Hello, I tried to look threads for my issue, but couldn't find one so here I go. I have a MINI Cooper Justa 2010 Auto and for few months I have been hearing metal rubbing sounds from my rear right brake, getting louder every day. I checked the brake pad and it has a fair amount of pad left on it. I took it to the mechanic and they lifted it up and saw that the inner pad of the rear brake worn out completely and the metal's been rubbing the rotor, making the noise. Do any of you know of anything that the inner brake pad wearing out faster than the outer pad? Would this be the caliper issue?

Thanks in Advance for your help.

jh

 

Yes, it's a caliper issue. That inside piston is not retracting as it's designed to when pressure is taken off the brakes. You should have both rear calipers replaced or rebuilt and go through the pads and rotors to even them out as well.

 

funny thing 'bout that

right rear inner pad .... isn't that where the rear wear sensor sits????

brake sensors are right rear and left front and in both cases on the inner pad ....

or am I mistaken?

If not .... how did a right rear inner pad get to metal on metal with no indication? I smell a rat . . .

I took it to the mechanic

hmmmm .. what mechanic?

a 10'? You're out of maintenance coverage I presume? And the last time you took it in was?

of course this:

few months I have been hearing metal rubbing sounds from my rear right brake

does not bode well

 

Uneven wear is common on many cars...even non Mini's...
They can be lubed....or sometimes rebuilt/replaced. In either case a full brake job on that end of the Car is needed.
Sad you waited so long with such a dangerous situation.....gets more $$$ cause the rotor is now likely junk....lucky you did not wreck....

 

Capt_bj.
I think the sensor is on the outer pad, not inter pad. So I didn't get any warning light. Yet. I took it to my regular mechanic which does NOT specialize on MINI and I also took it to Mini special shop near me as well. My guy said to just replace the pads. The MINI specialist said to replace whole pads/rotors on rear. But I wan't to have second opinion on this as why the inner pad was worn out much faster. And the sounds started very small on seldom occasions few months ago and didn't bother to find out, but they started to bother me few weeks ago (I'm not too mechanical... )

jh

 

ZippyNH,
The MINI specialist told me that especially the inner pads wears quicker because the calipers are pushing them against the rotors. Is this true?

jh

 

As Capt_bj presumed, mine is 15k out of warranty and didn't try to contact any dealers.

 

Lol....pads only work when pushed against the rotor.....
The mini's brakes are pretty standard.... No specialists needed....just deal with somebody you trust that knows your goals/standards in mataining/fixing your car.
It is more important to get a set of pads on the car to be safe than get a million opinions....

 

No.
You need a new MINI specialist

If there is a significant delta in the wear of the pads, the caliper is sticking and needs to be rebuild. This is a fairly easy (if messy) DIY procedure, but if you are taking your car to a "guy" to do the pads, you probably should pay a pro do rebuild the calipers as well.

Measure the rotors to check if they need to be replaced as well.
Given that one side of the rotor is scarred from contact with the pad backing plate + the fact that plain rear rotors a cheap = I would replace them as well.

a

 

Thanks, all for your help.
My MINI has been fairly trouble-free for 3 year with 65K miles and this would be as big as it gets. I thought it would be great to start the journey of DIY (since the warranty is over), so bought the pads/rotors. But now it's way over my head - rebuilding the caliper and all (still tempting). I can't afford to do all those at the shop/dealer now - replacing pads/rotors/caliper at once (was quoted $500 for replacing pads/rotors) and I don't know how much it would cost for the caliper replacement. And while at it, they might suggest to do brake fluid flush as well... PAIN!!!!

jh

 

Rebuilt calipers vary in price.... And quality....rockauto has them cheap...but you must ship your old one back or pay a core fee....some folks do OK with rebuilds...some have had a couple fail...buyer be ware...if you swap the caliper out...a bleed is pretty easy if you temporarily plug the line to limit fluid leakage when doing the swap...

 

JH,
First of all - don't over-react.

"Caliper rebuild" sounds nefarious and complicated, but it is a VERY simple exercise of replacing a few rubber seals and the rubber dust boot around the caliper piston. Nothing fancy. I used to do it every winter during track off-season, along with bleeding the brakes.

