the caliper slide pins and the pad ends. This should be done annually. Rear shoes should be service in the same manner annually also.

 

Changing the brake fluid every 2 years or 30,000 miles will keep the master cylinder, calipers and wheel cylinders working for the life of the car. Never retracting the caliper or wheel cylinders without opening the bleeders will keep from backing dirty fluid and particles into the master cylinder and causing a failure there.

[rverdoold]

I bought the car at 59k KM and it is at 85k now. Going to do major service at 88k.

I guess it still has its first brake oil in there and first pads as well. Think will take the pads out and regrease the backside with copper grease.

 

Last time i changed brake pads on my previous sub i slowly pushed the piston/cylinder back with the cap from the reservoir. I guess that was the quick and dirty way and incorrect?

 

Flexlines are easy to replace at least they look like that. Is it worth installing speedbleeders?

[sparky11]

Service the brakes first - easiest and cheapest place to start. Only replace parts if servicing fails to correct any sticking or noise issues.

 

Soak bleeder with a rust penetrant first the day before if you think they are going to be a problem. Open bleed screw a few turns to make sure it turns freely and to make sure it is clear and close it back up lightly. Remove lower caliper slide / bolt and pivot it up. Use a big pair of channel lock pliers to retract the piston after you reopen the bleed screw -- I use a hose and container to catch the old fluid. Slide the caliper off the upper slide pin and hang of the side with a wire or set it on the suspension. Pry the pads out of their slides and remove the stainless steel slide insert. Clean the pad slide hardware and the hardware mount areas in the caliper frame using a wire brush and a flat blade screwdriver if needed. Clean the pad ears that ride in the caliper frame.

 

Clean buildup from inside the caliper, around the piston / boot area and outer pad contact areas, being careful not to damage the piston boot(s). Clean and re-lube the slide pins. Add a little lube into the slide pin boot. USE LUBRICANT APPROVED FOR THIS OR THE BOOTS WILL BE DAMAGED!! I spray every thing down with brake cleaner after I'm done scraping and brushing.

 

If re-using the pads, I always lightly sand them to break their glaze and spray with brake cleaner. Dry fit the pads back in the caliper frame with the hardware reinstalled to make sure they ride freely -- if everything is good lightly lube the pad ends and install them in the caliper frame. If the pads are stiff or stick in the frame sand/grind the ears and ends until they move smoothly. Make sure that the noise reduction shims are in place --hopefully you removed and cleaned them as well. Lubricate the piston and outer pad contact areas of the caliper and reinstall. Repeat for the other side.

 

If you are using new pads, remove and turn the rotors or replace them. Dry fit the pads in the caliper frames to make sure they slide freely. I have had to grind the ears on some aftermarket pads because they fit so tight they would stick against the rotor.

 

Rear drums -- remove the drums and clean out all brake dust from the drum and from the brake assembly /backing plate. Make sure the adjuster turns freely. Spray a little rust penetrant on the threads to free up and lube it. De-glaze the shoes and spray with brake cleaner. Pry shoes from backing plate and lube the shoe / plate contact areas. I always remove the rust lip on the drum and buff the inner and outer hub mounting areas and never- seize / lube the central hub mount lip. Check shoe adjustment and parking brake adjustment.

 

Lastly bleed / flush completely all the old fluid out of the system until you get clear fluid from each wheel.

 

Brakes service is not hard but as they say "God is in the details!!"

[sparky11]

I have never used speed bleeders, I either have someone pump the pedal for me or I use a Mighty Vac brake bleeder system.

[rverdoold]

So took of the wheel today and was not able to easily turn a bit. I could hear the disc scraping the pads. So for sake of testing tested the other side as well. And there was without scraping. So moved over to the left side again.

Removed the calliper bolt and removed the first pad. That was worn but still 2 mm left or so. But the inside pad could hardly be removed it was very stuck in the anti rattle clip.

Managed to get it out and it was worn but not evenly. The stuck side at least 1 mm more than the other. The grinder pin was almost touching the disc as well so ready for replacement. Took out the clip and bended it a bit so pad would fit normally again. Than had to depress the calliper to get it back on. But to do that i unscrewed the canister but the freaking cap fell of and slide down on top of my underbody protector . So had to screw that one off as well NOOOOO. Ok got it back got the calliper back and put everything together. Of course i undertorqued the calliper holder bolt by 17 Nm (figured that out after driving 30 miles) (got lost in US to Metric conversion). So for the fun can take the wheel off again and uptorque it. Feels like a very bad day. Left the underbody plate off since will change all oils next week for maintenance. Now will have to change pads as well.

 

Question:

Can brake drag be caused by the pad stuck in anti-rattle clip?

