About 3500 miles ago, my left rear brake started making a clicking sound. It still works okay, but I think the piston is sticking a little bit. I can actually move the outside brake pad back and forth, which is causing the clicking sound. Its a rather metallic clanking, and goes away when I apply the brakes.

Anyone had this problem?

 

Is the retaining clip on the outside of the caliper?

 

Yes, it is still there.

 

Stock Parts?

 

No, it has Ferodo pads. But it started a few thousand miles after the pads were installed. I think its the piston.

 

Very doubtful it is the piston... why do you think so???

It is most like the pad trying to rotate forward or backward as you brake forward , then backward. It is not supposed to have any play but maybe your has just a tad of play. It will only take a few thousandths to make a noise.

Have you pulled the wheel and wedges a large screwdriver around to see if you can get the pads to move?

YD

 

There use to be a problem with pads with BMW's where they would do the same thing. You can try mushrooming the edges out to prevent the click from happening. That was an old solution. Also had the problem on another vehicle that I mushroomed the edges and no longer exhists.

 

Its not much play at all. I had them looked at today before my new rims were put on, and now its not clicking. Odd.

 

Clicking is not necessarily a bad thing. At least you know the pads are pulling away from the rotors. you can check out my new thread under Brakes/Wheels/Tires. I've gone thru three complete brake sets - rotors and pads - in 85K miles. Turns out my poor mpgs, poor acceleration, and extremely fast wearing rear brakes are the result of corroded or improperly working brakes.

The clicking sound has returned. Like the Song Birds of spring, this is a welcome sound.

 

Three sets in 85k? Yowza.

 

Installing brake pads is not just cram them in and go. Dealerships, independent shops and private owners can do it right and can do it wrong. You never know.

The metal backing plate of the pad is one of the places where one can mess up. This metal plate usually gets a nice thick coat of some sort of paint or coating at the factory. When you fit the pad into the caliper, this fit is one of the places you should pay attention to. If it is too tight, which is often is, you need to file or sand off just a bit of the paint on the ends so the pad fits into the caliper and will slide in and out (same motion as when the piston pushes the pad toward the rotor), without too much drag or also not too loose. If it is a very tight fit and left that way, the piston will push the pad into the rotor and when you take your foot off the brake pedal, the pad will want to stay there... causing premature pad wear.

If the pad is too loose, you get noises, like clicking. When you take your foot off the pedal, there is no spring or anything to pull the pad away from the rotor. It just sits there, very, very close to the rotor and ready to go at the first bit of brake pressure. This is why some brakes will screech a little when you are not touching the brakes. Also, if the pad is a little too loose, it can vibrate a little when you use the brakes lightly and cause a different noise. Some applications call for high temp grease on this sliding portion of the metal backing plate.

Some calibers are also sliding style. All calipers that have all the pistons on one side or applying to only one brake pad are sliding calipers. When installing new pads, one needs to take the sliding parts apart, clean and relube the sliding parts. If the caliper does not slide easily and properly, then the pad on the piston side will wear and the pad on the other side will not. Not only will you get uneven wear, you will get diminshed brake performance.

Not going into hard braking, race pads, slotted or drilled rotors, outgassing, anti-rattle springs, or clips or silicone sealeants or whatever here. Not going into high performance fluid or flexible hoses, either.

Just take your time and be willing to do a little custom fitting of each pad when replacing them and you'll be rewarded with very few problems.

Don't forget that brake fluid is hydroscopic... meaning it absorbs moisture. I have heard numbers of 2% per year? Water in your brake fluid does all sorts of bad things; causes rust and corrosion, rust and corrosion on your master cylinder bore and your caliper bores causes rough areas which chew up your rubber seals, which causes leaks. Moisture in the fluid lowers the boiling point, which causes a soft pedal, fading, etc. Bottom line, at a minimum, flush you brake fluid every other year. Your master cylinder and calipers will last longer.

Good luck and happy braking.

YD

 

Thanks for the advice! I actually have brand new blue brake fluid in the car now, so that shouldn't be a problem for awhile.

 

High performance fluid should be changed at least once a month, especially if you plan to track your car. Then, it should be changed before each even - a procedure I follow religiously.

Typically, the higher the heat resistence, the faster its propensity for water absorbtion.

Even with ATE or Motul, you will notice a distinct difference in pedal pressure required after about a month...and after a weekend at Watkins Glen.

Just thought I would add that for the folks planning on a track event or two...

 

No way can I afford to replace my ATE every month. The car has never been tracked, only Dragoned...

 

Edit>>> YD's post is right on the money.

I recently read that MINI's used in winter environments can have the e-brake cables hang. This can either cause a dragging brake or as in your case a loose pad. You might want to have a look see. Clean & lube the pivot points at the caliper cable connection. Also check the dust boots on the caliper pistons. If they're torn corrosion could be in there too. A bit of clean up should delete your problems.

You have a bit of a dilemma on your hands. ATE is a very good high performance brake fluid. Trouble is it is very good at absorbing moisture. That lowers the boiling point. Not a good thing. Stepping on the brakes only to find out you've boiled the fluid is an experience one never forgets. Can't compress the bubbles, YIKES no brakes. A quart of ATE is way cheaper than a new car, or a night in the hospital. Go maybe 3 months between deleting the old moisture laden fluid. Have fun be safe.

 

Check out my thread about poor mpgs under Drivetrain - it turned out to be the rear brakes...3 complete brake jobs in 85K miles. Mileage went from 23.1 to a high of 30.7 today and the car feels like it gained 50hp! All because those pins were not cleaned and lubed by BMW. They agreed to give us a credit for the total amount of the last brake job. Pads and rotors shot after 3,500 miles of driving.

I didn't have the tool for the rear brakes...now I do.

 

I don't think mine are dragging (well, there's the light, normal drag that you can feel when you spin the wheel freely). I get 22-26 mpg city, 30-38 highway. With mods!

 

I've been very good about cleaning & lubing the caliper slides on my Miata. Now I will start doing the same thing with my MINI. Thanks for the tip.

 

...meb pondered for a moment..."why, his conscious asked, are the rear wheels always so black?"