Usually, the outside dust boot gets damaged from either road debris or heat, and the dirt causes the piston caliper to not retract fully. You pinch the brake hose, push the caliper out all the way, replace the seals, push it back, bleed the brakes to get any air out. Drink 1/2 beer. Repeat on 3 other corners, or stop right then and there.

Seals cost maybe ~$5 per corner (should be more like $0.50, but nothing costs less than a few bucks), a quart of decent brake fluid ~$15, a brake bleeder ~$50.

Figure about 1 hour of labor, including jacking up the car, take the wheel off, taking the caliper off (pads pop out for free). Add another 5 minutes to replace the rotor if necessary. 3x the time if it's your first time at the rodeo.

If you are near NYC, drop me a line and we can do it in my garage.
You are buying the parts and the beers.

alex

 

There is absolutely NO REASON to ship anything anywhere.
This is a simple DIY job.

Here is a link of someone doing it on gen1 mini brakes with ample pics:
https://www.northamericanmotoring.co...beginners.html

Here are a few links to DIY caliper rebuilds on MINIs and BMWs (same hardware):
http://www.pelicanparts.com/bmw/tech...ad.php?t=39965
Rebuild/101-Projects-52-Caliper-Rebuild.htm

FYI - instead of removing the caliper line and using compressed air to push out the piston, you can carefully push it out with the brake fluid via the brake pedal. Just make sure to (a). arrest the caliper progress with a piece of wood/plastic, else it may shoot out and get scratched; (b). brake reservoir stays full of brake fluid so that air is not introduced into the brake lines (power bleeder kit is great for this); (c). Stop pushing on the brake pedal as soon as the caliper is out to prevent excessive brake fluid loss (have a helper on duty to tell you when the caliper and seals are out, and block the brake line to stop the fluid flow.

HTH,
a

P.S.: Here is one brake bleeding kit, similar to the one I have: http://www.turnermotorsport.com/p-28...pean-cars.aspx

 

Kink the brake line?


No thank you. You risk an internal tear..

Just use a stock bolt and the old crush washers to block the fitting at the caliper off.

This is REAR calipers.. Don't bother to rebuild them... Ever... This is not the same job as the fronts.. Integrated parking brake systems are a total PITA to work with. I 2nd the Rock Auto route.

This is not a R50/53 rear caliper, its an R56 design... the parking brake is integrated.. the issue is the piston gets seized... this almost happens on every rear brake setup... with an.. Automatic... people never set the brake.. it causes the rear brake to never self adjust (see why you never rebuild them?).. the internals, the ramps, *****, they all rust... its makes it impossible to retract.. even with the tool...

 

Thanks, Alex, for your info and offer. I am in SoCal. If you come down, definitely beers on me.
Dan, it IS the rear caliper. :(

jh

 

I've done many a set of MINI pads and rotors and the question was rhetorical - the sensor IS on the inner pad . . .

If you've done nothing yet ... what's the thickness of the pads, inner and outer?

The MINI specialist told me that especially the inner pads wears quicker because the calipers are pushing them against the rotors. Is this true?

it is BS ... how does the outer pad come into play??? The whole point of the system is that when the piston presses, the pads get pushed together and squeeze the rotor. Yes higher end calibers have pistons on both side, but the OE calibers 'float' and if they float correctly the squeeze should be even. It appears yours do NOT float correctly. That does not mean the caliber is bad - the piston is probably moving correctly, but the entire caliber is not 'floating' as it should. Disk pistons don't retract, they just stop squeezing and lack of pressure on the pads means all they do with their minimal drag is keep the rust off the rotors.

The MINI specialist said to replace whole pads/rotors on rear

see many threads on this - the original MINI service policy was to ALWAYS replace rotors when they replaced pads . . . they have since dropped this.

If I had this problem the first thing I would do would be inspect the caliber pins and lube them .... heck I'd replace them and the bushings. They are inexpensive parts. This is a normal part of a pad and rotor change when I do 'em - inspect and lube.