[idosubaru]

yes, i've seen it before. so far it has been due to corossion or build up - basically the clip is dirty and damaged. it needs cleaned or get new ones so the pad can travel over the service otherwise it can hang. i actually like buying the NAPA Adaptive One pads...though i'm sure there's plenty others...because they come complete with new clips/etc. they should be available at parts stores too, or clean yours. since all of my cars have age i consider greasing the slides and cleaning/replacing those clips as part of a brake job.

[rverdoold]

At the moment at 96k and had to make emergency stop in order to not damage my hood with a cyclist (his fault but still do not want to hit him). There is no abs so wheels locked, ok.

When i drove away it felt a bit heavier, driving at highway speeds of 60 mp/h the steering started to shake (never had that before) and i stopped on the shoulder. Left fron wheel was boiling hot even some light smoke came off. Front right and back were fine. Lifted the car with the jack and turned the wheel for and backward. I could see the outer pad being free now. Drove 30 miles home without a problem. However at home the left front wheel was still significantly warmer than the right (spraying water on right left a film of water, on the left it evaporated off with some sizzing).

I think the caliper might be stuck a little bit and going to take it off tomorrow.

Anything I should look at?

Normally I remove the lower bolt and fold the caliper up to check the brake pads. (now the brake pads can move freely in the holder, I removed a bit from the ears 5K ago)

What will happen when i press the brake a little little bit when not mounted. I suppose the caliper comes out somewhat further. This will allow me to clean the caliper shaft and grease it with copperstuff.

Secondly could old brake oil cause these probles with only 1 wheel. Can I test the oil. Since I have no idea how to replace it.

 

Earlier it was said a worn flexhose could be causing sticking brakes. How can this happen I can not really visualize/understand how? Can you help me!?

[rverdoold]

Think it might be wise to change the oil and both flex hoses in the front. However those things go not for under 50 euros per piece ($70), WHY? in US the cost only 30 dollars.

For brake fluid which one to use Dot 3, 4 or 5. and how to proceed. And how much goes in the brake system, it does not look a lot to me I think.

Just open one bleeder and keep adding new till it is clean what runs out. Then Proceed with the others.

 

Secondly, if the cap on the master cylinder is closed will the system drain when I remove a flex hose?

[ajhswan]

Fixed Subaru dragging brake Calliper

 

I had a similar issue to this and have come up with a solution I have not found mentioned elsewhere; Thought I would share, as it would have saved me a lot of time, pain and money had it been out there before;

 

The cause of the drag turned out to be over-lubrication of the calliper slide pin that has the anti-rattle rubber on it. The drag was so severe that I had smoke coming out of one front wheel from the burning hot rotor, which got so hot I seared 3 fingers touching it momentarily.

 

I had noticed, when I was rebuilding the calliper, that the slide pins were pretty dry so I added lube and a bit of silicone spray. This made them move very nicely, but I realised later that it allowed the one with the rubber on the shaft  to seal so it had trapped air below the pin that tends to force the pin back out of the hole.

 

The effect is that it puts a lot of pressure on the outer disk pad as it is forcing the mobile part of the calliper mounting away from the pin towards the centre of the car.

 

The solution is to clean all the lubricant, gunk etc out of the hole in the calliper then place a minimal amount of brake lube grease on the shaft. Check the anti-rattle rubber to make sure it has not swollen as this will cause the problem as it will seal in the bore of the calliper slide; You may need to get a new rubber if this has happened;

 

The rubber I had had 2 flat sections to allow air movement, but these were not evident on the old one, but I suspect that was swell from the grease and maybe the silicone.

 

I will be monitoring and may need to groove the shaft or the rubber to ensure it does not jam up.

[1 Lucky Texan]

some folks just remove and toss that sleeve away - some popular lubes are incompatible with that rubber and cause it to swell.

[idosubaru]

The cause of the drag turned out to be over-lubrication.....so I added lube......then place a minimal amount of brake lube grease.........was swell from the grease and maybe the silicone.

this misses the prevailing issue(s). 

 

1. it's not "grease" and "lube" in the generic sense, that misses the issue entirely.  the issue is the *type* of grease, not amount or process.   old types of caliper grease will cause the rubber pin bushings to swell and seize in the caliper bore.

 

2.  Subaru's OEM grease is excellent or Sil Glyde or other high quality grease that won't impact the bushings. I haen't researched it but i presume it just needs to be silicone based?  I use it in all my Subarus even those without rubber bushings because it lasts so much longer.

 

3.  Or you can throw the pin bushings away and use whatever grease you want.  They're pointless and unnecessary, i've been doing it for years. 

 

I do both, throw away the bushings and use better grease.

 

4. If you regrease the slide pins every tire rotation or two your brakes will last the life of the vehicle on basic pad and fluid changes.  you'll never need to replace rotors or calipers or have slide pin issues. 

 

i usually also replace the caliper pad clips after 150-200k miles as they can get bent or built up or corroded over time and hang a pad, though they can be easily inspected to check for any build up or deformity that could cause issues.