Don't take this personal but this:

I checked the brake pad and it has a fair amount of pad left on it. I took it to the mechanic and they lifted it up and saw that the inner pad of the rear brake worn out completely and the metal's been rubbing the rotor,

tells me you don't know what you're looking at ....

here's a new pad with some white paint on the backing plate



and here's a pad at the end of its life - when the pad material is thinner then the backing plate


bring your car and parts over and I'll hang 'em for free and we'll replace the sliders and see if the problem goes away .... or if you even ever had A problem beyond excessive wear ....

the bottom line - you have yet to find a decent brake guy .... I'd not return to either of these places ....

finding a good mechanic is as important as finding a good dentist .... you would like them to do a good job but not feel like they ripped your big toe off thru your mouth.

 

Well said capt BJ!!
+1 to all the above...
The basic home rebuilt is to just stop leaks....a reman unit has more done... And the rears DO have extra mechanisms due to the parking brake... So it is not as simple as described.

 

^ This x1000 for the win.

That is why they wear more on the inside then the outside. The pins garf up. This is an issue with all floating caliper designs.

oh.. and its caliPer... not caliBer.

 

I think Danjreed may be on to something. The caliper pins my be the culprit. Let's see if I can explain this clearly. This is a "floating" type caliper. The caliper has mounts for both inner and outer disc pads and has the piston mechanism. The outer pads is the stationary (fixed) pad and the inner pad is the sliding pad that the caliper piston pushes on. As you apply pressure on the brakes the piston applies pressure on the inner pad causing it to slide in the caliper mount closing the distance between the inner and outer pads. This movement squeezes the rotor between both pads thereby stopping the rotor from spinning. To allow the caliper to move freely and keep the disc pads centered on the rotor, it is mountered on two pins. The whole caliper mechanism slides in and out on these pins. If these pins get all "junked" up, rusted, damaged, etc. then the caliper would be unable to slide freely and keep the pads centered to the rotor. If this is the case then it is possible that the inner pads are "riding" tighter against the rotor causing more wear.
I'm not an expert but this sounds feesible....

 

think of your basic C-clamp. Only one side adjusts ... but the clamp applies pressure evenly on both sides does it not? Well, it does so long as nothing keeps the C part from moving (assuming that the clamped part can't move as is the case with the rotor)

If your slider pins are binding the C isn't moving and that can cause pressure on just the adjustable side which is BAD.

from Wiki:

A floating caliper (also called a "sliding caliper") moves with respect to the disc, along a line parallel to the axis of rotation of the disc; a piston on one side of the disc pushes the inner brake pad until it makes contact with the braking surface, then pulls the caliper body with the outer brake pad so pressure is applied to both sides of the disc. Floating caliper (single piston) designs are subject to sticking failure, caused by dirt or corrosion entering at least one mounting mechanism and stopping its normal movement. This can lead to the caliper's pad's rubbing on the disc when the brake is not engaged or engaging it at an angle. Sticking can result from infrequent vehicle use, failure of a seal or rubber protection boot allowing debris entry, dry-out of the grease in the mounting mechanism and subsequent moisture incursion leading to corrosion, or some combination of these factors. Consequences may include reduced fuel efficiency, extreme heating of the disc or excessive wear on the affected pad.

{emphasis added}

 

Thanks so much, guys. That clears up some confusion I had. I didn't look and inspect the pads myself, but that was what I was told from the mechanics. I am on vacation for few weeks from tomorrow, but after I come back, I will jack it up and inspect them myself. Thankfully my first journey of DIY would be much smoother with all your help.


jh

 

jamadeus- please keep us posted on your return!

 

You are right -bad choice of words on my part.
Don't kick - block the line.

If the brake lines comes off: a golf tee and some kitchen shrink wrap usually do the trick.
If you don't disconnect the caliper from the brake line, then keeping it elevated + the vacuum from putting shrink wrap under the brake reservoir cover worked for me.


As long as you can get the caliper out with either brake fluid or air pressure, there is nothing to be afraid of about R56 rear calipers. Inserting them back will require some pressure + turning, but that's a given for any rear brake job.

PepBoys can loan-out rear caliper tool for free.
You can buy your own set from many sources, including the following: http://www.northerntool.com/shop/too...FUyi4AodZ0YANw

a

 

+1 on the caliper pin idea.
I never had this happen on any of my cars, but it sounds promising and simpler than caliper rebuild.

Either way: take the caliper off, inspect the pins and the rubber boot, and proceed from there.

a

 

You dont even have to pull the caliper... Just the pins.

Make sure you lube them with the right stuff..

Don't use a grease/petroleum based lubricant.